Effects of different exogenous additives on humification and microbial community during tomato straw composting process

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Four treatments were tested: T1 (tomato straw + 0.5% EM bacterial agent), T2 (tomato straw + 10% biochar + 0.5% EM), T3 (tomato straw + 10% superphosphate + 0.5% EM), and T4 (tomato straw + 10% phosphogypsum + 0.5% EM). Results showed that these additives extended the high-temperature phase and improved compost maturity, with T2 being the most effective. T2 exhibited the highest increase in humic acid (127.01%) and the greatest degradation of organic matter (63%) and cellulose (69.82%), outperforming the control (p < 0.05). Microbial analysis revealed that Firmicutes , Actinobacteriota , and Proteobacteria dominated the phylum level, while Bacillus, Weissella, Staphylococcus, and Halocella were key genera. Corynebacterium was identified as the main microorganism responsible for spoilage and maturation. This study highlights biochar’s role in enhancing humification in tomato straw composting. Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Ecology/Agri ecology compost exogenous additives tomato straw microbial community humification Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction As societies develop and populations increase, the demand for agricultural development and yield improvement also rises 1 . Continuous agricultural development generates large amounts of organic waste, making its proper management a critical issue. Aerobic composting is the primary method for managing agricultural organic waste. Its products not only improve soil physical and chemical properties but also serve as a substitute for inorganic fertilizers, promoting agricultural production 2 . It is widely recognized as an economical, environmentally friendly, and potentially sustainable method for treating various organic wastes 3 , 4 . However, the composting of agricultural organic waste faces several challenges, including long maturation cycles, nitrogen loss, and the production of unstable or immature compost. Immature compost contains lower nutrient levels, higher amounts of pathogenic bacteria and insect eggs, and can also be toxic to plants 1 . Humus is a critical indicator of compost maturity and plays a key role in the composting process 5 . Therefore, improving the quality of compost products and shortening the composting process are essential for achieving effective organic waste recycling. Humus-rich compost plays a crucial role in soil conditioning and promoting plant growth 6 , 7 . To accelerate the composting process and enhance humification, researchers have manipulated aeration 8 , inoculated with microbial agents, controlled turning frequency 9 , applied hydrothermal pretreatment 10 , and used mulch films 11 , among other strategies. In practical composting, due to limited control over raw materials and process parameters, many researchers have added various additives to enhance organic matter decomposition and humification 12 . These additives include calcium superphosphate 13 , phosphogypsum 13 , and biochar 14 . Wang et al. added 10% biochar to wine lees compost and found that it reduced nitrogen loss and accelerated microbial community succession, thus enhancing the composting process 15 . Lei et al. reported that adding 10% phosphogypsum to manure compost promoted microbial nitrogen conversion, significantly improved compost quality, and shortened the composting duration. Zhao et al. added 18% calcium superphosphate to chicken manure compost, finding that it effectively promoted ammonium and nitrate nitrogen accumulation and altered microbial nitrogen fixation strategies 16 . However, these studies were limited to single comparisons and did not identify the optimal additives for enhancing the composting process and humification. This study aimed to investigate the effects of various additives on the physicochemical properties, degree of decomposition, and microbial community in tomato straw compost during the composting process. The objectives of this study were: (1) to assess the impact of additives on the physicochemical properties and decomposition degree of the compost; (2) to identify optimal additives for improving compost quality and accelerating the composting process; and (3) to explore the correlation between physicochemical properties and key microorganisms under different additives. The study's results can enhance the composting process and recycling of organic waste, providing valuable insights for future research. 2. Materials and methods 2.1 Test materials and experimental design In this experiment, tomato straw was collected from a greenhouse in Yangling, Shaanxi Province, China, and ground to a 100-mesh size after drying. The EM bacterial agent was supplied by Henan Henkun Animal Husbandry Science and Technology Co., containing over 80 types of microorganisms across 10 genera. Biochar, in the form of agricultural wheat straw biochar powder, was purchased from Goodwill Sino-Austria. Calcium superphosphate was purchased from Hebei Xianzheng Agricultural Science and Technology Co. Phosphogypsum, primarily composed of CaSO₄·2H₂O, was purchased from Suzhou Xinqing Technology Co. Five treatments were designed for the experiment: T1 (straw + 0.5% microbial agent), T2 (straw + 10% biochar + 0.5% microbial agent), T3 (straw + 10% calcium superphosphate + 0.5% microbial agent), T4 (straw + 10% phosphogypsum + 0.5% microbial agent), and CK (blank control group with no treatments). All additives were added based on the dry weight percentage of the initial raw material. The experiment used a 300L homemade forced-ventilated static reactor for aerobic fermentation. The water content of the pile was adjusted to 60% using distilled water. Intermittent aeration was applied: 10 minutes of aeration followed by 50 minutes of cessation, with an aeration rate of 0.3 L/(L·min). The compost was turned at various stages during the composting process. Compost samples (approximately 200 g, fresh weight) were collected and divided into two portions. One portion was used for physicochemical parameters, elemental analysis, and lignocellulosic material determination, while the other portion was used for microbial analysis. 2.2 Determination of physical and chemical properties Digital temperature sensors (Shenzhen Shenghuaxuan Technology Co., Ltd., Shenzhen, China) were installed at three positions (top, middle, and bottom) of the homemade compost tank, and ambient temperature was recorded simultaneously. Both compost and ambient temperatures were measured using an MT-8X multi-channel temperature recorder (Shenzhen Shenghuaxuan Technology Co., Ltd., China). The average temperatures at 9:00 a.m., 2:00 p.m., and 7:00 p.m. were recorded as the daily temperatures. The samples were dried at 105°C for 24 hours to determine the water content 17 . The sample weight was determined by first placing an empty aluminum box in an oven at 105°C until dry, then adding a known amount of sample to the box to measure the initial weight, and drying the sample in the oven at 105°C for 12 hours before recording the final weight after cooling. Moisture content was calculated based on the initial and final weights. pH and electrical conductivity (EC) values were measured using a pH meter and an EC meter (Shanghai Inian Precision Instruments Co., Ltd.), with a 1:10 (w/v, sample: water) ratio for fresh samples. The samples (DW) were mixed with distilled water at a 1:10 (w/v) ratio and shaken in a thermostatic oscillator at 120 rpm for 1 hour. After filtering the samples through filter paper, pH and EC values were measured using a pH meter (OHAUS ST10) and an EC meter (OHAUS ST20), both made in China. A seed germination test was performed using the aqueous extract prepared as described. Five milliliters of supernatant were placed in a glass container with filter paper, and 20 cabbage seeds were evenly distributed. The seeds were incubated in the dark at 25°C for 48 hours. Distilled water was used as a control, and the seed germination index (GI) was calculated according to the following formula: $$\:\text{G}\text{I}\left(\text{%}\right)=\frac{\text{G}\text{e}\text{r}\text{m}\text{i}\text{n}\text{a}\text{t}\text{i}\text{o}\text{n}\:\text{r}\text{a}\text{t}\text{e}\:\text{o}\text{f}\:\text{t}\text{r}\text{e}\text{a}\text{t}\text{e}\text{d}\:\text{s}\text{e}\text{e}\text{d}\text{s}\:\left(\text{%}\right)\times\:\text{S}\text{e}\text{e}\text{d}\:\text{r}\text{o}\text{o}\text{t}\:\text{l}\text{e}\text{n}\text{g}\text{t}\text{h}}{\:\text{G}\text{e}\text{r}\text{m}\text{i}\text{n}\text{a}\text{t}\text{i}\text{o}\text{n}\:\text{r}\text{a}\text{t}\text{e}\:\:\text{o}\text{f}\:\text{c}\text{o}\text{n}\text{t}\text{r}\text{o}\text{l}\:\text{s}\text{e}\text{e}\text{d}\text{s}\:\left(\text{%}\right)\times\:\text{S}\text{e}\text{e}\text{d}\:\text{r}\text{o}\text{o}\text{t}\:\text{l}\text{e}\text{n}\text{g}\text{t}\text{h}}\left(1\right)$$ NH₄⁺-N was determined using the colorimetric method, and NO₃⁻-N was determined using the spectrophotometric method 20 . Organic matter was quantified by burning the samples at 550°C for 8 hours 21 . The absorbance of FA and HA components was measured at 465 nm and 665 nm using a UV-Vis spectrophotometer (WFH-201B, Shanghai Intan Precision Instrument Co., Ltd.) 22 . Cellulose, hemicellulose, and lignin content were determined according to the method described by Sajid et al 23 . Cellulose content was determined using the Van’s detergent method. 2.3 Scanning electron microscope analysis before and after straw degradation The samples were cleaned with distilled water, air-dried, and subsequently observed under a scanning electron microscope (Hitachi, Japan, S-3400 N) to identify any changes. To ensure proper fixation, the samples were mounted under vacuum using double-sided conductive tape and coated with a thin layer of gold 24 . Finally, the samples were observed and analyzed at an accelerating voltage of 10 kV and a filament current of 2.7 A. 2.4 DNA extraction and sequencing analysis Samples were collected on days 0, 5, 19, 40, and 65 of composting. The microbial community diversity was characterized using high-throughput sequencing, and genomic DNA was extracted from 0.5 g of compost using the E.Z.N.A. Stool DNA Kit (D4015, Omega Inc., USA). DNA was extracted by 1% agarose gel electrophoresis and quantified using a NanoDrop™ 2000 Spectrophotometer. PCR amplification was conducted with universal bacterial primers 338F: 5´-ACTCCTACGGGGAGGCAGCA-3´ and 806R: 5´-GGACTACHVGGGGTWTCTAAT-3´, as well as fungal primers ITS1F: 5´-CTTGGTCATTTAGAGGAAGTAA-3´ and ITS2: 5´-GCTGCGTTCTTCATCGATGC-3´. PCR products were purified with AMPure XT (Beckman Coulter Genomics, Danvers, MA, USA) and quantified using a Qubit (Invitrogen, Waltham, MA, USA) according to the method described by Li et al. The purified PCR products were evaluated using an Agilent 2100 Bioanalyzer (USA) and an Illumina library quantification kit (Kapa Biosciences, Woburn, MA, USA) to assess the size and quantity of the amplified libraries. Identification and sequencing were carried out on the NovaSeq PE250 platform (LC-Bio Technology Co., Ltd., Hangzhou, China). 