Evaluating Potentially Toxic Elements Under Prolonged Application of Pig Manure in Brazilian Soils

Evaluating Potentially Toxic Elements Under Prolonged Application of Pig Manure in Brazilian Soils | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluating Potentially Toxic Elements Under Prolonged Application of Pig Manure in Brazilian Soils Ana Paula Lemos, Diego Antonio França Freitas, Adebayo Jonathan Adeyemo, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6019209/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Pig manure (PM) is crucial for animal protein production, especially in Brazil, where pork is widely consumed. However, managing animal waste remains a challenge. While PM serves as a soil amendment, it may also introduce potentially toxic elements (PTEs), such as heavy metals, into agricultural soils. Few studies address the impact of long-term PM application on the availability of these metals at various soil depths. This study analysed copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), cadmium (Cd), and lead (Pb) in soils with prolonged PM use in Florestal (FL), Pará de Minas (PDM), and São José da Varginha (SJV), Brazil. Samples were collected from six soil depths using the Mehlich-1 method, with element concentrations determined via atomic absorption spectrophotometry. Data were analysed using ANOVA and Duncan’s test (5% probability). The results showed that soils with PM had higher levels of Cu and Zn, with Cd elevated only in PDM. Fe and Mn showed no significant differences, whilst Pb was higher in FL and PDM soils without PM. PM application increased Cu and Zn levels but did not significantly affect the other elements. In conclusion, long-term PM use elevates Cu and Zn levels in soils, posing potential risks of Zn toxicity. Public policies are needed to regulate PM usage, reduce soil pollution, and promote sustainable waste management for environmental health. Pig manure toxic metals PTEs Brazilian soils Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1 Introduction Pig production is a significant global provider of animal protein for human consumption [ 1 ]. Although pork is the most consumed meat globally, it ranks third in Brazil after poultry and beef [ 2 ]. In early 2024, worldwide pig production was 114.15 million tons, surpassing poultry and beef production at 103.26 million and 59.48 million tons, respectively. Pork plays a significant role as a meat in Brazil, with 18 kg consumed per person in 2023. Brazil is likewise one of the largest pig-producing countries in the world, with 46.5 million animals in a herd, and production is projected to increase even more. Although there have been achievements, pig production is associated with massive environmental issues, specifically animal waste disposal, which is of extremely high risk in terms of pollution according to volume and chemical complexity [ 3 ]. While to some, pig manure (PM) is an organic waste, other scholars consider PM as an essential resource in improving soil quality and plant productivity [ 4 ]. Its high nutritional content includes macronutrients such as nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) and essential micronutrients such as copper (Cu) and zinc (Zn), which are helpful during crop production [ 5 ]. Managed PM application can also increase soil physical parameters, promoting improved infiltration rate, lowering bulk density, erosion, and rising availability of soil moisture, P, and K, favouring crop growth [ 6 , 7 , 8 ]. Brazilian reports establish the agronomic value of PM-based fertilizers [ 9 , 10 ]. Despite its virtues, PM manufacturing surpasses soil absorption capacity for nutrients in compact farms, hence presenting the excess disposal issue [ 11 ]. Unregulated application of PM risks the environment with the build-up of nutrients in the topsoil layer, mainly phosphorus, which has the potential to contaminate water bodies [ 11 , 12 ]. Furthermore, animal waste can harbour unwanted contaminants such as antibiotics, pathogens, and potentially toxic elements (PTEs) like heavy metals Cu, Zn, Fe, Mn, Co, and Cd [ 13 , 14 ]. These elements harm the environment due to their toxicity and bioaccumulation tendency, which causes adversity to human health [ 15 ]. Animal manure has been recognized as a significant source of PTEs in agricultural soils [ 16 ]. Tiecher et al. [ 17 ] found substantial Cu and Zn enrichment in surface soils after long-term PM application in Brazilian agrarian fields. Smanhotto et al. [ 18 ] also reported Cu and Zn accumulation after annual PM disposal for 4–22 years in western Santa Catarina. Matos et al. [ 19 ] analyzed Brazilian soils in Barcarena and found Cu, Ni, Zn, and Hg at high concentrations above national safety levels. Most studies have examined the essential micronutrients and overlooked the availability and level of contamination of non-essential metals like Cd and Pb. Few studies have determined soil under realistic field conditions or sampled soil up to a depth of one meter. This study bridges these gaps by evaluating the long-term PM application effect on bioavailable PTE concentrations in soils from three sites in Minas Gerais State, Brazil. Findings provide the path for local farmers to adopt sustainable PM utilization to minimize toxic element release and soil pollution. Data collected on PTE fate in PM-amended soils in target regions of Minas Gerais will inform better waste management practices. This research will enhance knowledge of metal behaviour in treated soils, enabling sustainable production to minimize environmental pollution and enhance human health in the region. 2.0 Materials and Methods 2.1 A brief description of the study area The present study was carried out at three different places, namely Florestal, Pará de Minas, and São José da Varginha, in Minas Gerais (MG) State of Brazil. Geographically, the district is situated between Latitude 19°52'42.81" S, Longitude 44°24'46.79" W; Latitude 19°47'34.27" S, Longitude 44°37'32.35" W; and Latitude 19°44'59.57" S, Longitude 44°32'29.94" W, respectively (Fig. 2 ). Altitudes in MG vary between 76 and 2892 m, with topography favourable for mesoscale circulations, which develop due to valley and mountain breezes [ 20 ]. Topography, land use, and land cover also play a crucial role in the climate of MG because it determines the region's microclimates. This was done within the state where the selected sites present a high production of pigs and presently occupy the third position as the largest based on pig production [ 21 ]. According to Reboita et al. [ 22 ], the climatic condition of the study areas corresponds to a tropical savanna region, with a marked dry spell throughout winter. The average annual temperature varies from 19.5 to 20.7°C, while the average annual rainfall ranges from 1306 to 1419 mm yearly [ 23 ]. The textural type of soil is presented in Table 1 . Table 1 Soil physicochemical characteristics (0–10) cm of the two sampling sites in each location Parameters Locations FL PDM SJV PMS NPM PMS NPM PMS NPM Soil Classification (BSSC) Red-yellow dystrophic latosol Dystrophic haplic cambisol Red dystrophic latosol Sand (%) 40.43 42.27 41.95 38.72 37.67 38.37 Silt (%) 25.30 23.77 27.37 32.89 11.05 14.11 Clay (%) 34.27 33.96 30.69 28.39 51.28 47.52 BD (gcm -3 ) 1.12 0.95 1.23 0.88 1.03 1.05 pH in water 5.67 5.05 5.30 4.98 5.55 4.32 TOC (mg C ha -1 ) 4.23 4.24 2.42 3.22 4.29 3.91 Avail. P ( mgdm -3 ) 39.12 13.78 1321.89 10.95 497.16 5.78 Exch. K (mgdm -3 ) 87.20 239.77 521.70 168.29 178.30 79.56 Exch. Na (mgdm -3 ) 19.44 15.25 61.45 7.32 14.50 8.53 Exch. Ca cmol c dm -3 ) 4.34 1.71 3.55 1.54 5.80 0.22 Exch. Mg (cmol c dm -3 ) 1.65 1.41 0.90 1.05 2.24 0.09 Exch. Al (cmol c dm -3 ) 0.26 0.66 0.20 0.57 0.04 1.69 TEB (cmol c dm -3 ) 6.21 3.73 5.68 2.93 8.00 0.21 H + Al (cmol c dm -3 ) 5.61 8.09 5.42 7.78 6.81 8.67 t (cmol c dm -3 ) 6.27 4.27 5.83 3.44 8.03 1.57 T (cmol c dm -3 ) 11.82 11.83 11.10 10.71 14.81 5.64 m (%) 1.14 16.73 3.14 17.66 0.23 86.74 V (%) 51.78 30.74 49.71 27.11 52.73 3.68 BSSC: Brazilian System of Soil Classification; BD: Bulk density; TOC: Total organic carbon; TEB: Total exchangeable bases; t: effective cation exchange capacity (ECEC); T: cation exchangeable capacity at pH 7.0 (CEC pH 7.0 ); V: Base saturation; m: % aluminium saturation; H + Al: Total acidity. PMS: poultry manure site; NPM: non-pig manure. Florestal and São José da Varginha (SJV) are located in the central metropolitan region of Belo Horizonte, while Para de Minas is in the central-western region of MG. A flat or gently undulating relief characterises the topography, while the Atlantic Forest and the Cerrado are the two biomes that cover these areas. However, the study is located within the limits of the Cerrado biome, with fragments of semideciduous seasonal forest occurrence[ 24 ]. Florestal soil is classified as Red-yellow Dystrophic latosol [ 25 ]. São José da Varginha (SJV) is a Cerrado biome, dominated by vegetation characteristic fragments of the ecotone, with species of semideciduous seasonal forest and Cerrado Sensu Stricto [ 24 ]. The soil is dominated by low-activity clay called Dystrophic Haplic Cambisol [ 25 ]. Physiogeographically, Pará de Minas is located in the Atlantic Forest Biome [ 24 ]. However, it is amid a phytogeographic transition with the Cerrado, with some areas predominating mountainous vegetation and others with semi-deciduous seasonal forest. The topography is also marked by a flat, gently undulating relief with Red Dystrophic Latosol. It is one of the cities that make up the Belo Horizonte Metropolitan Necklace. Its proximity to the capital and federal highways gives the city a strategic location for the flow of agricultural, livestock, and industrial products and easy access to important regions of the country, such as the Minas Triangle, São Paulo, and Vitória. This location favours the city's economic development, represented by a diversified economic base emphasising industrial activities and agribusiness. Cattle, poultry, and pig rearing are the most representative livestock activities in the three selected locations of the study areas. Of these, poultry and pig rearing are dominant [ 21 ], and all of these serve as their primary source of income. In the PDM area, pig manure application has evolved over 20 years, starting with surface applications from 1998 to 2008, transitioning to maize with surface-irrigated slurry, and then corn and beans from 2008 to 2019 using a hydro-roll irrigation system. Since 2019, corn has been planted annually with no crop rotations. Initially, pig manure in slurry was distributed via gravity and contour-based methods over 15 hectares at a rate of 7 litres/m 2 /week. Recently, only potassium was added to the manured fields. In SJV, slurry application methods vary between sprinklers and robust hoses over 6.5 hectares without specified dosage control. Previously used for pasture, these fields now support corn crops for three years, receiving a single chemical fertilizer application of 244 kg/ha NPK 6-30-10 the year before the study, with no liming reported. Post-harvest, fields remain fallow until the next planting season. The farming activities of the local people include conventional cropping, dominated by cassava ( Manihot esculenta ) and maize ( Zea mays ), soybean ( Glycine max (L.) Merrill), cotton ( Gossypium herbaceum ), eucalyptus ( Eucalyptus globulus ), sugarcane ( Saccharum officinarum ), coffee ( Coffea arabica ), bean (Phaseolus vulgaris L.), and potato (Solanum tuberosum), scattered tree crops like orange ( Citrus sinensis ); these activities took place both in rainy and dry seasons as per the historical findings from the dwellers. The local conditions of the soil present medium vulnerability to environmental contamination by land use. According to Soares (2024), one should take care regarding the use, management, and conservation of the soil, including possible risks of contamination by PTEs. 2.2 Soil sampling and collection: The study employed a chronosequence approach, specifically, two sites were identified in three different locations, with each location being two kilometres apart. These were an alternative agricultural land with a prolonged application of pig manure and a nearby site of native vegetation used as a reference. A chronosequence approach was used in this study since there was no long-term experiment on the set-up presented in this research. This approach is based on the supposition that space can substitute for time [ 26 ]. Soil chronosequences reveal how time influences soil formation and its interactions with climate, vegetation, microorganisms, and land use changes, enhancing understanding of soil development processes [ 26 , 27 ]. The sampling scheme of a 3 x 3 grid, consisting of 9 points 50 meters apart, was used on a sample coverage of 1 hectare of land on each site (Fig. 1 ). Six soil samples were collected along a 100-centimetre depth at each point, separated into sampling layers of 0–10, 10–20, 20–30, 30–50, 50–70, and 70–100 cm. A 130 x 130 x 130 (cm 3 ) trench was opened at the centre to collect undisturbed and disturbed soil samples (P5). The soil was collected manually to a depth of 100 cm. At each of the four extreme points of the sampling grid (P1, P3, P7, and P9), a 40 x 40 x 40 (cm 3 ) trench was dug, and soil samples were manually collected between 0–10, 10–20, and 20–30 cm layers. A Dutch auger collected soil samples between 30–50, 50–70, and 70–100 cm soil layers to avoid contamination. At the other points of the sampling grid (P2, P4, P6, and P8), collections were performed between 0–10, 10–20, 20–30, 30–50, 50–70, and 70–100 cm layers, using an auger. Composite samples were then taken from six distinctive layers, and these were repeated in all nine sampling points, in two sites and the three locations. The experiment units that contain three hundred and twenty-four (324) were later combined to make one hundred and eight (108) treatment combinations, arranged in 6 × 2 × 3, respectively representing the depths, sites, and locations, replicated nine times initially and later bulk to three. One part of the soil sample was packed in clean and sterilized polythene bags; later, the samples were sieved through 2 mm for the selected chemical analysis. All samples were immediately stored in well-labelled sealed plastic bags in a cooler and transported to the management of Soil and Water Conservation Laboratory, institute of Agrarian Science of Florestal campus, the Federal University of Vicosa, state of Minas Gerais- for the chemical determination within 3 days of sampling. 2.3 Laboratory analyses Soil samples were analyzed for pH using a 1 to 2.5 soil-to-water ratio. Potential acidity (H + Al) was assessed using McLean's [ 28 ] SMP single-buffer method, while available phosphorus was determined through the Mehlich-1 solution method [ 29 ]. Exchangeable potassium (K) and sodium (Na) were extracted similarly, with K and Na quantified by flame emission photometry [ 30 ]. Total organic carbon was measured by wet oxidation, involving 0.5 g of soil treated with potassium dichromate and sulfuric acid, heated at 170°C for 30 minutes, and titrated using ferrous ammonium sulfate with Ferroin indicator [ 31 ]. Calcium (Ca) and Mg were extracted using a 1 mol/L KCl solution, and their concentrations were determined by atomic absorption spectrometry [ 32 ]. Total N content was analyzed via Kjeldahl digestion [ 33 ], and CEC was measured using the ammonium acetate method [ 34 ]. Exchangeable Al was assessed using 1 mol/L KCl and titrated with 0.025 mol/L NaOH until the solution changed from yellow to blue [ 35 ]. Additional soil parameters such as the sum of total exchangeable bases, effective cation exchange capacity, cation exchange capacity at pH 7.0, base saturation, and Al saturation were calculated following Ribeiro et al. [ 36 ]. Bulk density was determined using the volumetric ring method, where a known volume ring is filled with soil and weighed, allowing density calculation by dividing the soil mass by the ring volume [ 37 ]. Drying soil samples quantified soil moisture at 100–105°C for 24 hours [ 38 ]. 2.4 Analysis of the micronutrients Replicates soil samples collected from each depth and the three locations were air-dried, crushed in a porcelain mortar, and then sieved through a < 2 mm mesh stainless sieve. The potential toxic elements of interest (Cu, Zn, Fe, Mn, Cd, and Pb). The metals were determined using the Mehlich-1 extraction method to separate the metals present in the soil. This technique is widely used in soil analysis when a chemical evaluation of the amount of metals available for plant absorption is desired [ 39 ]. The use of the Mehlich-1 solution for the extraction of available metals in the soil is due to its simplicity of preparation and the fact that it presents a strong correlation between the content of metals absorbed by plants and the content available in the soil[ 40 ]. This method involves extracting elements from the soil using a solution containing 0.05 mol L − 1 diluted hydrochloric acid (HCl) and 0.0125 mol L − 1 hydrogen tetraoxosulphate (vi) acid (H 2 SO 4 ) in a soil: extractor ratio of 1:5. The methodology used to extract the elements were adapted from Embrapa´s Manual of Chemical Analysis of Soils, Plants and Fertilizers [ 41 ]. The reading was determined by an AA 7000 atomic absorption spectrophotometer, Shimadzu, with air/acetylene flame, installed at the Multiuser Center of the Federal University of Viçosa, Florestal Campus, Minas Gerais, Brazil. Quality assurance of the atomic absorption spectrophotometry (AAS) analysis was maintained by calibrating the spectrophotometer with certified standard solutions before each analytical batch. Additionally, blank samples and reference standards were regularly analyzed during each set of measurements to confirm instrument accuracy, sensitivity, and reproducibility. Each soil sample was analyzed in replicates to ensure the precision and reliability of the results. 2.5 Statistical analysis : Data obtained were analyzed using variance analysis with the general linear model of Minitab 17.0 edition. Collected data were analyzed to test for the main and interaction effects of prolonged sites amended with pig manure under different depths and locations on measured and selected soil parameters. Tukey HSD test was the statistical post-hoc applied to check for significant differences among means obtained at a 5% probability level of confidence. The results were presented in tables and graphs. Microsoft Excel 2007 calculates treatments´ means and standard errors before plotting the graphs. 3.0 Results 3.1 Initial soil physicochemical properties of the study area The study analyzes soil properties across three Brazilian sites (FL, PDM, SJV), comparing manure-treated areas with adjacent non-manure soils, is presented in Table 1 . It was revealed that manure application slightly reduces sand content while increasing silt and clay, suggesting that manure impacts soil texture by enhancing finer soil fractions. Manure generally lowers soil bulk density and increases soil acidity in untreated soils. Total organic carbon levels varied, with higher TOC in manured soils at FL and SJV but lower at PDM, possibly due to differences in manure composition or decomposition. Manure significantly boosts available P and exchangeable nutrients like K, Na, Ca, and Mg, particularly at PDM, where phosphorus availability notably increased. Higher TEB bases and CEC in manured soils suggest improved nutrient retention. Aluminium saturation decreased in manured soils, reducing potential toxicity and enhancing plant growth conditions. 3.2 Effects of sites on the potentially toxic elements after prolonged application of pig manure The study assesses the impact of prolonged pig manure on soil concentrations of potentially toxic elements across two sites, one where pig manure (PMS) was regularly applied, and an adjacent site (NPM) is presented in Table 2 . Elements such as Cu, Cd, Zn, Mn, Pb, and Fe were analyzed. The pig manure site displayed significantly higher levels of Cu, Cd, Zn, and Mn than NPM. Specifically, Cu and Zn levels at PMS were 0.476 mg/kg and 6.487 mg/kg, markedly higher than the 0.037 mg/kg and 0.140 mg/kg at NPM. In contrast, Pb and Fe concentrations were higher at NPM, with Pb at 0.231 mg/kg and Fe at 25.857 mg/kg, compared to 0.116 mg/kg and 22.056 mg/kg at PMS, respectively. Table 2 Effect of site on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Cu Cd Zn Mn Pb Fe Site .............................................................(mg/kg)............................................................ NPM 0.037b 0.006b 0.140b 4.299b 0.231a 25.857a PMS 0.476a 0.009a 6.487a 5.844a 0.116b 22.056b Means within a column followed by different letters indicate statistically significant differences (p ≤ 0.05); means followed by the same letter are not significantly different. 3.3 Effect of locations on the potentially toxic elements after prolonged application of pig manure Table 3 shows variations in metal concentrations across locations (FL, PDM, SJV) due to prolonged pig manure application. Para de Minas has the highest concentrations of Cu and Cd, with 0.347 mg/kg and 0.010 mg/kg, respectively, while FL has the lowest. Zinc peaks at PDM with 5.896 mg/kg and decreases through SJV to FL. Manganese trends are opposite, highest at FL with 8.546 mg/kg and lowest at SJV. The levels of Pb are relatively similar but slightly higher in FL than in PDM. Table 3 Effect of depth location on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Cu Cd Zn Mn Pb Fe Location .............................................................(mg/kg)............................................................ FL 0.153b 0.005b 1.107c 8.546a 0.195a 23.667a PDM 0.347a 0.010a 5.896a 4.285b 0.148b 23.769a SJV 0.270a 0.009a 2.939b 2.383c 0.178ab 24.433a Means within a column followed by different letters indicate statistically significant differences (p ≤ 0.05); means followed by the same letter are not significantly different. 3.4 Effect of depths on the potentially toxic elements after prolonged application of pig manure Table 4 reveals a general decrease in Cu, Cd, Zn, Mn, Pb, and Fe concentrations with increasing soil depth in soils treated with prolonged pig manure application. Copper levels start highest at the surface from 0.576 mg/kg and decline to 0.082 mg/kg at 70–100 cm depth. Cadmium decreases from 0.010 mg/kg at the surface to 0.005 mg/kg in the deepest layer. Zinc concentrations drop from 9.037 mg/kg in the topsoil to 0.276 mg/kg at the deepest layer. Manganese shows a notable decline from 12.306 mg/kg at 0–10 cm to 0.979 mg/kg at 70–100 cm soil depth. Lead varies less, slightly increasing to 0.214 mg/kg in the most profound depth, while Fe peaks at 31.712 mg/kg between 20–30 cm before decreasing at greater depths. Table 4 Effect of depth on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Means with the same letter (superscript) in the column for the same parameter are statistically not different, as determined by Tukey's test at a level of P ≤ 0.05. Cu Cd Zn Mn Pb Fe Depths .............................................................(mg/kg)............................................................ 0–10 0.576a 0.010a 9.037a 12.306a 0.163ab 27.378a 10–20 0.440a 0.009ab 6.533b 7.037b 0.155ab 29.272a 20–30 0.233b 0.008a-c 3.157c 4.862bc 0.147b 31.712a 30–50 0.123b 0.008a-c 0.607d 3.474cd 0.170ab 25.438ab 50–70 0.087b 0.006bc 0.272d 1.7711d 0.193ab 17.461bc 70–100 0.082b 0.005c 0.276d 0.979d 0.214a 12.479c 3.5 Interaction effects of locations and sites on the potentially toxic elements after prolonged application of pig manure Table 5 illustrates how location and site influence concentrations of potentially toxic elements in soils with prolonged pig manure application. Copper peaks at 0.653 mg/kg at PMS in PDM, with the lowest at 0.027 mg/kg at NPM in SJV. Cadmium's highest level is 0.017 mg/kg at PMS in PDM, with the lowest at 0.004 mg/kg at NPM in PDM. Zinc is highest, with a value of 11.664 mg/kg at PMS in PDM and lowest at NPM in SJV (0.065 mg/kg). Manganese varies, peaking at PMS in FL with a value of 1.133 mg/kg and lowest at NPM in SJV with 1.594 mg/kg. Lead is highest at NPM in FL with a of 0.315 mg/kg and lowest at PMS in SJV with a value of 0.068 mg/kg. Iron ranges from a high of 33.280 mg/kg at PMS in SJV to a low value of 15.587 mg/kg at NPM in SJV. Table 5 Interaction effect of location and site on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Cu Cd Zn Mn Pb Fe Location Site .............................................................(mg/kg)............................................................ FL NPM 0.041c 0.005cd 0.228c 5.960b 0.315a 25.657ab PMS 0.264b 0.004d 1.985c 11.133a 0.076c 21.678bc PDM NPM 0.042c 0.004d 0.127c 5.343b 0.092c 24.925b PMS 0.653a 0.017a 11.664a 3.228bc 0.204b 22.613bc SJV NPM 0.027c 0.009b 0.065c 1.594c 0.288a 15.587c PMS 0.512a 0.008bc 5.813b 3.172bc 0.068c 33.280a Means within a column followed by different letters indicate statistically significant differences (p ≤ 0.05); means followed by the same letter are not significantly different. 3.6 Interaction effects of locations and depths on the potentially toxic elements after prolonged application of pig manure Table 6 reveals how location and soil depth impact concentrations of potentially toxic elements in soils treated with pig manure. Copper concentrations decrease with depth, showing the highest levels in the top 10 cm. Cadmium concentrations are relatively stable across depths but slightly diminish deeper in the soil, with peak levels at PDM's surface. Zinc also decreases with depth across all locations. Manganese shows variable concentrations but is generally higher in upper depths, especially in PDM. Lead maintains moderate consistency across depths, with variations by location and highest concentrations in surface depths. Iron remains high at all depths, increasing notably with depth in SJV. Table 6 Interaction effect of location and depth on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Cu Cd Zn Mn Pb Fe Location Depth .............................................................(mg/kg)............................................................ FL 0–10 0.312b-d 0.006cd 4.050def 21.726a 0.152b 29.189a-d 10–20 0.31bcd 0.007bcd 1.577ef 10.443b 0.165ab 32.793a 20–30 0.122cd 0.005cd 0.646f 8.710bc 0.168ab 31.546ab 30–50 0.068cd 0.004cd 0.200f 6.131b-e 0.171ab 27.073a-d 50–70 0.058cd 0.004cd 0.086f 2.815cde 0.23ab 12.245de 70–100 0.048d 0.003d 0.081f 1.454de 0.294a 9.159e PDM 0–10 0.643ab 0.015a 13.239a 8.440bc 0.178ab 29.023a-d 10–20 0.642ab 0.011abc 12.012ab 7.886bc 0.105b 24.512a-e 20–30 0.441abc 0.009a-d 7.921b-d 4.231c-e 0.101b 29.147a-d 30–50 0.180cd 0.013ab 1.260ef 3.129cde 0.155ab 27.461a-d 50–70 0.057cd 0.007b-d 0.406f 1.400de 0.171ab 18.601a-e 70–100 0.122cd 0.005cd 0.536f 0.626e 0.179ab 13.866c-e SJV 0–10 0.773a 0.011abc 9.823a-c 6.753b-d 0.160ab 23.922a-e 10–20 0.370b-d 0.010ab-d 6.010c-e 2.782c-e 0.196ab 30.513a-c 20–30 0.135cd 0.009ab-d 0.903f 1.646de 0.183ab 34.442a 30–50 0.120cd 0.006b-d 0.359f 1.160de 0.184ab 21.781a-e 50–70 0.130cd 0.008b-d 0.325f 1.098de 0.175ab 21.532a-e 70–100 0.091cd 0.007bcd 0.213f 0.856de 0.169ab 14.410b-e Means within a column followed by different letters indicate statistically significant differences (p ≤ 0.05); means followed by the same letter are not significantly different. 3.7 Interaction effects sites and depths on the potentially toxic elements after prolonged application of pig manure Table 7 highlights the interaction between site and depth on soil element concentrations. Copper, Cd, and Zn showed the highest concentrations at PMS in the top 0–10 cm, decreasing sharply with depth. The lowest values for these elements were consistently observed at NPM in deeper layers of 70–100 cm. Manganese peaked at PMS at 0–10 cm and decreased significantly with depth, with the lowest levels at NPM’s deepest depths. Lead concentrations varied but generally decreased with depth, showing an increase in the deepest depths at NPM. Iron levels were relatively consistent, with peak concentrations at 20–30 cm depths across sites, while the lowest concentrations were in the deepest depths. Table 7 Interaction effect of site and depth potentially toxic elements under prolonged application of pig manure in Brazilian soils Cu Cd Zn Mn Pb Fe Location Depth .............................................................