2.5 Statistical analysis Data from the composting experiment were analyzed using SPSS 26.0 (IBM, USA) to calculate the mean and standard deviation for each treatment. A one-way analysis of variance (ANOVA) was performed to assess differences between treatments, with statistical significance set at p < 0.05. Data were visualized and plotted using Origin 2018 (OriginLab Corp., USA). 3. Results and discussion 3.1 Effect of different additives on the physical and chemical properties of the heap 3.1.1 Temperature Temperature is a key indicator in the composting of agricultural organic waste, reflecting the degradation efficiency of organic matter and the extent of pile decomposition 25 . Based on temperature changes, the composting process can be divided into four stages: warming, high temperature, cooling, and putrefaction 26 . As shown in Fig. 1 a, the temperature change trend in all treatments is consistent: the temperature rises rapidly to a peak and then gradually decreases. The rapid temperature increase at the beginning of composting is primarily due to the metabolism and reproduction of aerobic microorganisms, which consume easily degradable organic matter and release substantial energy 27 . The high temperature stage (> 55°C) lasted for 11 days (CK), 17 days (T1), 15 days (T2), 15 days (T3), and 15 days (T4) for each treatment, meeting the composting requirement of maintaining temperatures above 55°C for over 7 days 28 . As the temperature rises, microbial activity in the heap is inhibited, the decomposition rate of organic waste decreases, and the heap temperature begins to drop. Once easily degradable substances in the heap are exhausted through microbial decomposition, the temperature approaches ambient levels, indicating the completion of composting 29 . The temperature of the pile with the additive was slightly higher than that of the CK treatment, but the difference was not statistically significant. 3.1.2 pH The pH trends were similar across all treatments during the composting process (Fig. 1 b). In the early stages of composting, pH increased due to the decomposition of organic matter, ammonification of organic nitrogen, and the formation and dissolution of ammonia 30 . The pH values for all treatments peaked on day 11 at 8.64 (CK), 8.65 (T1), 8.90 (T2), 8.46 (T3), and 8.55 (T4), consistent with the findings of Pan et al. (2018). Between days 11 and 14, the organic acids produced by microbial reactions 31 , along with the volatilization and humification of NH₃ 32 , caused a decrease in pH for all treatments. Subsequent pH increases were due to the degradation of organic acids or proteins and nitrification 33 , 34 . At the end of composting, the pH values of the treatments were 9.11 (CK), 9.02 (T1), 9.20 (T2), 8.74 (T3), and 8.88 (T4), respectively. The relatively high pH in the T2 treatment was primarily due to the alkaline nature of the added biochar, which has higher porosity and specific surface area, facilitating ammonia uptake and raising the pH. 3.1.3 EC This study investigates the potential effects of electrical conductivity (EC) on salinity content in compost substrates, as well as its impact on seed germination and plant growth 35 . As shown in Fig. 1 c, at the beginning of composting, as the pile temperature increases, microorganisms consume a large amount of nutrients in ionic form, leading to a decrease in EC 36 . On day 8, the EC values reached their lowest levels in CK (3.92 mS/cm), T1 (3.96 mS/cm), T2 (4.10 mS/cm), T3 (4.25 mS/cm), and T4 (4.24 mS/cm). As composting progresses, the microbial decomposition of the pile releases large amounts of soluble salts 37 , causing a gradual increase in EC. From day 48 onwards, the volatilization of small molecules and the complexation reactions during humification stabilized the final EC of the heap 38 . Eventually, the EC values reached a steady state at 5.10 mS/cm for CK, 5.14 mS/cm for T1, 4.90 mS/cm for T2, 5.62 mS/cm for T3, and 5.23 mS/cm for T4. At the beginning of composting, EC values differed between treatments due to variations in the nature of the additives (p<0.05). At the end of composting, the T2 treatment exhibited the lowest EC, primarily due to the strong adsorption capacity of biochar on ions, which reduced the concentration of soluble salts 39 . Higher EC values in the T3 and T4 treatments were attributed to an increase in SO 4 2- , Ca 2+ , Mg 2+ , and PO 4 3- ions due to the addition of additives 32 , leading to an elevated EC. 3.1.4 GI The germination index (GI) is primarily used to assess the biotoxicity and maturity of compost. It increases as toxic substances decompose during the composting process 40 . At the start of composting, the GI of all treatments remained low (< 50%)(Fig. 1 d). By day 26, GI values increased and reached 80% in all treatments, except for CK (75.11%), indicating that the compost had matured and was no longer phytotoxic 30 . During the first 26 days of composting, GI values increased rapidly in all treatments. This increase may be attributed to the biodegradation of phytotoxic substances (e.g., volatile fatty acids and ammonium) and the accumulation of humus 30 . By the end of composting, the GI of each treatment reached its maximum value: 98.45% for CK, 105.65% for T1, 121.26% for T2, 110.48% for T3, and 115.57% for T4. The differences in GI values between treatments reflected variations in compost quality. 3.2 Effect of different additives on nitrogen, organic matter, HA and FA in the heap 3.2.1 Ammonium nitrogen The NH 4 + -N content increased rapidly in all treatments at the beginning of composting, peaking on day 14 with values of 3800.04 mg/kg for CK, 3527.59 mg/kg for T1, 2473.38 mg/kg for T2, 2919.77 mg/kg for T3, and 2785.34 mg/kg for T4 (Fig. 2 a). This increase is primarily due to the degradation of organic matter by microorganisms early in the composting process, coupled with increased ammonification and the inhibition of nitrification at high temperatures. These factors promote NH 4 + production and NH 3 volatilization in the compost heap 1 . NH 4 + -N content gradually decreased during composting and reached its lowest value at the end of the process: 1146.94 mg/kg in CK, 1375.97 mg/kg in T1, 791.85 mg/kg in T2, 926.70 mg/kg in T3, and 949.88 mg/kg in T4. The NH 4 + -N content continued to decrease, likely due to ammonification leading to NH 3 volatilization, as well as increased microbial nitrification and nitrogen fixation 29 . By the end of composting, NH 4 + -N levels remained higher in CK (1146.94 mg/kg) and T1 (1375.97 mg/kg) than in the other treatments. The decrease in NH 4 + -N content during the late stage of composting may be due to two factors: (1) Excess nitrogen is released as NH 3 (NH 4 + → NH 3 ↑ + H + ), and (2) Nitrification by nitrifying bacteria: NH 4 + + 2O 2 → NO 3 - + H 2 O + 2H + . 3.2.2 Nitrate nitrogen Nitrate is crucial for agricultural production as it serves as the primary source of nitrogen for most plants 41 . During the initial phase of composting, the NO 3 - -N content in all treatments remained stable (Fig. 2 b). However, as composting progressed, the NO 3 - -N content increased in all treatments, reaching higher levels at the end: CK (16717.32 mg/kg), T1 (1730.59 mg/kg), T2 (1936.08 mg/kg), T3 (1796.03 mg/kg), and T4 (1827.55 mg/kg). The lack of significant change in NO 3 - -N at the beginning of composting may be attributed to high ammonia levels and elevated temperatures, which inhibit nitrifying bacteria activity 42 . This effect persisted until day 26. As the temperature of the compost pile decreased, nitrifying bacteria became active again, promoting nitrification (Xu et al., 2024). This facilitated the conversion of NH 4 + -N to NO 3 - -N, leading to a significant increase in NO 3 - -N content (p < 0.05). At the end of composting, T2 treatment exhibited the highest NO 3 - -N content, suggesting that biochar may create a microenvironment that enhances the nitrification process 43 , 44 . 3.2.3 Humic acid The main component of humus is humic acid (HA), which reduces phytotoxicity and enhances compost quality. The HA content gradually increased throughout the composting process 6 . As shown in Fig. 3 a, the HA content in the compost pile increased by 83.54% (CK), 106.18% (T1), 127.01% (T2), 122.60% (T3), and 111.61% (T4) by the end of composting. The HA content was higher in the T2, T3, and T4 treatments. This suggests that the addition of biochar, exogenous microorganisms, and calcium superphosphate promotes HA formation during composting 45 . 3.2.4 Fulvic acid The decrease in FA and soluble organic carbon content is attributed to microbial degradation during the composting process 46 . In comparison with HA, FA content gradually decreased across all treatments throughout the composting process. Notably, the most rapid decrease occurred during the first 0–8 days of composting (Fig. 3 b). The T2 treatment exhibited the largest decrease in FA (64.25%), followed by T1 (51.08%), T4 (50.65%), CK (46.71%), and T3 (43.76%). The rapid decline in FA during the early stage of composting is primarily due to microorganisms utilizing readily available organic matter (i.e., FA) as an energy source 47 . Additionally, unstable humus components (FA) can be converted into stable components (HA) 46 , 48 . The gradual decrease in FA indicates a reduction in readily available organic carbon, leading to increased compost stability. By the end of the composting process, the FA content stabilized at low levels: 7.86 g/kg (CK), 7.81 g/kg (T1), 3.62 g/kg (T2), 7.50 g/kg (T3), and 4.47 g/kg (T4). 3.2.5 Organic matter Figure 3 c shows the changes in organic matter across the five treatments during the composting process. The highest OM content was observed in the initial feedstock, after which it decreased in all treatments. The decline was rapid during the first 8 days of composting, followed by a slowdown. By the end of composting, OM degradation percentages were 39%, 41%, 63%, 53%, and 58% in CK, T1, T2, T3, and T4, respectively. A positive feedback relationship between OM degradation and composting temperature was observed, which was linked to microbial activity 49 . T2, T3, and T4 exhibited higher and longer temperature increases and thermophilic periods compared to CK and T1. This suggests that biochar, phosphogypsum, and superphosphate enhanced microbial activity, accelerated OM consumption, and promoted compost maturation. T2 exhibited the highest maturation and OM degradation in the final compost, indicating that microbial activity in T2 was higher than in the other treatments. 