(mg/kg)............................................................ NPM 0–10 0.045c 0.006bc 0.368d 9.001b 0.212abc 30.718ab 10–20 0.047c 0.008bc 0.185d 5.607bc 0.256a 29.251ab 20–30 0.043c 0.007bc 0.126d 4.542b-d 0.223ab 30.726ab 30–50 0.038c 0.006bc 0.081d 3.604cd 0.222ab 23.686a-c 50–70 0.026c 0.005bc 0.044d 2.022cd 0.224ab 11.021cd 70–100 0.022c 0.004c 0.038d 1.019cd 0.252a 6.935d PMS 0–10 1.107a 0.015a 17.707a 16.612a 0.115c-e 24.038a-c 10–20 0.833a 0.010ab 12.881b 8.468b 0.054e 29.294ab 20–30 0.422b 0.008bc 6.187c 5.183b-d 0.072de 29.294ab 30–50 0.207bc 0.009a-c 1.132d 3.343cd 0.1179b-e 27.191ab 50–70 0.138bc 0.007bc 0.501d 1.520cd 0.162a-d 23.900a-c 70–100 0.151bc 0.006bc 0.515d 0.939d 0.176ab-d 18.022b-d Means within a column followed by different letters indicate statistically significant differences (p ≤ 0.05); means followed by the same letter are not significantly different. 3.8 Interaction effects of the location by site by depths on the potentially toxic elements after prolonged application of pig manure Figures 3 to 8 detail the influence of locations, sites, and depths on the concentrations of PTEs in the soils. Each figure reflects measurements from different locations (FL, PDM, SJV) and compares PMS to NPM. Copper levels are consistently higher in PMS across all locations, with the highest concentrations in the topsoil and a general decrease with depth. The peak of Cu concentration, nearly 2 mg/kg, occurs in the PMS topsoil at SJV. Cadmium exhibits low concentrations across depths but shows higher variability in PMS, especially at the surface, where levels peak at 0.035 mg/kg in PDM. The concentrations of Mn are markedly higher at shallower depths in PMS, particularly at FL, where it reaches 30 mg/kg in the top 10 cm. This trend of high surface concentrations and a decrease in depth is consistent across locations. The levels of Pb are also higher in surface depths, decreasing with depth, with slight variations between PMS and NPM. Iron content is highest near the surface and decreases with depth. The decline in Fe concentration is less pronounced in SJV, showing relatively stable levels even at greater depths. The Fe distribution shows minimal differences between PMS and NPM. Zinc concentrations are low across most samples, with an exceptional spike in the top 10 cm of PDM, reaching up to 30 mg/kg, indicating significant accumulation in this soil depth compared to others. 4.0 Discussion 4.1 Initial physicochemical properties of the study areas The study across the locations in FL, PDM, and SJV in Fig. 3 demonstrates the impact of pig manure on soil physicochemical properties. Manure-treated soils exhibited decreased sand content and increased silt and clay, enhancing soil structure and water-holding capacity, a finding supported by Younas [ 42 ]. The decrease in bulk density, observed by Lal [ 43 ], (2015), points to improved porosity and root penetration. According to Joona et al. [ 44 ]. (2024), manure applications also increase pH and organic carbon, boosting fertility and microbial activity. Nutrient levels, including P, K, Ca, and Mg, were elevated, crucial for crop yields, as Sharpley et al. [ 45 ] noted. However, elevated levels of exchangeable Na posed risks to soil structure. Manure also increased TEB and CEC, enhancing nutrient retention [ 46 ]. High aluminium saturation is potentially toxic to plants, and management is needed to mitigate soil acidity and toxicity. 4.2 Prolonged application of pig manure on the potentially toxic elements of different under different sites, depths and ecosystems The concentration differences between PMS and NPM sites were notable, with Cu, Cd, Zn, and Mn significantly higher at PMS, likely from metals in pig feed accumulating in the soil [ 47 ]. Conversely, Pb and Fe were higher at NPM and potentially reduced at PMS; this might result from complexation or adsorption processes [ 48 ]. Copper and Cd levels were notably high at the PDM, possibly due to increased manure application or soil properties enhancing metal retention [ 49 ]. The high levels of Cd raise concerns for plant toxicity and food safety. The prevalent type of Zn at PDM and Mn in FL reflects local soil conditions and management practices affecting their mobility and availability [48. 50]. The vertical distribution of metals shows Cu and Cd concentrations decreasing with soil depth, indicating limited leaching at the soil surface[ 48 , 50 ]. Zinc and concentrations were also higher at the topsoil, which is crucial for biological processes but potentially toxic at high concentrations [ 50 ]. Lead remained relatively constant across depths but showed peaks in surface soils, reflecting its low solubility and strong retention, limiting downward movement [ 51 ]. Iron variability, influenced by redox conditions and pH, suggests these factors affect solubility and distribution [ 52 ]. Generally, the findings underscore the need to carefully manage manure and other organic amendments to mitigate the risk of heavy metal accumulation in soils. Phytoremediation and proper crop rotation can be effective strategies to manage and mitigate the impacts of these metals in agricultural soils, as suggested by [ 53 ] and supported by research on soil amendments that immobilize metals [ 54 ]. The study highlights the complex interplay of soil chemistry, manure management, and environmental safety in agriculture. 4.3 Interaction effects of the three factors on the potentially individual toxic elements Figures 3 to 8 detail the impact of location, site, and depth on the distribution of PTEs in soils from three Brazilian soils (FL, PDM, SJV). The data reveal higher Cu levels in PMS across all locations, reflecting Cu accumulation due to manure application [ 55 ]. Copper concentration decreases with depth (Fig. 3 ), highlighting its binding to organic matter and clay in topsoil, emphasizing the need for careful surface soil management [ 56 ]. As shown in Fig. 4 , Cadmium displays higher concentrations in PMS soils at the surface, particularly in PDM, influenced by manure's metal content, as corroborated by the work of Kubier et al. [ 57 ]. The consistent levels across depths suggest limited Cd leaching, aligning with findings that Cd remains primarily in topsoil [ 58 ]. As shown in Fig. 5 , Mn shows higher concentrations in the upper soil depths, especially in FL, reflecting direct nutrient applications and decreasing with depth [ 59 ]. This trend underscores the importance of considering soil depth and treatment type in nutrient management, particularly for essential micronutrients like Mn [ 59 ]. As detailed in Fig. 6 , the distribution of Pb varied among locations and sites. In FL and SJV, Pb levels were notably higher in NPM compared to PMS, and concentrations increased rather than decreased with depth. In PDM, Pb values in PMS were higher than NPM, showing variability rather than a clear decreasing trend with depth. The variability in Pb distribution across locations and sites indicates differences in soil properties, management, or historical inputs. Elevated Pb in deeper layers at FL and SJV under NPM suggests sources other than surface-applied manure, possibly historical or natural. In PDM, variable Pb levels under PMS highlight Pb mobility complexity, necessitating site-specific management assessments [ 60 ]. Iron content, as shown in Fig. 7 , exhibited variability across locations. In SJV, Fe peaked at intermediate soil depths (20–70 cm). In contrast, at FL and PDM, Fe concentrations were consistently higher in NPM than in PMS soils. Despite applying organic amendments, iron's levels are minimally affected due to its inherent soil properties and low mobility [ 61 ]. Zinc levels, affected by soil management practices, pH, and OM content, show higher concentrations at the surface in PDM (Fig. 8 ), likely from direct manure applications [ 62 ]. This highlights the complex interactions affecting Zn mobility and retention in agricultural soils. 5.0 Conclusion Incorporating pig manure (PM) into soil did not significantly enhance Fe and Mn content. Cu and Zn content, on the other hand, significantly increased with continuous manure application. According to the Soil Fertility Commission of Minas Gerais, the elevated Cu content did not exceed toxicity levels, meaning there was low short-term environmental risk. On the contrary, Zn levels exceeded high availability thresholds, evidencing the need for diligent tracking and regulation of the application of pig manure to avoid potential toxicity and ensure soil health. The increase in Zn levels points towards a pressing need for regulations to control manure use effectively. The study did not find remarkable elevations of Cd and Pb concentrations with prolonged manure application, but continued monitoring and comparative analysis to COPAM Resolution No. 166/2011 standards remain important. In future research, total metal concentrations should still be studied to improve understanding of potential environmental impacts. These toxic elements at low concentrations still pose considerable environmental risks due to their bioaccumulation within the food chain, which would harm ecosystems and human health. Therefore, effective management techniques for organic amendments, such as frequent soil analysis, cautious adjustment of the rate of manure application, and methods like phytoremediation, are needed to mitigate heavy metal accumulation in soil agriculture. The application of phytoremediation might reduce soil Cd concentration especially. Monitoring programs and environmental risk assessment are critical to controlling potential Pb pollution, particularly in intensively manured soils. Soil amendment studies that immobilize heavy metals can significantly lower their bioavailability, reducing risks to that extent. Training farmers on proper manure handling, the use of clean organic amendments, and nutrient dynamics, particularly Fe stratification in soils, is vital for Minas Gerais' sustainable management of soil health. Declarations Acknowledgements The authors appreciate the technical assistance from the Management and Conservation of Soil and Water Laboratory, Institute of Agrarian Science, Florestal Campus, Federal University of Vicosa, Minas Gerais, Brazil; and financial support from the Multi-user Center of the Federal University of Viçosa, Florestal Campus, Minas Gerais State; Research Support Foundation (FAPEMIG); National Council for Scientific and Technological Development (CNPq) and Funding Agency for Studies and Projects (FINEP). This acknowledgement will ensure that all contributors and supporters are duly recognized. Conflict of Interest The authors declare no conflicts of interest. Ethics declarations This work mainly concerns Evaluating Potentially Toxic Elements in Soils and does not involve any information on humans or animals; thus, an ethical statement is not applicable to the manuscript's context. Funding information This research was supported by funds from Núcleo Multiusuário da Universidade Federal de Viçosa (UFV) Campus Florestal, Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Fapemig), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Financiadora de Estudos e Projetos (Finep), and it was supported by a fellowship from the Nigeria Tertiary Education Trust Fund given to the fourth author for his postdoctoral research in Brazil. Authors´ Contribution Many people participated in this scientific report. The responsibilities were as follows: conceptualisation, DAFF, AJA, APL, and DMSO; methodology, DAFF and DMSO; validation and formal analysis, APL and DAFF; resources, DAFF and DMSO; data curation, AJA, DAFF and DMSO; writing-original draft preparation, APL and DAFF; writing-review and correction, AJA and DMSO; project administration, DAFF; and funding acquisition, DAFF and DMSO. All the authors have read and agreed to the published version of the manuscript. Clinical Trial Registration No clinical trial was recorded for the study. DATA AVAILABILITY The data that support this study's findings are available from Dr Adebayo Jonathan ADEYEMO, but restrictions apply to their availability. These data were used under license for the current study and are not publicly available. However, data are available from the authors upon reasonable request and with permission of Dr. Adebayo Jonathan Adeyemo. Consent to Publish Declaration Not applicable Consent to Participate Declaration Not applicable References Wang L, Li D (2024) Invited Review - Current status, challenges and prospects for pig production in Asia. Animal Bioscience 37(4):742–754. https://doi.org/10.5713/ab.23.0303 . Hötzel MJ, Vandresen B (2022) Brazilians' attitudes to meat consumption and production: Present and future challenges to the sustainability of the meat industry. 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Frontiers in Plant Science 13:1033092. https://doi.org/10.3389/fpls.2022.1033092 . Additional Declarations No competing interests reported. Supplementary Files supplementarymaterials.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 15 Apr, 2025 Editor assigned by journal 07 Apr, 2025 Reviews received at journal 05 Apr, 2025 Reviewers agreed at journal 29 Mar, 2025 Reviews received at journal 24 Mar, 2025 Reviewers agreed at journal 24 Mar, 2025 Reviewers agreed at journal 24 Mar, 2025 Reviewers invited by journal 24 Mar, 2025 Submission checks completed at journal 24 Mar, 2025 First submitted to journal 18 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6019209","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":433453805,"identity":"bd2108d8-bf2d-43d0-93ff-61be32c0854e","order_by":0,"name":"Ana Paula Lemos","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Ana","middleName":"Paula","lastName":"Lemos","suffix":""},{"id":433453806,"identity":"50a25eae-f849-4c56-a57f-5ac0e79d2242","order_by":1,"name":"Diego Antonio França Freitas","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Diego","middleName":"Antonio França","lastName":"Freitas","suffix":""},{"id":433453808,"identity":"615a47d0-5404-4168-a5ac-d3e6b5221eb4","order_by":2,"name":"Adebayo Jonathan Adeyemo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYFCCAwwSYJq98QFMgFgtPIcNIKoJa2GAapFIJlILf+Phhzc+ttlE80s+ZpP+UMMgx3cjge3hF3w2HDhmbDmzLS135uxkNiCHwVjyRgK7sQxerxwwk+ZtO5y74Xb+MYkDbAyJG4C2SEvg0SF/4Pg36b9t/3M33DwMtOUfQz1BLQYHzphJM7YdyN1wg5lN4mAbQ4IBUIvkBzxaDA+cKbbsOZecO7MnmdnibJ+E4cwzD9uk8XlF7sbxjTd+lNnl9rMfZrxR8c1Gnu948jHJH/j0SBxgYGBkQ3CBmLGBmQefFv4GIPEHTZARry2jYBSMglEw0gAAOzFXnCXGW7EAAAAASUVORK5CYII=","orcid":"","institution":"Federal University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Adebayo","middleName":"Jonathan","lastName":"Adeyemo","suffix":""},{"id":433453810,"identity":"70d777ed-215d-4ba8-871d-01e418f704cb","order_by":3,"name":"Dener Márcio Silva Oliveira","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Dener","middleName":"Márcio Silva","lastName":"Oliveira","suffix":""}],"badges":[],"createdAt":"2025-02-13 03:38:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6019209/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6019209/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":79266508,"identity":"4553e45a-c3f4-4957-a2f2-33934a14a9e5","added_by":"auto","created_at":"2025-03-26 10:10:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":19964,"visible":true,"origin":"","legend":"\u003cp\u003eThe sampling scheme used in each site using a 3 x 3 grid of 9 points 50 meters apart on a sample coverage of 1 hectare of land.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/c6ba3b9d4f1735a17a3f6cb6.png"},{"id":79264611,"identity":"cea170be-30ff-45b8-96d2-2c8108f5a6c3","added_by":"auto","created_at":"2025-03-26 09:54:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":343197,"visible":true,"origin":"","legend":"\u003cp\u003eMap of the study area in the Minas Gerais area of Brazil, indicating the locations, sites, and sampling points. PMS: Pig manure site NPM: Non-Pig manure site (Adjacent soil)\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/f669210fbfc5446a1ea6236f.png"},{"id":79264615,"identity":"79e104b0-dd2a-42a7-8f25-6a4360800f08","added_by":"auto","created_at":"2025-03-26 09:54:27","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":22611,"visible":true,"origin":"","legend":"\u003cp\u003eCopper levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). Bars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/649214d928a01bc9c8018235.png"},{"id":79264614,"identity":"52b7b5bf-9357-4154-a7a2-15d9c122439c","added_by":"auto","created_at":"2025-03-26 09:54:27","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":24469,"visible":true,"origin":"","legend":"\u003cp\u003eCadmium levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). \u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eBars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/4e147d2e3ab57fb1c2ebde43.png"},{"id":79264617,"identity":"774634ab-589b-40e6-b255-8d782b0d225a","added_by":"auto","created_at":"2025-03-26 09:54:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":23208,"visible":true,"origin":"","legend":"\u003cp\u003eManganese levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). \u003cstrong\u003eBars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/4ce940ee61d92c55edb97ee2.png"},{"id":79264616,"identity":"6d99484d-1ab2-4b5c-b38e-b5efc5c963cb","added_by":"auto","created_at":"2025-03-26 09:54:27","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":24494,"visible":true,"origin":"","legend":"\u003cp\u003eLead levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). Bars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/b8dfcfd86e1a4d6545baeef3.png"},{"id":79266510,"identity":"bafc393d-d040-460a-8092-f7d1591f1b46","added_by":"auto","created_at":"2025-03-26 10:10:27","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":24124,"visible":true,"origin":"","legend":"\u003cp\u003eIron levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). Bars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/eba01b062845a5a251a788b1.png"},{"id":79265520,"identity":"17fcfff4-a986-41b7-a9c4-4faafda2a52e","added_by":"auto","created_at":"2025-03-26 10:02:27","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":22569,"visible":true,"origin":"","legend":"\u003cp\u003eCopper levels in PMS and NPM soils across various sites and depths in Minas Gerais, Brazil, are shown with horizontal bars that represent the standard errors of the means (n = 9). Bars labeled with different letters within the same soil layer indicate statistically significant differences (p ≤ 0.05); bars with the same letter indicate no significant difference.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/bd93d44a3660d5accce490f9.png"},{"id":79266858,"identity":"679358f9-60cb-45c9-b804-fb13fd545bae","added_by":"auto","created_at":"2025-03-26 10:18:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2109184,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/be09b8be-0ff5-4554-b04f-fea7acbf9413.pdf"},{"id":79265518,"identity":"87f23b6c-1104-43ef-9bdb-0cbc3338ed81","added_by":"auto","created_at":"2025-03-26 10:02:27","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":20716,"visible":true,"origin":"","legend":"","description":"","filename":"supplementarymaterials.docx","url":"https://assets-eu.researchsquare.com/files/rs-6019209/v1/c2f4f3f902f6f678acf29863.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluating Potentially Toxic Elements Under Prolonged Application of Pig Manure in Brazilian Soils","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003ePig production is a significant global provider of animal protein for human consumption [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Although pork is the most consumed meat globally, it ranks third in Brazil after poultry and beef [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In early 2024, worldwide pig production was 114.15\u0026nbsp;million tons, surpassing poultry and beef production at 103.26\u0026nbsp;million and 59.48\u0026nbsp;million tons, respectively. Pork plays a significant role as a meat in Brazil, with 18 kg consumed per person in 2023. Brazil is likewise one of the largest pig-producing countries in the world, with 46.5\u0026nbsp;million animals in a herd, and production is projected to increase even more. Although there have been achievements, pig production is associated with massive environmental issues, specifically animal waste disposal, which is of extremely high risk in terms of pollution according to volume and chemical complexity [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. While to some, pig manure (PM) is an organic waste, other scholars consider PM as an essential resource in improving soil quality and plant productivity [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Its high nutritional content includes macronutrients such as nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) and essential micronutrients such as copper (Cu) and zinc (Zn), which are helpful during crop production [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Managed PM application can also increase soil physical parameters, promoting improved infiltration rate, lowering bulk density, erosion, and rising availability of soil moisture, P, and K, favouring crop growth [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Brazilian reports establish the agronomic value of PM-based fertilizers [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Despite its virtues, PM manufacturing surpasses soil absorption capacity for nutrients in compact farms, hence presenting the excess disposal issue [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eUnregulated application of PM risks the environment with the build-up of nutrients in the topsoil layer, mainly phosphorus, which has the potential to contaminate water bodies [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Furthermore, animal waste can harbour unwanted contaminants such as antibiotics, pathogens, and potentially toxic elements (PTEs) like heavy metals Cu, Zn, Fe, Mn, Co, and Cd [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. These elements harm the environment due to their toxicity and bioaccumulation tendency, which causes adversity to human health [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Animal manure has been recognized as a significant source of PTEs in agricultural soils [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Tiecher et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] found substantial Cu and Zn enrichment in surface soils after long-term PM application in Brazilian agrarian fields. Smanhotto et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] also reported Cu and Zn accumulation after annual PM disposal for 4\u0026ndash;22 years in western Santa Catarina. Matos et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] analyzed Brazilian soils in Barcarena and found Cu, Ni, Zn, and Hg at high concentrations above national safety levels. Most studies have examined the essential micronutrients and overlooked the availability and level of contamination of non-essential metals like Cd and Pb. Few studies have determined soil under realistic field conditions or sampled soil up to a depth of one meter.\u003c/p\u003e \u003cp\u003eThis study bridges these gaps by evaluating the long-term PM application effect on bioavailable PTE concentrations in soils from three sites in Minas Gerais State, Brazil. Findings provide the path for local farmers to adopt sustainable PM utilization to minimize toxic element release and soil pollution. Data collected on PTE fate in PM-amended soils in target regions of Minas Gerais will inform better waste management practices. This research will enhance knowledge of metal behaviour in treated soils, enabling sustainable production to minimize environmental pollution and enhance human health in the region.\u003c/p\u003e"},{"header":"2.0 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 A brief description of the study area\u003c/h2\u003e \u003cp\u003eThe present study was carried out at three different places, namely Florestal, Par\u0026aacute; de Minas, and S\u0026atilde;o Jos\u0026eacute; da Varginha, in Minas Gerais (MG) State of Brazil. Geographically, the district is situated between Latitude 19\u0026deg;52'42.81\" S, Longitude 44\u0026deg;24'46.79\" W; Latitude 19\u0026deg;47'34.27\" S, Longitude 44\u0026deg;37'32.35\" W; and Latitude 19\u0026deg;44'59.57\" S, Longitude 44\u0026deg;32'29.94\" W, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Altitudes in MG vary between 76 and 2892 m, with topography favourable for mesoscale circulations, which develop due to valley and mountain breezes [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Topography, land use, and land cover also play a crucial role in the climate of MG because it determines the region's microclimates. This was done within the state where the selected sites present a high production of pigs and presently occupy the third position as the largest based on pig production [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. According to Reboita et al. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], the climatic condition of the study areas corresponds to a tropical savanna region, with a marked dry spell throughout winter. The average annual temperature varies from 19.5 to 20.7\u0026deg;C, while the average annual rainfall ranges from 1306 to 1419 mm yearly [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The textural type of soil is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSoil physicochemical characteristics (0\u0026ndash;10) cm of the two sampling sites in each location\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003eLocations\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eFL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003ePDM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eSJV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePMS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNPM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePMS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNPM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePMS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNPM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSoil Classification (BSSC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eRed-yellow dystrophic latosol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eDystrophic haplic cambisol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eRed dystrophic latosol\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSand (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e38.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e38.37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSilt (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e32.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e11.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e14.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eClay (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e28.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e51.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e47.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBD (gcm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epH in water\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.32\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTOC (mg C ha\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAvail. P ( mgdm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1321.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e497.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5.78\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExch. K (mgdm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e239.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e521.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e168.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e178.