3.3 Effect of different treatments on the change of lignocellulose content in the heaps The cellulose content in each treatment followed a similar trend, with a rapid decrease at the beginning, followed by a gradual slowdown in degradation as composting progressed. This may be attributed to higher temperatures in the early stages, which enhanced microbial activity, promoting cellulose degradation and accelerating the overall degradation rate 50 . The cellulose content decreased gradually in all treatments. At the end of composting, the relative cellulose content was 14.35% (CK), 13.89% (T1), 10.85% (T2), 12.25% (T3), and 11.66% (T4). The degradation rates at the end of composting were CK (62.61%), T1 (59.34%), T2 (69.82%), T3 (69.10%), and T4 (68.76%) (Fig. 4 a). The changes in hemicellulose content across all treatments are shown in Fig. 4 b. The hemicellulose content in all treatments continuously decreased during composting and stabilized by the end. These results are consistent with those of Wang et al 51 , who composted a mixture of maitake and pig manure. In their study, microorganisms utilized hemicellulose as a carbon source, leading to a reduction in hemicellulose content 52 . In this study, the rate of hemicellulose degradation was faster in all treatments during the first 0–19 days of composting. The degradation during this period accounted for 51.6–68.9% of the total hemicellulose loss. This may be due to higher temperatures and increased microbial activity, which accelerated the decomposition of hemicellulose 63 . At the end of composting, the hemicellulose content was 2.93% (CK), 3.02% (T1), 1.84% (T2), 2.19% (T3), and 2.03% (T4). Lignin is resistant to degradation due to its insoluble, irregular, and highly branched structure 53 . Its degradation products are precursors for the formation of humic substances (HS) 54 . The initial relative lignin content was similar across all treatments and increased rapidly during composting, peaking at 16.02% (CK), 16.39% (T1), 18.67% (T2), 17.86% (T3), and 16.93% (T4) on day 40 (Fig. 4 c). The increase in lignin content in all treatments can be attributed to the more rapid degradation of readily available organic matter (e.g., soluble sugars, proteins, hemicellulose, and cellulose) compared to lignin, resulting in the accumulation of lignin 55 , 56 . The lignin content then decreased, and at the end of composting, the relative lignin content in T2 was 16.09% higher than that in CK (13.27%), T1 (14.52%), T3 (15.33%), and T4 (15.97%). 3.4 Analysis of the effect of different treatments on the effectiveness of tomato straw composting The tomato straw composting process was completed after 65 days. Table 1 presents the maturation indices for each treatment at the end of composting. The key indices include pH, EC, NH 4 + -N, NO 3 − -N, humic acid, fulvic acid, organic matter, hemicellulose content, cellulose content, and lignin content. The data indicated that exogenous additives extended the high-temperature phase of composting and increased the degree of decomposition by the end. Biochar had the most significant effect. The biochar addition treatment (T2) significantly increased the humic acid content by 127.01% and enhanced the degradation rates of organic matter and cellulose to 63% and 69.82%, respectively, outperforming the control group. Table 1 Selected compost maturity parameters at the end of composting. Parameters CK T1 T2 T3 T4 pH 9.112 ± 0.09 9.02 ± 0.02 9.195 ± 0.02 8.743 ± 0.06 8.876 ± 0.07 EC(mS/cm) 5.10 ± 0.01 5.14 ± 0.01 4.90 ± 0.06 5.62 ± 0.08 5.23 ± 0.03 GI (%) 98.45 ± 2.61 105.65 ± 3.68 121.26 ± 8.96 110.48 ± 4.99 115.57 ± 2.40 NH 4 + -N (mg/kg) 1146.94 ± 12.42 1375.97 ± 25.60 791.85 ± 10.10 926.7 ± 25.78 949.88 ± 39.05 NO 3 − -N (mg/kg) 1617.32 ± 49.46 1730.23 ± 23.60 1936.08 ± 36.50 1796.03 ± 42.50 1827.55 ± 29.22 Humic-acid (g/kg) 21.18 ± 0.60 23.69 ± 1.10 28.25 ± 0.40 26.65 ± 0.78 25.37 ± 1.26 Fulvic-acid (g/kg) 7.86 ± 0.08 7.81 ± 1.48 3.62 ± 0.42 7.5 ± 1.87 4.47 ± 1.50 OM (g/kg) 326.77 ± 2.97 316.63 ± 14.71 197.41 ± 20.41 247.70 ± 14.03 229.28 ± 11.49 Hemicellulose content (%) 2.93 ± 1.23 3.02 ± 1.10 1.84 ± 1.34 2.19 ± 0.25 2.04 ± 0.63 Cellulose content (%) 14.35 ± 1.85 13.90 ± 1.03 10.85 ± 3.39 12.25 ± 0.81 11.66 ± 1.50 Lignin content (%) 13.27 ± 0.31 14.52 ± 0.30 16.09 ± 1.09 15.34 ± 0.32 15.97 ± 0.01 T1: straw + 0.5% microbial agent; T2: straw + 10% biochar + 0.5% microbial agent; T3: straw + 10% calcium superphosphate + 0.5% microbial agent; T4: straw + 10% phosphogypsum + 0.5% microbial agent; CK: blank control group without treatment. Results are the mean of three replicates + standard deviation. (EC: Electrical conductivity, NH 4 + -N: Ammonium nitrogen, NO 3 − -N: Nitrate nitrogen; OM: Organic matter) 3.5 Effect of different additives on the microstructure of the stack material Scanning electron microscopy observations revealed that the degree of decomposition on the surface of tomato straw varied across treatments. The surface of straw without composting treatment was smoother and more organized than that of the composted straw (Fig. 5 a). After composting, the straw surface became rough, and the original lignocellulose structure was damaged, resulting in an uneven, partially broken, porous, and loose appearance 1 (Fig. 5 b-f). In contrast, biochar-treated tomato straw exhibited larger surface voids and a rougher surface with debris. This is due to biochar's large surface area and porous nature, which improve the composting environment and provide physical support for microbial growth, thereby enhancing organic matter degradation and humification 57 . These changes contribute to the thorough decomposition of the straw. Scanning electron microscopy observations further revealed that composting treatments with different additives were more favorable for the humification of tomato straw. 3.6 Changes in microbial communities during the composting process 3.6.1 Bacterial diversity The composting process of tomato straw is significantly influenced by differences between treatments. The relative abundance of relevant microorganisms, which drive the degradation of agricultural organic wastes during composting, exhibited dynamic changes throughout the process. To assess the effect of exogenous additives on the microbial community during tomato straw composting, the relative abundance was analyzed at the bacterial phylum and genus levels. The relative abundance of bacterial phyla across different treatments is shown in Fig. 6 a. The top 10 bacterial phyla with the highest relative abundance include Firmicutes (75.47%-79.5%), Actinobacteriota (13.37%-16.27%), Proteobacteria (4.58%-6.80%), Planctomycetota (0.02%-0.41%), Gemmatimonadota (0.06%-0.15%), Patescibacteria (0.01%-0.05%), Bacteroidota (0.12%-0.77%), Verrucomicrobiota (0.16%-0.32%), Myxococcota (0.02%-0.1%), and Chloroflexi (0.01%-0.12%), which together account for more than 98% of the total bacterial phyla. Firmicutes not only exhibit high lignocellulose degradation capacity but also demonstrate strong tolerance to adverse conditions during composting, which enhances the degradation of tomato straw 1 . However, by the end of the composting process, the relative abundance of Firmicutes across treatments decreased to 9.81%-20.84%. A similar result was reported byWang et al., (2022), and Peng et al. (2021) 59 also found similar results when zeolite and calcium superphosphate were used as additives in the pig manure composting process.In the mature compost samples, Bacteroidota (1.37%-5.37%) was identified as a major phylum, with the ability to break down cellulose, hemicellulose, and lignin 60 . Proteobacteria primarily contribute to carbon cycling and the mineralization of nitrogenous organic matter during composting 61 . In the early stages, they degrade proteins and starch, and as composting progresses, both Proteobacteria and Actinobacteriota increase in abundance (10.79%-15.64%) and begin to decompose cellulose, likely due to their ability to degrade other organic matter and their thermophilic nature 62 . Actinobacteriota , which is known for its strong cellulose and lignin degradation capabilities, plays a significant role in compost maturation and humification, with its relative abundance closely correlated to temperature changes in the compost pile 63 . It is commonly used as an indicator of compost maturity. Gemmatimonadota also aids in cellulose and protein hydrolysis during composting 64 . The dominant phyla in the composting process exhibit variations due to the influence of exogenous additives or environmental factors, which in turn affect the overall maturity of the compost. Significant differences in microbial composition at the genus level can be observed both between treatments and between different time points within the same treatment (Fig. 6 b). The top 10 genera by relative abundance across the six treatments were Bacillus , Weissella , Corynebacterium , Staphylococcus , Halocella , S0134_terrestrial_group_unclassified , Bacillales_unclassified , Bacillaceae_unclassified , Planctomycetales_unclassified , and Sinibacillus . Bacillus exhibited the highest relative abundance across all treatments. The relative abundance of Bacillus was initially low at the start of the composting process (0.5–1.02%) but gradually increased during composting (18.59–37.88%). It became the dominant genus in the high-temperature stage and significantly contributed to lignocellulose degradation. The relative abundance of Bacillus gradually decreased as composting progressed, likely due to the reduction of available nutrients. Bacillus may also utilize degradation byproducts to promote the formation of humic acid and xanthate organic compounds in the compost 65 . Weissella (25.13–35.80%) and Staphylococcus (20.00-28.32%) dominated the compost warming phase. Staphylococcus played a key role in transforming the humus fraction, thereby increasing the accumulation of AK content (Xu et al., 2024). Halocella is a mesophilic bacterium with low relative abundance during the warming and high-temperature phases of composting. Its abundance increases as temperature decreases, and it primarily degrades tough materials such as cellulose 66 . 3.6.2 Redundancy analysis (RDA) Temperature changes in the bacterial community were primarily positively correlated with Weissella and Staphylococcus (Fig. 7 a). This indicates that these two microorganisms play a role in promoting the composting temperature, which may be related to their strong degradation of organic matter.These microorganisms were also positively correlated with NH 4 + -N, cellulose, hemicellulose, organic matter (OM), and fatty acids (FA). pH, electrical conductivity (EC), and germination index (GI) were positively correlated with Corynebacterium , S0134_terrestrial_group_unclassified , Bacillus , Planctomycetales_unclassified , and Halocella , indicating that these microorganisms play a role in promoting compost maturation. Nitrate (NO3–N), humic acids (HA), and lignin were positively correlated with Corynebacterium , S0134_terrestrial_group_unclassified , Bacillus (unclassified), Planctomycetales_unclassified , and Halocella . The correlation between key microorganisms in the composting process and indicators of compost decay and maturation can be further examined using RDA. This further supports the role of microorganisms in promoting compost decay and maturation. 3.6.3 Mental analysis The maturity and humification of compost are influenced not only by its physicochemical properties but also by the associated microbial communities. Figure 7 b presents the Mantel test results of compost physicochemical properties and key microorganisms on the maturity and humification during tomato straw composting. The germination index (GI) and hemicellulose in tomato straw compost showed a significant positive correlation (p < 0.05), indicating that hemicellulose plays a key role in reducing compost toxicity during composting. Humic acid (HA) was positively correlated with NO 3 − -N, organic matter (OM), hemicellulose, and Corynebacterium (p < 0.05). This suggests that the decrease in nitrate nitrogen and OM content during composting reflects the degree of humification, while the positive correlation between hemicellulose, Corynebacterium , and organic acids (OA) indicates their role in promoting HA formation. The key factors and microorganisms influencing the maturation and humification of tomato straw compost were further identified through the Mantel test. 4. Conclusion This study examined the effects of exogenous additives—biochar, phosphogypsum, and calcium superphosphate—on microbial communities and humification during tomato straw composting. The results indicated that exogenous additives prolonged the high-temperature stage of composting and enhanced the degree of humification, with biochar having the most pronounced effect. The biochar addition treatment (T2) significantly increased the humic acid content by 127.01%, and enhanced the degradation rates of organic matter (63%) and cellulose (69.82%), outperforming the control. In microbial communities, Firmicutes , Actinobacteriota , and Proteobacteria were the dominant phyla, playing key roles in lignocellulose degradation, and carbon and nitrogen cycling. Further RDA and Mantel test analysis revealed that Corynebacterium was the key microorganism promoting compost humification and maturation. This study demonstrated the beneficial effect of biochar on tomato straw compost humification, providing a scientific basis for the resource utilization and sustainable development of agricultural organic waste. Declarations Competing interests The authors declare no competing interests. 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Cite Share Download PDF Status: Published Journal Publication published 08 Dec, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 12 May, 2025 Reviews received at journal 09 May, 2025 Reviewers agreed at journal 28 Apr, 2025 Reviewers agreed at journal 26 Apr, 2025 Reviews received at journal 13 Feb, 2025 Reviewers agreed at journal 30 Jan, 2025 Reviewers agreed at journal 29 Jan, 2025 Reviewers invited by journal 29 Jan, 2025 Editor assigned by journal 29 Jan, 2025 Editor invited by journal 07 Jan, 2025 Submission checks completed at journal 06 Jan, 2025 First submitted to journal 25 Dec, 2024 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-5710860","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":399069807,"identity":"33bcccd6-9972-493e-89be-014ced02188e","order_by":0,"name":"Luolin Shu","email":"","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Luolin","middleName":"","lastName":"Shu","suffix":""},{"id":399069808,"identity":"564206aa-bdb2-4967-b734-e8338a8a277e","order_by":1,"name":"Yuanyuan Yang","email":"","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Yuanyuan","middleName":"","lastName":"Yang","suffix":""},{"id":399069809,"identity":"27194257-2252-451c-b9fe-87cb016f2f09","order_by":2,"name":"Xue Zheng","email":"","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Xue","middleName":"","lastName":"Zheng","suffix":""},{"id":399069810,"identity":"6027579d-e6a7-478d-8569-eaecb58fcf80","order_by":3,"name":"Qi Chen","email":"","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Qi","middleName":"","lastName":"Chen","suffix":""},{"id":399069811,"identity":"947a8e1c-9a18-41df-9736-a9ae9367c7e7","order_by":4,"name":"Zhenchao Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEElEQVRIiWNgGAWjYLACxgYgIQHEH4CYHcThIVYL4wyQ6gOkaGHmIUaLwfGzh1/+3GGTxz+7+eFj2x2H5XkkEhgfvG1jkDfHpeVMXpqF5Jm0Yok7x4yNc88cNuyRSGA2nNvGYLizAYeWAzlmBoZthxM3SCSYSee23WbcL5HAJs3bxpBgcACHlvNvzAwS2/4DtaR/k7Zsu20PtIX9N14tN3KMHxxsOwDUkmMmzdh2OxGohY0ZnxbJG2/MGBvbkhNn3MgpNuxt+5/cw/OwWXLOOQnDDTi08J3PMf74s80usX9G+sYHP9vSbHvYkw9+eFNmI4/LFoUDDGwSaGLwxIAdyDcwMH/AKTsKRsEoGAWjAAQAaOdhdoq0ZsEAAAAASUVORK5CYII=","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":true,"prefix":"","firstName":"Zhenchao","middleName":"","lastName":"Yang","suffix":""},{"id":399069812,"identity":"492a1ff3-50c5-4628-a96c-6dae8ea504af","order_by":5,"name":"Yongjun Wu","email":"","orcid":"","institution":"Northwest Agriculture and Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Yongjun","middleName":"","lastName":"Wu","suffix":""}],"badges":[],"createdAt":"2024-12-25 11:23:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5710860/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5710860/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-27542-4","type":"published","date":"2025-12-08T15:59:05+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":73309805,"identity":"b13e14f9-310b-413c-bd30-4c9706dbc93d","added_by":"auto","created_at":"2025-01-08 17:58:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":309920,"visible":true,"origin":"","legend":"\u003cp\u003eThe physicochemical properties of compost under various treatment conditions are shown. Figures a-d illustrate the changes in temperature, pH, electrical conductivity (EC), and germination index (GI) values during composting. Error bars represent the standard deviation of each data set.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/04e174e9da455df50d1cb410.png"},{"id":73309807,"identity":"fe9fb84a-3b5f-4346-bb8f-59cb3000fa1c","added_by":"auto","created_at":"2025-01-08 17:58:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":161929,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in nutrient content of compost under different treatment conditions. a-b represent the changes of ammonium nitrogen and nitrate nitrogen in the composting process, respectively. The error lines indicate the standard deviation of each data set.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/21cea00c91948eac773879b3.png"},{"id":73310160,"identity":"509891cb-621a-439d-b669-b80cf2966b2b","added_by":"auto","created_at":"2025-01-08 18:06:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":156143,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in nutrient content of compost under different treatment conditions. a-c represent the changes in humic acid, fulvic acid and organic matter under different treatment conditions of compost, respectively. Error lines indicate the standard deviation of each data set.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/52c6ee0254f578925b1629f8.png"},{"id":73309809,"identity":"18b47539-6005-488e-8a91-d850ded53e96","added_by":"auto","created_at":"2025-01-08 17:58:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":155486,"visible":true,"origin":"","legend":"\u003cp\u003eVariation of lignocellulose content in different treatments. Figures (a-c) show the changes in cellulose, hemicellulose and lignin content, respectively. The error lines indicate the standard deviation of each data set.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/89158ba721892b1cde0b07e3.png"},{"id":73309812,"identity":"ab45d7dd-cbd5-434a-a189-41e6ea74a04b","added_by":"auto","created_at":"2025-01-08 17:58:32","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":752470,"visible":true,"origin":"","legend":"\u003cp\u003eSEM of compost material with different additives (a) represents SEM before composting and (b-f) represents SEM of CK, T1, T2, T3 and T4 after composting treatment.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/9a0485be99acc704e2620804.png"},{"id":73311145,"identity":"adef8de9-d7b2-494b-87ed-5f600f27131e","added_by":"auto","created_at":"2025-01-08 18:14:32","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":206364,"visible":true,"origin":"","legend":"\u003cp\u003eBacterial community succession and differences between treatments at phylum (a) and genus (b) levels during tomato straw composting.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/22bff31e872a8e51e15441be.png"},{"id":73309814,"identity":"feb0ceb4-39ee-4d49-b17d-581290bd8f5a","added_by":"auto","created_at":"2025-01-08 17:58:32","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":38758,"visible":true,"origin":"","legend":"\u003cp\u003eredundancy analysis (a) and mantel test (b).\u003c/p\u003e","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/93283cae567bd3cc3170af70.png"},{"id":98244004,"identity":"b2822d8f-c434-417e-a935-1f3887e267f9","added_by":"auto","created_at":"2025-12-15 16:12:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2932002,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5710860/v1/5303febe-03ee-4269-8a84-1e1c5fc81cf3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effects of different exogenous additives on humification and microbial community during tomato straw composting process","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAs societies develop and populations increase, the demand for agricultural development and yield improvement also rises \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Continuous agricultural development generates large amounts of organic waste, making its proper management a critical issue. Aerobic composting is the primary method for managing agricultural organic waste. Its products not only improve soil physical and chemical properties but also serve as a substitute for inorganic fertilizers, promoting agricultural production \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. It is widely recognized as an economical, environmentally friendly, and potentially sustainable method for treating various organic wastes\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHowever, the composting of agricultural organic waste faces several challenges, including long maturation cycles, nitrogen loss, and the production of unstable or immature compost. Immature compost contains lower nutrient levels, higher amounts of pathogenic bacteria and insect eggs, and can also be toxic to plants \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Humus is a critical indicator of compost maturity and plays a key role in the composting process \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Therefore, improving the quality of compost products and shortening the composting process are essential for achieving effective organic waste recycling.