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e79.56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExch. Na (mgdm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExch. Ca cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExch. Mg (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExch. Al (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTEB (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH\u0026thinsp;+\u0026thinsp;Al (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003et (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT (cmol\u003csub\u003ec\u003c/sub\u003edm\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003em (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e86.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e27.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e52.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eBSSC: Brazilian System of Soil Classification; BD: Bulk density; TOC: Total organic carbon; TEB: Total exchangeable bases; t: effective cation exchange capacity (ECEC); T: cation exchangeable capacity at pH\u003csub\u003e7.0\u003c/sub\u003e (CEC pH\u003csub\u003e7.0\u003c/sub\u003e); V: Base saturation; m: % aluminium saturation; H\u0026thinsp;+\u0026thinsp;Al: Total acidity. PMS: poultry manure site; NPM: non-pig manure.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFlorestal and S\u0026atilde;o Jos\u0026eacute; da Varginha (SJV) are located in the central metropolitan region of Belo Horizonte, while Para de Minas is in the central-western region of MG. A flat or gently undulating relief characterises the topography, while the Atlantic Forest and the Cerrado are the two biomes that cover these areas. However, the study is located within the limits of the Cerrado biome, with fragments of semideciduous seasonal forest occurrence[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Florestal soil is classified as Red-yellow Dystrophic latosol [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. S\u0026atilde;o Jos\u0026eacute; da Varginha (SJV) is a Cerrado biome, dominated by vegetation characteristic fragments of the ecotone, with species of semideciduous seasonal forest and Cerrado Sensu Stricto [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The soil is dominated by low-activity clay called Dystrophic Haplic Cambisol [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Physiogeographically, Par\u0026aacute; de Minas is located in the Atlantic Forest Biome [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, it is amid a phytogeographic transition with the Cerrado, with some areas predominating mountainous vegetation and others with semi-deciduous seasonal forest. The topography is also marked by a flat, gently undulating relief with Red Dystrophic Latosol. It is one of the cities that make up the Belo Horizonte Metropolitan Necklace. Its proximity to the capital and federal highways gives the city a strategic location for the flow of agricultural, livestock, and industrial products and easy access to important regions of the country, such as the Minas Triangle, S\u0026atilde;o Paulo, and Vit\u0026oacute;ria. This location favours the city's economic development, represented by a diversified economic base emphasising industrial activities and agribusiness.\u003c/p\u003e \u003cp\u003eCattle, poultry, and pig rearing are the most representative livestock activities in the three selected locations of the study areas. Of these, poultry and pig rearing are dominant [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], and all of these serve as their primary source of income. In the PDM area, pig manure application has evolved over 20 years, starting with surface applications from 1998 to 2008, transitioning to maize with surface-irrigated slurry, and then corn and beans from 2008 to 2019 using a hydro-roll irrigation system. Since 2019, corn has been planted annually with no crop rotations. Initially, pig manure in slurry was distributed via gravity and contour-based methods over 15 hectares at a rate of 7 litres/m\u003csup\u003e2\u003c/sup\u003e/week. Recently, only potassium was added to the manured fields. In SJV, slurry application methods vary between sprinklers and robust hoses over 6.5 hectares without specified dosage control. Previously used for pasture, these fields now support corn crops for three years, receiving a single chemical fertilizer application of 244 kg/ha NPK 6-30-10 the year before the study, with no liming reported. Post-harvest, fields remain fallow until the next planting season. The farming activities of the local people include conventional cropping, dominated by cassava (\u003cem\u003eManihot esculenta\u003c/em\u003e) and maize (\u003cem\u003eZea mays\u003c/em\u003e), soybean (\u003cem\u003eGlycine max\u003c/em\u003e (L.) Merrill), cotton (\u003cem\u003eGossypium herbaceum\u003c/em\u003e), eucalyptus (\u003cem\u003eEucalyptus globulus\u003c/em\u003e), sugarcane (\u003cem\u003eSaccharum officinarum\u003c/em\u003e), coffee (\u003cem\u003eCoffea arabica\u003c/em\u003e), bean (Phaseolus vulgaris L.), and potato (Solanum tuberosum), scattered tree crops like orange (\u003cem\u003eCitrus sinensis\u003c/em\u003e); these activities took place both in rainy and dry seasons as per the historical findings from the dwellers. The local conditions of the soil present medium vulnerability to environmental contamination by land use. According to Soares (2024), one should take care regarding the use, management, and conservation of the soil, including possible risks of contamination by PTEs.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Soil sampling and collection:\u003c/h2\u003e \u003cp\u003eThe study employed a chronosequence approach, specifically, two sites were identified in three different locations, with each location being two kilometres apart. These were an alternative agricultural land with a prolonged application of pig manure and a nearby site of native vegetation used as a reference. A chronosequence approach was used in this study since there was no long-term experiment on the set-up presented in this research. This approach is based on the supposition that space can substitute for time [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Soil chronosequences reveal how time influences soil formation and its interactions with climate, vegetation, microorganisms, and land use changes, enhancing understanding of soil development processes [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe sampling scheme of a 3 x 3 grid, consisting of 9 points 50 meters apart, was used on a sample coverage of 1 hectare of land on each site (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Six soil samples were collected along a 100-centimetre depth at each point, separated into sampling layers of 0\u0026ndash;10, 10\u0026ndash;20, 20\u0026ndash;30, 30\u0026ndash;50, 50\u0026ndash;70, and 70\u0026ndash;100 cm. A 130 x 130 x 130 (cm\u003csup\u003e3\u003c/sup\u003e) trench was opened at the centre to collect undisturbed and disturbed soil samples (P5). The soil was collected manually to a depth of 100 cm. At each of the four extreme points of the sampling grid (P1, P3, P7, and P9), a 40 x 40 x 40 (cm\u003csup\u003e3\u003c/sup\u003e) trench was dug, and soil samples were manually collected between 0\u0026ndash;10, 10\u0026ndash;20, and 20\u0026ndash;30 cm layers. A Dutch auger collected soil samples between 30\u0026ndash;50, 50\u0026ndash;70, and 70\u0026ndash;100 cm soil layers to avoid contamination. At the other points of the sampling grid (P2, P4, P6, and P8), collections were performed between 0\u0026ndash;10, 10\u0026ndash;20, 20\u0026ndash;30, 30\u0026ndash;50, 50\u0026ndash;70, and 70\u0026ndash;100 cm layers, using an auger. Composite samples were then taken from six distinctive layers, and these were repeated in all nine sampling points, in two sites and the three locations. The experiment units that contain three hundred and twenty-four (324) were later combined to make one hundred and eight (108) treatment combinations, arranged in 6 \u0026times; 2 \u0026times; 3, respectively representing the depths, sites, and locations, replicated nine times initially and later bulk to three. One part of the soil sample was packed in clean and sterilized polythene bags; later, the samples were sieved through 2 mm for the selected chemical analysis. All samples were immediately stored in well-labelled sealed plastic bags in a cooler and transported to the management of Soil and Water Conservation Laboratory, institute of Agrarian Science of Florestal campus, the Federal University of Vicosa, state of Minas Gerais- for the chemical determination within 3 days of sampling.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Laboratory analyses\u003c/h2\u003e \u003cp\u003eSoil samples were analyzed for pH using a 1 to 2.5 soil-to-water ratio. Potential acidity (H\u0026thinsp;+\u0026thinsp;Al) was assessed using McLean's [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] SMP single-buffer method, while available phosphorus was determined through the Mehlich-1 solution method [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Exchangeable potassium (K) and sodium (Na) were extracted similarly, with K and Na quantified by flame emission photometry [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Total organic carbon was measured by wet oxidation, involving 0.5 g of soil treated with potassium dichromate and sulfuric acid, heated at 170\u0026deg;C for 30 minutes, and titrated using ferrous ammonium sulfate with Ferroin indicator [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Calcium (Ca) and Mg were extracted using a 1 mol/L KCl solution, and their concentrations were determined by atomic absorption spectrometry [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Total N content was analyzed via Kjeldahl digestion [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], and CEC was measured using the ammonium acetate method [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Exchangeable Al was assessed using 1 mol/L KCl and titrated with 0.025 mol/L NaOH until the solution changed from yellow to blue [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Additional soil parameters such as the sum of total exchangeable bases, effective cation exchange capacity, cation exchange capacity at pH 7.0, base saturation, and Al saturation were calculated following Ribeiro et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Bulk density was determined using the volumetric ring method, where a known volume ring is filled with soil and weighed, allowing density calculation by dividing the soil mass by the ring volume [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Drying soil samples quantified soil moisture at 100\u0026ndash;105\u0026deg;C for 24 hours [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Analysis of the micronutrients\u003c/h2\u003e \u003cp\u003eReplicates soil samples collected from each depth and the three locations were air-dried, crushed in a porcelain mortar, and then sieved through a\u0026thinsp;\u0026lt;\u0026thinsp;2 mm mesh stainless sieve. The potential toxic elements of interest (Cu, Zn, Fe, Mn, Cd, and Pb). The metals were determined using the Mehlich-1 extraction method to separate the metals present in the soil. This technique is widely used in soil analysis when a chemical evaluation of the amount of metals available for plant absorption is desired [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The use of the Mehlich-1 solution for the extraction of available metals in the soil is due to its simplicity of preparation and the fact that it presents a strong correlation between the content of metals absorbed by plants and the content available in the soil[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. This method involves extracting elements from the soil using a solution containing 0.05 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e diluted hydrochloric acid (HCl) and 0.0125 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e hydrogen tetraoxosulphate (vi) acid (H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e) in a soil: extractor ratio of 1:5. The methodology used to extract the elements were adapted from Embrapa\u0026acute;s Manual of Chemical Analysis of Soils, Plants and Fertilizers [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. The reading was determined by an AA 7000 atomic absorption spectrophotometer, Shimadzu, with air/acetylene flame, installed at the Multiuser Center of the Federal University of Vi\u0026ccedil;osa, Florestal Campus, Minas Gerais, Brazil. Quality assurance of the atomic absorption spectrophotometry (AAS) analysis was maintained by calibrating the spectrophotometer with certified standard solutions before each analytical batch. Additionally, blank samples and reference standards were regularly analyzed during each set of measurements to confirm instrument accuracy, sensitivity, and reproducibility. Each soil sample was analyzed in replicates to ensure the precision and reliability of the results.\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.5 Statistical analysis\u003c/b\u003e: Data obtained were analyzed using variance analysis with the general linear model of Minitab 17.0 edition. Collected data were analyzed to test for the main and interaction effects of prolonged sites amended with pig manure under different depths and locations on measured and selected soil parameters. Tukey HSD test was the statistical post-hoc applied to check for significant differences among means obtained at a 5% probability level of confidence. The results were presented in tables and graphs. Microsoft Excel 2007 calculates treatments\u0026acute; means and standard errors before plotting the graphs.