\u003c/p\u003e \u003cp\u003eHumus-rich compost plays a crucial role in soil conditioning and promoting plant growth \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. To accelerate the composting process and enhance humification, researchers have manipulated aeration \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e, inoculated with microbial agents, controlled turning frequency \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, applied hydrothermal pretreatment \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, and used mulch films \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, among other strategies. In practical composting, due to limited control over raw materials and process parameters, many researchers have added various additives to enhance organic matter decomposition and humification \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. These additives include calcium superphosphate\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, phosphogypsum\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, and biochar \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Wang et al. added 10% biochar to wine lees compost and found that it reduced nitrogen loss and accelerated microbial community succession, thus enhancing the composting process \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Lei et al. reported that adding 10% phosphogypsum to manure compost promoted microbial nitrogen conversion, significantly improved compost quality, and shortened the composting duration. Zhao et al. added 18% calcium superphosphate to chicken manure compost, finding that it effectively promoted ammonium and nitrate nitrogen accumulation and altered microbial nitrogen fixation strategies\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. However, these studies were limited to single comparisons and did not identify the optimal additives for enhancing the composting process and humification.\u003c/p\u003e \u003cp\u003eThis study aimed to investigate the effects of various additives on the physicochemical properties, degree of decomposition, and microbial community in tomato straw compost during the composting process. The objectives of this study were: (1) to assess the impact of additives on the physicochemical properties and decomposition degree of the compost; (2) to identify optimal additives for improving compost quality and accelerating the composting process; and (3) to explore the correlation between physicochemical properties and key microorganisms under different additives. The study's results can enhance the composting process and recycling of organic waste, providing valuable insights for future research.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Test materials and experimental design\u003c/h2\u003e \u003cp\u003eIn this experiment, tomato straw was collected from a greenhouse in Yangling, Shaanxi Province, China, and ground to a 100-mesh size after drying. The EM bacterial agent was supplied by Henan Henkun Animal Husbandry Science and Technology Co., containing over 80 types of microorganisms across 10 genera. Biochar, in the form of agricultural wheat straw biochar powder, was purchased from Goodwill Sino-Austria. Calcium superphosphate was purchased from Hebei Xianzheng Agricultural Science and Technology Co. Phosphogypsum, primarily composed of CaSO₄\u0026middot;2H₂O, was purchased from Suzhou Xinqing Technology Co.\u003c/p\u003e \u003cp\u003eFive treatments were designed for the experiment: T1 (straw\u0026thinsp;+\u0026thinsp;0.5% microbial agent), T2 (straw\u0026thinsp;+\u0026thinsp;10% biochar\u0026thinsp;+\u0026thinsp;0.5% microbial agent), T3 (straw\u0026thinsp;+\u0026thinsp;10% calcium superphosphate\u0026thinsp;+\u0026thinsp;0.5% microbial agent), T4 (straw\u0026thinsp;+\u0026thinsp;10% phosphogypsum\u0026thinsp;+\u0026thinsp;0.5% microbial agent), and CK (blank control group with no treatments). All additives were added based on the dry weight percentage of the initial raw material. The experiment used a 300L homemade forced-ventilated static reactor for aerobic fermentation. The water content of the pile was adjusted to 60% using distilled water. Intermittent aeration was applied: 10 minutes of aeration followed by 50 minutes of cessation, with an aeration rate of 0.3 L/(L\u0026middot;min). The compost was turned at various stages during the composting process. Compost samples (approximately 200 g, fresh weight) were collected and divided into two portions. One portion was used for physicochemical parameters, elemental analysis, and lignocellulosic material determination, while the other portion was used for microbial analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Determination of physical and chemical properties\u003c/h2\u003e \u003cp\u003eDigital temperature sensors (Shenzhen Shenghuaxuan Technology Co., Ltd., Shenzhen, China) were installed at three positions (top, middle, and bottom) of the homemade compost tank, and ambient temperature was recorded simultaneously. Both compost and ambient temperatures were measured using an MT-8X multi-channel temperature recorder (Shenzhen Shenghuaxuan Technology Co., Ltd., China). The average temperatures at 9:00 a.m., 2:00 p.m., and 7:00 p.m. were recorded as the daily temperatures.\u003c/p\u003e \u003cp\u003eThe samples were dried at 105\u0026deg;C for 24 hours to determine the water content \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. The sample weight was determined by first placing an empty aluminum box in an oven at 105\u0026deg;C until dry, then adding a known amount of sample to the box to measure the initial weight, and drying the sample in the oven at 105\u0026deg;C for 12 hours before recording the final weight after cooling. Moisture content was calculated based on the initial and final weights.\u003c/p\u003e \u003cp\u003epH and electrical conductivity (EC) values were measured using a pH meter and an EC meter (Shanghai Inian Precision Instruments Co., Ltd.), with a 1:10 (w/v, sample: water) ratio for fresh samples. The samples (DW) were mixed with distilled water at a 1:10 (w/v) ratio and shaken in a thermostatic oscillator at 120 rpm for 1 hour. After filtering the samples through filter paper, pH and EC values were measured using a pH meter (OHAUS ST10) and an EC meter (OHAUS ST20), both made in China. A seed germination test was performed using the aqueous extract prepared as described. Five milliliters of supernatant were placed in a glass container with filter paper, and 20 cabbage seeds were evenly distributed. The seeds were incubated in the dark at 25\u0026deg;C for 48 hours. Distilled water was used as a control, and the seed germination index (GI) was calculated according to the following formula:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:\\text{G}\\text{I}\\left(\\text{%}\\right)=\\frac{\\text{G}\\text{e}\\text{r}\\text{m}\\text{i}\\text{n}\\text{a}\\text{t}\\text{i}\\text{o}\\text{n}\\:\\text{r}\\text{a}\\text{t}\\text{e}\\:\\text{o}\\text{f}\\:\\text{t}\\text{r}\\text{e}\\text{a}\\text{t}\\text{e}\\text{d}\\:\\text{s}\\text{e}\\text{e}\\text{d}\\text{s}\\:\\left(\\text{%}\\right)\\times\\:\\text{S}\\text{e}\\text{e}\\text{d}\\:\\text{r}\\text{o}\\text{o}\\text{t}\\:\\text{l}\\text{e}\\text{n}\\text{g}\\text{t}\\text{h}}{\\:\\text{G}\\text{e}\\text{r}\\text{m}\\text{i}\\text{n}\\text{a}\\text{t}\\text{i}\\text{o}\\text{n}\\:\\text{r}\\text{a}\\text{t}\\text{e}\\:\\:\\text{o}\\text{f}\\:\\text{c}\\text{o}\\text{n}\\text{t}\\text{r}\\text{o}\\text{l}\\:\\text{s}\\text{e}\\text{e}\\text{d}\\text{s}\\:\\left(\\text{%}\\right)\\times\\:\\text{S}\\text{e}\\text{e}\\text{d}\\:\\text{r}\\text{o}\\text{o}\\text{t}\\:\\text{l}\\text{e}\\text{n}\\text{g}\\text{t}\\text{h}}\\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eNH₄⁺-N was determined using the colorimetric method, and NO₃⁻-N was determined using the spectrophotometric method \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Organic matter was quantified by burning the samples at 550\u0026deg;C for 8 hours \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. The absorbance of FA and HA components was measured at 465 nm and 665 nm using a UV-Vis spectrophotometer (WFH-201B, Shanghai Intan Precision Instrument Co., Ltd.)\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Cellulose, hemicellulose, and lignin content were determined according to the method described by Sajid et al \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Cellulose content was determined using the Van\u0026rsquo;s detergent method.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Scanning electron microscope analysis before and after straw degradation\u003c/h2\u003e \u003cp\u003eThe samples were cleaned with distilled water, air-dried, and subsequently observed under a scanning electron microscope (Hitachi, Japan, S-3400 N) to identify any changes. To ensure proper fixation, the samples were mounted under vacuum using double-sided conductive tape and coated with a thin layer of gold \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Finally, the samples were observed and analyzed at an accelerating voltage of 10 kV and a filament current of 2.7 A.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 DNA extraction and sequencing analysis\u003c/h2\u003e \u003cp\u003eSamples were collected on days 0, 5, 19, 40, and 65 of composting. The microbial community diversity was characterized using high-throughput sequencing, and genomic DNA was extracted from 0.5 g of compost using the E.Z.N.A. Stool DNA Kit (D4015, Omega Inc., USA). DNA was extracted by 1% agarose gel electrophoresis and quantified using a NanoDrop\u0026trade; 2000 Spectrophotometer. PCR amplification was conducted with universal bacterial primers 338F: 5\u0026acute;-ACTCCTACGGGGAGGCAGCA-3\u0026acute; and 806R: 5\u0026acute;-GGACTACHVGGGGTWTCTAAT-3\u0026acute;, as well as fungal primers ITS1F: 5\u0026acute;-CTTGGTCATTTAGAGGAAGTAA-3\u0026acute; and ITS2: 5\u0026acute;-GCTGCGTTCTTCATCGATGC-3\u0026acute;. PCR products were purified with AMPure XT (Beckman Coulter Genomics, Danvers, MA, USA) and quantified using a Qubit (Invitrogen, Waltham, MA, USA) according to the method described by Li et al. The purified PCR products were evaluated using an Agilent 2100 Bioanalyzer (USA) and an Illumina library quantification kit (Kapa Biosciences, Woburn, MA, USA) to assess the size and quantity of the amplified libraries. Identification and sequencing were carried out on the NovaSeq PE250 platform (LC-Bio Technology Co., Ltd., Hangzhou, China).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Statistical analysis\u003c/h2\u003e \u003cp\u003eData from the composting experiment were analyzed using SPSS 26.0 (IBM, USA) to calculate the mean and standard deviation for each treatment. A one-way analysis of variance (ANOVA) was performed to assess differences between treatments, with statistical significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Data were visualized and plotted using Origin 2018 (OriginLab Corp., USA).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Effect of different additives on the physical and chemical properties of the heap\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1 Temperature\u003c/h2\u003e \u003cp\u003eTemperature is a key indicator in the composting of agricultural organic waste, reflecting the degradation efficiency of organic matter and the extent of pile decomposition\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. Based on temperature changes, the composting process can be divided into four stages: warming, high temperature, cooling, and putrefaction\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, the temperature change trend in all treatments is consistent: the temperature rises rapidly to a peak and then gradually decreases. The rapid temperature increase at the beginning of composting is primarily due to the metabolism and reproduction of aerobic microorganisms, which consume easily degradable organic matter and release substantial energy \u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. The high temperature stage (\u0026gt;\u0026thinsp;55\u0026deg;C) lasted for 11 days (CK), 17 days (T1), 15 days (T2), 15 days (T3), and 15 days (T4) for each treatment, meeting the composting requirement of maintaining temperatures above 55\u0026deg;C for over 7 days\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. As the temperature rises, microbial activity in the heap is inhibited, the decomposition rate of organic waste decreases, and the heap temperature begins to drop. Once easily degradable substances in the heap are exhausted through microbial decomposition, the temperature approaches ambient levels, indicating the completion of composting\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. The temperature of the pile with the additive was slightly higher than that of the CK treatment, but the difference was not statistically significant.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e3.1.2 pH\u003c/h2\u003e \u003cp\u003eThe pH trends were similar across all treatments during the composting process (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). In the early stages of composting, pH increased due to the decomposition of organic matter, ammonification of organic nitrogen, and the formation and dissolution of ammonia\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. The pH values for all treatments peaked on day 11 at 8.64 (CK), 8.65 (T1), 8.90 (T2), 8.46 (T3), and 8.55 (T4), consistent with the findings of Pan et al. (2018). Between days 11 and 14, the organic acids produced by microbial reactions \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e, along with the volatilization and humification of NH₃ \u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e, caused a decrease in pH for all treatments. Subsequent pH increases were due to the degradation of organic acids or proteins and nitrification\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. At the end of composting, the pH values of the treatments were 9.11 (CK), 9.02 (T1), 9.20 (T2), 8.74 (T3), and 8.88 (T4), respectively. The relatively high pH in the T2 treatment was primarily due to the alkaline nature of the added biochar, which has higher porosity and specific surface area, facilitating ammonia uptake and raising the pH.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e3.1.3 EC\u003c/h2\u003e \u003cp\u003eThis study investigates the potential effects of electrical conductivity (EC) on salinity content in compost substrates, as well as its impact on seed germination and plant growth\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, at the beginning of composting, as the pile temperature increases, microorganisms consume a large amount of nutrients in ionic form, leading to a decrease in EC \u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. On day 8, the EC values reached their lowest levels in CK (3.92 mS/cm), T1 (3.96 mS/cm), T2 (4.10 mS/cm), T3 (4.25 mS/cm), and T4 (4.24 mS/cm). As composting progresses, the microbial decomposition of the pile releases large amounts of soluble salts \u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e, causing a gradual increase in EC. From day 48 onwards, the volatilization of small molecules and the complexation reactions during humification stabilized the final EC of the heap\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. Eventually, the EC values reached a steady state at 5.10 mS/cm for CK, 5.14 mS/cm for T1, 4.90 mS/cm for T2, 5.62 mS/cm for T3, and 5.23 mS/cm for T4. At the beginning of composting, EC values differed between treatments due to variations in the nature of the additives (p\u0026amp;lt;0.05). At the end of composting, the T2 treatment exhibited the lowest EC, primarily due to the strong adsorption capacity of biochar on ions, which reduced the concentration of soluble salts \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Higher EC values in the T3 and T4 treatments were attributed to an increase in SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, and PO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3-\u003c/sup\u003e ions due to the addition of additives\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e, leading to an elevated EC.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e3.1.4 GI\u003c/h2\u003e \u003cp\u003eThe germination index (GI) is primarily used to assess the biotoxicity and maturity of compost. It increases as toxic substances decompose during the composting process \u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. At the start of composting, the GI of all treatments remained low (\u0026lt;\u0026thinsp;50%)(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). By day 26, GI values increased and reached 80% in all treatments, except for CK (75.11%), indicating that the compost had matured and was no longer phytotoxic\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. During the first 26 days of composting, GI values increased rapidly in all treatments. This increase may be attributed to the biodegradation of phytotoxic substances (e.g., volatile fatty acids and ammonium) and the accumulation of humus\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. By the end of composting, the GI of each treatment reached its maximum value: 98.45% for CK, 105.65% for T1, 121.26% for T2, 110.48% for T3, and 115.57% for T4. The differences in GI values between treatments reflected variations in compost quality.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Effect of different additives on nitrogen, organic matter, HA and FA in the heap\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.2.1 Ammonium nitrogen\u003c/h2\u003e \u003cp\u003eThe NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N content increased rapidly in all treatments at the beginning of composting, peaking on day 14 with values of 3800.04 mg/kg for CK, 3527.59 mg/kg for T1, 2473.38 mg/kg for T2, 2919.77 mg/kg for T3, and 2785.34 mg/kg for T4 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). This increase is primarily due to the degradation of organic matter by microorganisms early in the composting process, coupled with increased ammonification and the inhibition of nitrification at high temperatures. These factors promote NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e production and NH\u003csub\u003e3\u003c/sub\u003e volatilization in the compost heap \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N content gradually decreased during composting and reached its lowest value at the end of the process: 1146.94 mg/kg in CK, 1375.97 mg/kg in T1, 791.85 mg/kg in T2, 926.70 mg/kg in T3, and 949.88 mg/kg in T4. The NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N content continued to decrease, likely due to ammonification leading to NH\u003csub\u003e3\u003c/sub\u003e volatilization, as well as increased microbial nitrification and nitrogen fixation\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. By the end of composting, NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N levels remained higher in CK (1146.94 mg/kg) and T1 (1375.97 mg/kg) than in the other treatments. The decrease in NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N content during the late stage of composting may be due to two factors: (1) Excess nitrogen is released as NH\u003csub\u003e3\u003c/sub\u003e (NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e \u0026rarr; NH\u003csub\u003e3\u003c/sub\u003e\u0026uarr; + H\u003csup\u003e+\u003c/sup\u003e), and (2) Nitrification by nitrifying bacteria: NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e + 2O\u003csub\u003e2\u003c/sub\u003e \u0026rarr; NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e + H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;2H\u003csup\u003e+\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.2.2 Nitrate nitrogen\u003c/h2\u003e \u003cp\u003eNitrate is crucial for agricultural production as it serves as the primary source of nitrogen for most plants\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. During the initial phase of composting, the NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N content in all treatments remained stable (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). However, as composting progressed, the NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N content increased in all treatments, reaching higher levels at the end: CK (16717.32 mg/kg), T1 (1730.59 mg/kg), T2 (1936.08 mg/kg), T3 (1796.03 mg/kg), and T4 (1827.55 mg/kg). The lack of significant change in NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N at the beginning of composting may be attributed to high ammonia levels and elevated temperatures, which inhibit nitrifying bacteria activity \u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. This effect persisted until day 26. As the temperature of the compost pile decreased, nitrifying bacteria became active again, promoting nitrification (Xu et al., 2024). This facilitated the conversion of NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N to NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N, leading to a significant increase in NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N content (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). At the end of composting, T2 treatment exhibited the highest NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e-N content, suggesting that biochar may create a microenvironment