\u003c/p\u003e \u003c/div\u003e"},{"header":"3.0 Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Initial soil physicochemical properties of the study area\u003c/h2\u003e\n \u003cp\u003eThe study analyzes soil properties across three Brazilian sites (FL, PDM, SJV), comparing manure-treated areas with adjacent non-manure soils, is presented in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. It was revealed that manure application slightly reduces sand content while increasing silt and clay, suggesting that manure impacts soil texture by enhancing finer soil fractions. Manure generally lowers soil bulk density and increases soil acidity in untreated soils. Total organic carbon levels varied, with higher TOC in manured soils at FL and SJV but lower at PDM, possibly due to differences in manure composition or decomposition. Manure significantly boosts available P and exchangeable nutrients like K, Na, Ca, and Mg, particularly at PDM, where phosphorus availability notably increased. Higher TEB bases and CEC in manured soils suggest improved nutrient retention. Aluminium saturation decreased in manured soils, reducing potential toxicity and enhancing plant growth conditions.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Effects of sites on the potentially toxic elements after prolonged application of pig manure\u003c/h2\u003e\n \u003cp\u003eThe study assesses the impact of prolonged pig manure on soil concentrations of potentially toxic elements across two sites, one where pig manure (PMS) was regularly applied, and an adjacent site (NPM) is presented in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. Elements such as Cu, Cd, Zn, Mn, Pb, and Fe were analyzed. The pig manure site displayed significantly higher levels of Cu, Cd, Zn, and Mn than NPM. Specifically, Cu and Zn levels at PMS were 0.476 mg/kg and 6.487 mg/kg, markedly higher than the 0.037 mg/kg and 0.140 mg/kg at NPM. In contrast, Pb and Fe concentrations were higher at NPM, with Pb at 0.231 mg/kg and Fe at 25.857 mg/kg, compared to 0.116 mg/kg and 22.056 mg/kg at PMS, respectively.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEffect of site on the potentially toxic elements under prolonged application of pig manure in Brazilian soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.037b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.140b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.299b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.231a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.857a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePMS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.476a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.487a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.844a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.116b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.056b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eMeans within a column followed by different letters indicate statistically significant differences (p\u0026thinsp;\u0026le;\u0026thinsp;0.05); means followed by the same letter are not significantly different.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 Effect of locations on the potentially toxic elements after prolonged application of pig manure\u003c/h2\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows variations in metal concentrations across locations (FL, PDM, SJV) due to prolonged pig manure application. Para de Minas has the highest concentrations of Cu and Cd, with 0.347 mg/kg and 0.010 mg/kg, respectively, while FL has the lowest. Zinc peaks at PDM with 5.896 mg/kg and decreases through SJV to FL. Manganese trends are opposite, highest at FL with 8.546 mg/kg and lowest at SJV. The levels of Pb are relatively similar but slightly higher in FL than in PDM.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEffect of depth location on the potentially toxic elements under prolonged application of pig manure in Brazilian soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003eCu\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026nbsp;Location\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.153b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.107c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.546a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.195a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.667a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePDM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.347a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.010a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.896a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.285b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.148b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.769a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSJV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.270a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.939b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.383c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.178ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.433a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eMeans within a column followed by different letters indicate statistically significant differences (p\u0026thinsp;\u0026le;\u0026thinsp;0.05); means followed by the same letter are not significantly different.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e\u003cstrong\u003e3.4 Effect of depths on the potentially toxic elements after prolonged application of pig manure\u003c/strong\u003e\u003c/h2\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e reveals a general decrease in Cu, Cd, Zn, Mn, Pb, and Fe concentrations with increasing soil depth in soils treated with prolonged pig manure application. Copper levels start highest at the surface from 0.576 mg/kg and decline to 0.082 mg/kg at 70\u0026ndash;100 cm depth. Cadmium decreases from 0.010 mg/kg at the surface to 0.005 mg/kg in the deepest layer. Zinc concentrations drop from 9.037 mg/kg in the topsoil to 0.276 mg/kg at the deepest layer. Manganese shows a notable decline from 12.306 mg/kg at 0\u0026ndash;10 cm to 0.979 mg/kg at 70\u0026ndash;100 cm soil depth. Lead varies less, slightly increasing to 0.214 mg/kg in the most profound depth, while Fe peaks at 31.712 mg/kg between 20\u0026ndash;30 cm before decreasing at greater depths.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEffect of depth on the potentially toxic elements under prolonged application of pig manure in Brazilian soils Means with the same letter (superscript) in the column for the same parameter are statistically not different, as determined by Tukey\u0026apos;s test at a level of P\u0026thinsp;\u0026le;\u0026thinsp;0.05.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;Cu\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDepths\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.576a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.010a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.037a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.306a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.163ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.378a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.440a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.533b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.037b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.155ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.272a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.233b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.157c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.862bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.147b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.712a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.123b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.607d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.474cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.170ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.438ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.087b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.272d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.7711d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.193ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.461bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.082b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.276d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.979d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.214a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.479c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003e3.5 Interaction effects of locations and sites on the potentially toxic elements after prolonged application of pig manure\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e illustrates how location and site influence concentrations of potentially toxic elements in soils with prolonged pig manure application. Copper peaks at 0.653 mg/kg at PMS in PDM, with the lowest at 0.027 mg/kg at NPM in SJV. Cadmium\u0026apos;s highest level is 0.017 mg/kg at PMS in PDM, with the lowest at 0.004 mg/kg at NPM in PDM. Zinc is highest, with a value of 11.664 mg/kg at PMS in PDM and lowest at NPM in SJV (0.065 mg/kg). Manganese varies, peaking at PMS in FL with a value of 1.133 mg/kg and lowest at NPM in SJV with 1.594 mg/kg. Lead is highest at NPM in FL with a of 0.315 mg/kg and lowest at PMS in SJV with a value of 0.068 mg/kg. Iron ranges from a high of 33.280 mg/kg at PMS in SJV to a low value of 15.587 mg/kg at NPM in SJV.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eInteraction effect of location and site on the potentially toxic elements under prolonged application of pig manure in Brazilian soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLocation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.041c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.228c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.960b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.315a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.657ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePMS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.264b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.004d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.985c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.133a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.076c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.678bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePDM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.042c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.004d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.127c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.343b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.092c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.925b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePMS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.653a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.017a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.664a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.228bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.204b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.613bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSJV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.027c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.065c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.594c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.288a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.587c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePMS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.512a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.813b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.172bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.068c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.280a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003eMeans within a column followed by different letters indicate statistically significant differences (p\u0026thinsp;\u0026le;\u0026thinsp;0.05); means followed by the same letter are not significantly different.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003e3.6 Interaction effects of locations and depths on the potentially toxic elements after prolonged application of pig manure\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e reveals how location and soil depth impact concentrations of potentially toxic elements in soils treated with pig manure. Copper concentrations decrease with depth, showing the highest levels in the top 10 cm. Cadmium concentrations are relatively stable across depths but slightly diminish deeper in the soil, with peak levels at PDM\u0026apos;s surface. Zinc also decreases with depth across all locations. Manganese shows variable concentrations but is generally higher in upper depths, especially in PDM. Lead maintains moderate consistency across depths, with variations by location and highest concentrations in surface depths. Iron remains high at all depths, increasing notably with depth in SJV.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab6\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eInteraction effect of location and depth on the potentially toxic elements under prolonged application of pig manure in Brazilian soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026nbsp;Location\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDepth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.312b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.050def\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.726a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.152b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.189a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.31bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.007bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.577ef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.443b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.165ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.793a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.122cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.646f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.710bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.168ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.546ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.068cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.004cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.200f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.131b-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.171ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.073a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.058cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.004cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.086f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.815cde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.23ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.245de\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.048d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.003d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.081f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.454de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.294a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.159e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePDM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.643ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.015a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.239a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.440bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.178ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.023a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.642ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.011abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.012ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.886bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.105b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.512a-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.441abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.921b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.231c-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.101b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.147a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.180cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.013ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.260ef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.129cde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.155ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.461a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.057cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.007b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.406f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.400de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.171ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.601a-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.122cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.536f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.626e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.179ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.866c-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSJV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.773a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.011abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.823a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.753b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.160ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.922a-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.370b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.010ab-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.010c-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.782c-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.196ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.513a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.135cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009ab-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.903f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.646de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.183ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34.442a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.120cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.359f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.160de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.184ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.781a-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.130cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.325f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.098de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.175ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.532a-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.091cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.007bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.213f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.856de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.169ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.410b-e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003eMeans within a column followed by different letters indicate statistically significant differences (p\u0026thinsp;\u0026le;\u0026thinsp;0.05); means followed by the same letter are not significantly different.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003e3.7 Interaction effects sites and depths on the potentially toxic elements after prolonged application of pig manure\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e highlights the interaction between site and depth on soil element concentrations. Copper, Cd, and Zn showed the highest concentrations at PMS in the top 0\u0026ndash;10 cm, decreasing sharply with depth. The lowest values for these elements were consistently observed at NPM in deeper layers of 70\u0026ndash;100 cm. Manganese peaked at PMS at 0\u0026ndash;10 cm and decreased significantly with depth, with the lowest levels at NPM\u0026rsquo;s deepest depths. Lead concentrations varied but generally decreased with depth, showing an increase in the deepest depths at NPM. Iron levels were relatively consistent, with peak concentrations at 20\u0026ndash;30 cm depths across sites, while the lowest concentrations were in the deepest depths.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab7\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eInteraction effect of site and depth potentially toxic elements under prolonged application of pig manure in Brazilian soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026nbsp;Location\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDepth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e.............................................................(mg/kg)............................................................\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.045c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.368d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.001b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.212abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.718ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.047c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.185d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.607bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.256a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.251ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.043c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.007bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.126d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.542b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.223ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.726ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.038c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.081d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.604cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.222ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.686a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.026c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.044d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.022cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.224ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.021cd\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.022c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.004c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.038d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.019cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.252a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.935d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePMS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.107a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.015a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.707a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.612a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.115c-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.038a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u0026ndash;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.833a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.010ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.881b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.468b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.054e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.294ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u0026ndash;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.422b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.008bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.187c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.183b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.072de\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.294ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.207bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.009a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.132d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.343cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1179b-e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.191ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u0026ndash;70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.138bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.007bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.501d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.520cd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.162a-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.900a-c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u0026ndash;100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.151bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.515d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.939d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.176ab-d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.022b-d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003eMeans within a column followed by different letters indicate statistically significant differences (p\u0026thinsp;\u0026le;\u0026thinsp;0.05); means followed by the same letter are not significantly different.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003e3.8 Interaction effects of the location by site by depths on the potentially toxic elements after prolonged application of pig manure\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFigures \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e to \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e detail the influence of locations, sites, and depths on the concentrations of PTEs in the soils. Each figure reflects measurements from different locations (FL, PDM, SJV) and compares PMS to NPM. Copper levels are consistently higher in PMS across all locations, with the highest concentrations in the topsoil and a general decrease with depth. The peak of Cu concentration, nearly 2 mg/kg, occurs in the PMS topsoil at SJV. Cadmium exhibits low concentrations across depths but shows higher variability in PMS, especially at the surface, where levels peak at 0.035 mg/kg in PDM. The concentrations of Mn are markedly higher at shallower depths in PMS, particularly at FL, where it reaches 30 mg/kg in the top 10 cm. This trend of high surface concentrations and a decrease in depth is consistent across locations. The levels of Pb are also higher in surface depths, decreasing with depth, with slight variations between PMS and NPM. Iron content is highest near the surface and decreases with depth. The decline in Fe concentration is less pronounced in SJV, showing relatively stable levels even at greater depths. The Fe distribution shows minimal differences between PMS and NPM. Zinc concentrations are low across most samples, with an exceptional spike in the top 10 cm of PDM, reaching up to 30 mg/kg, indicating significant accumulation in this soil depth compared to others.\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4.0 Discussion","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Initial physicochemical properties of the study areas\u003c/h2\u003e \u003cp\u003eThe study across the locations in FL, PDM, and SJV in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrates the impact of pig manure on soil physicochemical properties. Manure-treated soils exhibited decreased sand content and increased silt and clay, enhancing soil structure and water-holding capacity, a finding supported by Younas [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The decrease in bulk density, observed by Lal [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], (2015), points to improved porosity and root penetration. According to Joona et al. [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. (2024), manure applications also increase pH and organic carbon, boosting fertility and microbial activity. Nutrient levels, including P, K, Ca, and Mg, were elevated, crucial for crop yields, as Sharpley et al. [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e] noted. However, elevated levels of exchangeable Na posed risks to soil structure. Manure also increased TEB and CEC, enhancing nutrient retention [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. High aluminium saturation is potentially toxic to plants, and management is needed to mitigate soil acidity and toxicity.