that enhances the nitrification process\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.2.3 Humic acid\u003c/h2\u003e \u003cp\u003eThe main component of humus is humic acid (HA), which reduces phytotoxicity and enhances compost quality. The HA content gradually increased throughout the composting process \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, the HA content in the compost pile increased by 83.54% (CK), 106.18% (T1), 127.01% (T2), 122.60% (T3), and 111.61% (T4) by the end of composting. The HA content was higher in the T2, T3, and T4 treatments. This suggests that the addition of biochar, exogenous microorganisms, and calcium superphosphate promotes HA formation during composting \u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.2.4 Fulvic acid\u003c/h2\u003e \u003cp\u003eThe decrease in FA and soluble organic carbon content is attributed to microbial degradation during the composting process \u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. In comparison with HA, FA content gradually decreased across all treatments throughout the composting process. Notably, the most rapid decrease occurred during the first 0\u0026ndash;8 days of composting (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The T2 treatment exhibited the largest decrease in FA (64.25%), followed by T1 (51.08%), T4 (50.65%), CK (46.71%), and T3 (43.76%). The rapid decline in FA during the early stage of composting is primarily due to microorganisms utilizing readily available organic matter (i.e., FA) as an energy source \u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. Additionally, unstable humus components (FA) can be converted into stable components (HA)\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. The gradual decrease in FA indicates a reduction in readily available organic carbon, leading to increased compost stability. By the end of the composting process, the FA content stabilized at low levels: 7.86 g/kg (CK), 7.81 g/kg (T1), 3.62 g/kg (T2), 7.50 g/kg (T3), and 4.47 g/kg (T4).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.2.5 Organic matter\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec shows the changes in organic matter across the five treatments during the composting process. The highest OM content was observed in the initial feedstock, after which it decreased in all treatments. The decline was rapid during the first 8 days of composting, followed by a slowdown. By the end of composting, OM degradation percentages were 39%, 41%, 63%, 53%, and 58% in CK, T1, T2, T3, and T4, respectively. A positive feedback relationship between OM degradation and composting temperature was observed, which was linked to microbial activity \u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e. T2, T3, and T4 exhibited higher and longer temperature increases and thermophilic periods compared to CK and T1. This suggests that biochar, phosphogypsum, and superphosphate enhanced microbial activity, accelerated OM consumption, and promoted compost maturation. T2 exhibited the highest maturation and OM degradation in the final compost, indicating that microbial activity in T2 was higher than in the other treatments.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Effect of different treatments on the change of lignocellulose content in the heaps\u003c/h2\u003e \u003cp\u003eThe cellulose content in each treatment followed a similar trend, with a rapid decrease at the beginning, followed by a gradual slowdown in degradation as composting progressed. This may be attributed to higher temperatures in the early stages, which enhanced microbial activity, promoting cellulose degradation and accelerating the overall degradation rate \u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe cellulose content decreased gradually in all treatments. At the end of composting, the relative cellulose content was 14.35% (CK), 13.89% (T1), 10.85% (T2), 12.25% (T3), and 11.66% (T4). The degradation rates at the end of composting were CK (62.61%), T1 (59.34%), T2 (69.82%), T3 (69.10%), and T4 (68.76%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003eThe changes in hemicellulose content across all treatments are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb. The hemicellulose content in all treatments continuously decreased during composting and stabilized by the end. These results are consistent with those of Wang et al \u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e, who composted a mixture of maitake and pig manure. In their study, microorganisms utilized hemicellulose as a carbon source, leading to a reduction in hemicellulose content \u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. In this study, the rate of hemicellulose degradation was faster in all treatments during the first 0\u0026ndash;19 days of composting. The degradation during this period accounted for 51.6\u0026ndash;68.9% of the total hemicellulose loss. This may be due to higher temperatures and increased microbial activity, which accelerated the decomposition of hemicellulose \u003csup\u003e\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. At the end of composting, the hemicellulose content was 2.93% (CK), 3.02% (T1), 1.84% (T2), 2.19% (T3), and 2.03% (T4).\u003c/p\u003e \u003cp\u003eLignin is resistant to degradation due to its insoluble, irregular, and highly branched structure\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e. Its degradation products are precursors for the formation of humic substances (HS)\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. The initial relative lignin content was similar across all treatments and increased rapidly during composting, peaking at 16.02% (CK), 16.39% (T1), 18.67% (T2), 17.86% (T3), and 16.93% (T4) on day 40 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). The increase in lignin content in all treatments can be attributed to the more rapid degradation of readily available organic matter (e.g., soluble sugars, proteins, hemicellulose, and cellulose) compared to lignin, resulting in the accumulation of lignin\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e,\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e. The lignin content then decreased, and at the end of composting, the relative lignin content in T2 was 16.09% higher than that in CK (13.27%), T1 (14.52%), T3 (15.33%), and T4 (15.97%).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Analysis of the effect of different treatments on the effectiveness of tomato straw composting\u003c/h2\u003e \u003cp\u003eThe tomato straw composting process was completed after 65 days. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the maturation indices for each treatment at the end of composting. The key indices include pH, EC, NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N, NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e-N, humic acid, fulvic acid, organic matter, hemicellulose content, cellulose content, and lignin content. The data indicated that exogenous additives extended the high-temperature phase of composting and increased the degree of decomposition by the end. Biochar had the most significant effect. The biochar addition treatment (T2) significantly increased the humic acid content by 127.01% and enhanced the degradation rates of organic matter and cellulose to 63% and 69.82%, respectively, outperforming the control group.\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\u003eSelected compost maturity parameters at the end of composting.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\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\" colname=\"c2\"\u003e \u003cp\u003eCK\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eT2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eT3\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eT4\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e9.112\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e9.195\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e8.743\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e8.876\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEC(mS/cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e4.90\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e5.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e5.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGI (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e98.45\u0026thinsp;\u0026plusmn;\u0026thinsp;2.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e105.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e121.26\u0026thinsp;\u0026plusmn;\u0026thinsp;8.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e110.48\u0026thinsp;\u0026plusmn;\u0026thinsp;4.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e115.57\u0026thinsp;\u0026plusmn;\u0026thinsp;2.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N (mg/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1146.94\u0026thinsp;\u0026plusmn;\u0026thinsp;12.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1375.97\u0026thinsp;\u0026plusmn;\u0026thinsp;25.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e791.85\u0026thinsp;\u0026plusmn;\u0026thinsp;10.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e926.7\u0026thinsp;\u0026plusmn;\u0026thinsp;25.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e949.88\u0026thinsp;\u0026plusmn;\u0026thinsp;39.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e-N (mg/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1617.32\u0026thinsp;\u0026plusmn;\u0026thinsp;49.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1730.23\u0026thinsp;\u0026plusmn;\u0026thinsp;23.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1936.08\u0026thinsp;\u0026plusmn;\u0026thinsp;36.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e1796.03\u0026thinsp;\u0026plusmn;\u0026thinsp;42.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e1827.55\u0026thinsp;\u0026plusmn;\u0026thinsp;29.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHumic-acid\u003c/p\u003e \u003cp\u003e(g/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e21.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e23.69\u0026thinsp;\u0026plusmn;\u0026thinsp;1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e28.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e26.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e25.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFulvic-acid\u003c/p\u003e \u003cp\u003e(g/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e7.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e4.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOM (g/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e326.77\u0026thinsp;\u0026plusmn;\u0026thinsp;2.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e316.63\u0026thinsp;\u0026plusmn;\u0026thinsp;14.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e197.41\u0026thinsp;\u0026plusmn;\u0026thinsp;20.