\u003c/p\u003e \u003cp\u003e \u003cb\u003e4.2 Prolonged application of pig manure on the potentially toxic elements of different under different sites, depths and ecosystems\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe concentration differences between PMS and NPM sites were notable, with Cu, Cd, Zn, and Mn significantly higher at PMS, likely from metals in pig feed accumulating in the soil [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. Conversely, Pb and Fe were higher at NPM and potentially reduced at PMS; this might result from complexation or adsorption processes [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Copper and Cd levels were notably high at the PDM, possibly due to increased manure application or soil properties enhancing metal retention [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. The high levels of Cd raise concerns for plant toxicity and food safety. The prevalent type of Zn at PDM and Mn in FL reflects local soil conditions and management practices affecting their mobility and availability [48. 50]. The vertical distribution of metals shows Cu and Cd concentrations decreasing with soil depth, indicating limited leaching at the soil surface[\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. Zinc and concentrations were also higher at the topsoil, which is crucial for biological processes but potentially toxic at high concentrations [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. Lead remained relatively constant across depths but showed peaks in surface soils, reflecting its low solubility and strong retention, limiting downward movement [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]. Iron variability, influenced by redox conditions and pH, suggests these factors affect solubility and distribution [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. Generally, the findings underscore the need to carefully manage manure and other organic amendments to mitigate the risk of heavy metal accumulation in soils. Phytoremediation and proper crop rotation can be effective strategies to manage and mitigate the impacts of these metals in agricultural soils, as suggested by [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] and supported by research on soil amendments that immobilize metals [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. The study highlights the complex interplay of soil chemistry, manure management, and environmental safety in agriculture.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Interaction effects of the three factors on the potentially individual toxic elements\u003c/h2\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e to \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e detail the impact of location, site, and depth on the distribution of PTEs in soils from three Brazilian soils (FL, PDM, SJV). The data reveal higher Cu levels in PMS across all locations, reflecting Cu accumulation due to manure application [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]. Copper concentration decreases with depth (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), highlighting its binding to organic matter and clay in topsoil, emphasizing the need for careful surface soil management [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, Cadmium displays higher concentrations in PMS soils at the surface, particularly in PDM, influenced by manure's metal content, as corroborated by the work of Kubier et al. [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]. The consistent levels across depths suggest limited Cd leaching, aligning with findings that Cd remains primarily in topsoil [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, Mn shows higher concentrations in the upper soil depths, especially in FL, reflecting direct nutrient applications and decreasing with depth [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e]. This trend underscores the importance of considering soil depth and treatment type in nutrient management, particularly for essential micronutrients like Mn [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e]. As detailed in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the distribution of Pb varied among locations and sites. In FL and SJV, Pb levels were notably higher in NPM compared to PMS, and concentrations increased rather than decreased with depth. In PDM, Pb values in PMS were higher than NPM, showing variability rather than a clear decreasing trend with depth. The variability in Pb distribution across locations and sites indicates differences in soil properties, management, or historical inputs. Elevated Pb in deeper layers at FL and SJV under NPM suggests sources other than surface-applied manure, possibly historical or natural. In PDM, variable Pb levels under PMS highlight Pb mobility complexity, necessitating site-specific management assessments [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. Iron content, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, exhibited variability across locations. In SJV, Fe peaked at intermediate soil depths (20\u0026ndash;70 cm). In contrast, at FL and PDM, Fe concentrations were consistently higher in NPM than in PMS soils. Despite applying organic amendments, iron's levels are minimally affected due to its inherent soil properties and low mobility [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e]. Zinc levels, affected by soil management practices, pH, and OM content, show higher concentrations at the surface in PDM (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e), likely from direct manure applications [\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e]. This highlights the complex interactions affecting Zn mobility and retention in agricultural soils.\u003c/p\u003e \u003c/div\u003e"},{"header":"5.0 Conclusion","content":"\u003cp\u003eIncorporating pig manure (PM) into soil did not significantly enhance Fe and Mn content. Cu and Zn content, on the other hand, significantly increased with continuous manure application. According to the Soil Fertility Commission of Minas Gerais, the elevated Cu content did not exceed toxicity levels, meaning there was low short-term environmental risk. On the contrary, Zn levels exceeded high availability thresholds, evidencing the need for diligent tracking and regulation of the application of pig manure to avoid potential toxicity and ensure soil health. The increase in Zn levels points towards a pressing need for regulations to control manure use effectively.\u003c/p\u003e \u003cp\u003eThe study did not find remarkable elevations of Cd and Pb concentrations with prolonged manure application, but continued monitoring and comparative analysis to COPAM Resolution No. 166/2011 standards remain important. In future research, total metal concentrations should still be studied to improve understanding of potential environmental impacts. These toxic elements at low concentrations still pose considerable environmental risks due to their bioaccumulation within the food chain, which would harm ecosystems and human health.\u003c/p\u003e \u003cp\u003eTherefore, effective management techniques for organic amendments, such as frequent soil analysis, cautious adjustment of the rate of manure application, and methods like phytoremediation, are needed to mitigate heavy metal accumulation in soil agriculture. The application of phytoremediation might reduce soil Cd concentration especially.\u003c/p\u003e \u003cp\u003eMonitoring programs and environmental risk assessment are critical to controlling potential Pb pollution, particularly in intensively manured soils. Soil amendment studies that immobilize heavy metals can significantly lower their bioavailability, reducing risks to that extent. Training farmers on proper manure handling, the use of clean organic amendments, and nutrient dynamics, particularly Fe stratification in soils, is vital for Minas Gerais' sustainable management of soil health.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors appreciate the technical assistance from the Management and Conservation of Soil and Water Laboratory, Institute of Agrarian Science, Florestal Campus, Federal University of Vicosa, Minas Gerais, Brazil; and financial support from the Multi-user Center of the Federal University of Viçosa, Florestal Campus, Minas Gerais State; Research Support Foundation (FAPEMIG); National Council for Scientific and Technological Development (CNPq) and Funding Agency for Studies and Projects (FINEP). This acknowledgement will ensure that\u0026nbsp;all contributors and supporters are duly recognized.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work mainly concerns Evaluating Potentially Toxic Elements in Soils and does not involve any information on humans or animals; thus, an ethical statement is not applicable to the manuscript's context.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by funds from Núcleo Multiusuário da Universidade Federal de Viçosa (UFV) Campus Florestal, Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Fapemig), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Financiadora de Estudos e Projetos (Finep), and it was supported by a fellowship from the Nigeria Tertiary Education Trust Fund given to the fourth author for his postdoctoral research in Brazil.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors´ Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMany people participated in this scientific report. The responsibilities were as follows: conceptualisation, DAFF, AJA, APL, and DMSO; methodology, DAFF and DMSO; validation and formal analysis, APL and DAFF; resources, DAFF and DMSO; data curation, AJA, DAFF and DMSO; writing-original draft preparation, APL and DAFF; writing-review and correction, AJA and DMSO; project administration, DAFF; and funding acquisition, DAFF and DMSO. All the authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo clinical trial was recorded for the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDATA AVAILABILITY\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support this study's findings are available from Dr Adebayo Jonathan ADEYEMO, but restrictions apply to their availability. These data were used under license for the current study and are not publicly available. However, data are available from the authors upon reasonable request and with permission of Dr. Adebayo Jonathan Adeyemo.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWang L, Li D (2024) Invited Review - Current status, challenges and prospects for pig production in Asia. 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Frontiers in Plant Science 13:1033092. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fpls.2022.1033092\u003c/span\u003e\u003cspan address=\"10.3389/fpls.2022.1033092\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Pig manure, toxic metals, PTEs, Brazilian soils","lastPublishedDoi":"10.21203/rs.3.rs-6019209/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6019209/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePig manure (PM) is crucial for animal protein production, especially in Brazil, where pork is widely consumed. However, managing animal waste remains a challenge. While PM serves as a soil amendment, it may also introduce potentially toxic elements (PTEs), such as heavy metals, into agricultural soils. Few studies address the impact of long-term PM application on the availability of these metals at various soil depths. This study analysed copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), cadmium (Cd), and lead (Pb) in soils with prolonged PM use in Florestal (FL), Par\u0026aacute; de Minas (PDM), and S\u0026atilde;o Jos\u0026eacute; da Varginha (SJV), Brazil. Samples were collected from six soil depths using the Mehlich-1 method, with element concentrations determined via atomic absorption spectrophotometry. Data were analysed using ANOVA and Duncan\u0026rsquo;s test (5% probability). The results showed that soils with PM had higher levels of Cu and Zn, with Cd elevated only in PDM. Fe and Mn showed no significant differences, whilst Pb was higher in FL and PDM soils without PM. PM application increased Cu and Zn levels but did not significantly affect the other elements. In conclusion, long-term PM use elevates Cu and Zn levels in soils, posing potential risks of Zn toxicity. Public policies are needed to regulate PM usage, reduce soil pollution, and promote sustainable waste management for environmental health.\u003c/p\u003e","manuscriptTitle":"Evaluating Potentially Toxic Elements Under Prolonged Application of Pig Manure in Brazilian Soils","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-26 09:54:23","doi":"10.21203/rs.3.rs-6019209/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-15T04:43:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-07T05:35:35+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-05T05:17:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"240192593016283548679241576605308237483","date":"2025-03-29T09:49:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-25T01:11:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"56548533806020569096618585087901871503","date":"2025-03-25T00:54:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"127867860130720242919249556573977814290","date":"2025-03-24T08:39:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-24T08:34:43+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-24T04:51:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Applied Sciences","date":"2025-03-18T13:49:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14721a48-9d91-4181-bd0a-b71c46c12b94","owner":[],"postedDate":"March 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-04-25T06:08:20+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-26 09:54:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6019209","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6019209","identity":"rs-6019209","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}