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e247.70\u0026thinsp;\u0026plusmn;\u0026thinsp;14.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e229.28\u0026thinsp;\u0026plusmn;\u0026thinsp;11.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemicellulose\u003c/p\u003e \u003cp\u003econtent (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.02\u0026thinsp;\u0026plusmn;\u0026thinsp;1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.84\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e2.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e2.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.63\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose\u003c/p\u003e \u003cp\u003econtent (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e14.35\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e13.90\u0026thinsp;\u0026plusmn;\u0026thinsp;1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e10.85\u0026thinsp;\u0026plusmn;\u0026thinsp;3.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e12.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e11.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLignin\u003c/p\u003e \u003cp\u003econtent (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e13.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e14.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e16.09\u0026thinsp;\u0026plusmn;\u0026thinsp;1.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e15.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e15.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eT1: straw\u0026thinsp;+\u0026thinsp;0.5% microbial agent; T2: straw\u0026thinsp;+\u0026thinsp;10% biochar\u0026thinsp;+\u0026thinsp;0.5% microbial agent; T3: straw\u0026thinsp;+\u0026thinsp;10% calcium superphosphate\u0026thinsp;+\u0026thinsp;0.5% microbial agent; T4: straw\u0026thinsp;+\u0026thinsp;10% phosphogypsum\u0026thinsp;+\u0026thinsp;0.5% microbial agent; CK: blank control group without treatment. Results are the mean of three replicates\u0026thinsp;+\u0026thinsp;standard deviation. (EC: Electrical conductivity, NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N: Ammonium nitrogen, NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e-N: Nitrate nitrogen; OM: Organic matter)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Effect of different additives on the microstructure of the stack material\u003c/h2\u003e \u003cp\u003eScanning electron microscopy observations revealed that the degree of decomposition on the surface of tomato straw varied across treatments. The surface of straw without composting treatment was smoother and more organized than that of the composted straw (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). After composting, the straw surface became rough, and the original lignocellulose structure was damaged, resulting in an uneven, partially broken, porous, and loose appearance \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb-f). In contrast, biochar-treated tomato straw exhibited larger surface voids and a rougher surface with debris. This is due to biochar's large surface area and porous nature, which improve the composting environment and provide physical support for microbial growth, thereby enhancing organic matter degradation and humification \u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e. These changes contribute to the thorough decomposition of the straw. Scanning electron microscopy observations further revealed that composting treatments with different additives were more favorable for the humification of tomato straw.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Changes in microbial communities during the composting process\u003c/h2\u003e \u003cdiv id=\"Sec24\" class=\"Section3\"\u003e \u003ch2\u003e3.6.1 Bacterial diversity\u003c/h2\u003e \u003cp\u003eThe composting process of tomato straw is significantly influenced by differences between treatments. The relative abundance of relevant microorganisms, which drive the degradation of agricultural organic wastes during composting, exhibited dynamic changes throughout the process. To assess the effect of exogenous additives on the microbial community during tomato straw composting, the relative abundance was analyzed at the bacterial phylum and genus levels.\u003c/p\u003e \u003cp\u003eThe relative abundance of bacterial phyla across different treatments is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. The top 10 bacterial phyla with the highest relative abundance include \u003cem\u003eFirmicutes\u003c/em\u003e (75.47%-79.5%), \u003cem\u003eActinobacteriota\u003c/em\u003e (13.37%-16.27%), \u003cem\u003eProteobacteria\u003c/em\u003e (4.58%-6.80%), \u003cem\u003ePlanctomycetota\u003c/em\u003e (0.02%-0.41%), Gemmatimonadota (0.06%-0.15%), \u003cem\u003ePatescibacteria\u003c/em\u003e (0.01%-0.05%), \u003cem\u003eBacteroidota\u003c/em\u003e (0.12%-0.77%), \u003cem\u003eVerrucomicrobiota\u003c/em\u003e (0.16%-0.32%), \u003cem\u003eMyxococcota\u003c/em\u003e (0.02%-0.1%), and \u003cem\u003eChloroflexi\u003c/em\u003e (0.01%-0.12%), which together account for more than 98% of the total bacterial phyla. \u003cem\u003eFirmicutes\u003c/em\u003e not only exhibit high lignocellulose degradation capacity but also demonstrate strong tolerance to adverse conditions during composting, which enhances the degradation of tomato straw\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. However, by the end of the composting process, the relative abundance of \u003cem\u003eFirmicutes\u003c/em\u003e across treatments decreased to 9.81%-20.84%. A similar result was reported byWang et al., (2022), and Peng et al. (2021)\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e also found similar results when zeolite and calcium superphosphate were used as additives in the pig manure composting process.In the mature compost samples, \u003cem\u003eBacteroidota\u003c/em\u003e (1.37%-5.37%) was identified as a major phylum, with the ability to break down cellulose, hemicellulose, and lignin\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e. \u003cem\u003eProteobacteria\u003c/em\u003e primarily contribute to carbon cycling and the mineralization of nitrogenous organic matter during composting\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e. In the early stages, they degrade proteins and starch, and as composting progresses, both \u003cem\u003eProteobacteria\u003c/em\u003e and \u003cem\u003eActinobacteriota\u003c/em\u003e increase in abundance (10.79%-15.64%) and begin to decompose cellulose, likely due to their ability to degrade other organic matter and their thermophilic nature\u003csup\u003e\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e\u003c/sup\u003e. \u003cem\u003eActinobacteriota\u003c/em\u003e, which is known for its strong cellulose and lignin degradation capabilities, plays a significant role in compost maturation and humification, with its relative abundance closely correlated to temperature changes in the compost pile\u003csup\u003e\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. It is commonly used as an indicator of compost maturity. Gemmatimonadota also aids in cellulose and protein hydrolysis during composting \u003csup\u003e\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e\u003c/sup\u003e. The dominant phyla in the composting process exhibit variations due to the influence of exogenous additives or environmental factors, which in turn affect the overall maturity of the compost.\u003c/p\u003e \u003cp\u003eSignificant differences in microbial composition at the genus level can be observed both between treatments and between different time points within the same treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). The top 10 genera by relative abundance across the six treatments were \u003cem\u003eBacillus\u003c/em\u003e, \u003cem\u003eWeissella\u003c/em\u003e, \u003cem\u003eCorynebacterium\u003c/em\u003e, \u003cem\u003eStaphylococcus\u003c/em\u003e, \u003cem\u003eHalocella\u003c/em\u003e, \u003cem\u003eS0134_terrestrial_group_unclassified\u003c/em\u003e, \u003cem\u003eBacillales_unclassified\u003c/em\u003e, \u003cem\u003eBacillaceae_unclassified\u003c/em\u003e, \u003cem\u003ePlanctomycetales_unclassified\u003c/em\u003e, and \u003cem\u003eSinibacillus\u003c/em\u003e. \u003cem\u003eBacillus\u003c/em\u003e exhibited the highest relative abundance across all treatments. The relative abundance of \u003cem\u003eBacillus\u003c/em\u003e was initially low at the start of the composting process (0.5\u0026ndash;1.02%) but gradually increased during composting (18.59\u0026ndash;37.88%). It became the dominant genus in the high-temperature stage and significantly contributed to lignocellulose degradation. The relative abundance of \u003cem\u003eBacillus\u003c/em\u003e gradually decreased as composting progressed, likely due to the reduction of available nutrients. \u003cem\u003eBacillus\u003c/em\u003e may also utilize degradation byproducts to promote the formation of humic acid and xanthate organic compounds in the compost \u003csup\u003e\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e. \u003cem\u003eWeissella\u003c/em\u003e (25.13\u0026ndash;35.80%) and \u003cem\u003eStaphylococcus\u003c/em\u003e (20.00-28.32%) dominated the compost warming phase. \u003cem\u003eStaphylococcus\u003c/em\u003e played a key role in transforming the humus fraction, thereby increasing the accumulation of AK content (Xu et al., 2024). \u003cem\u003eHalocella\u003c/em\u003e is a mesophilic bacterium with low relative abundance during the warming and high-temperature phases of composting. Its abundance increases as temperature decreases, and it primarily degrades tough materials such as cellulose\u003csup\u003e\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e3.6.2 Redundancy analysis (RDA)\u003c/h2\u003e \u003cp\u003eTemperature changes in the bacterial community were primarily positively correlated with \u003cem\u003eWeissella\u003c/em\u003e and \u003cem\u003eStaphylococcus\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea). This indicates that these two microorganisms play a role in promoting the composting temperature, which may be related to their strong degradation of organic matter.These microorganisms were also positively correlated with NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N, cellulose, hemicellulose, organic matter (OM), and fatty acids (FA). pH, electrical conductivity (EC), and germination index (GI) were positively correlated with \u003cem\u003eCorynebacterium\u003c/em\u003e, \u003cem\u003eS0134_terrestrial_group_unclassified\u003c/em\u003e, \u003cem\u003eBacillus\u003c/em\u003e, \u003cem\u003ePlanctomycetales_unclassified\u003c/em\u003e, and \u003cem\u003eHalocella\u003c/em\u003e, indicating that these microorganisms play a role in promoting compost maturation. Nitrate (NO3\u0026ndash;N), humic acids (HA), and lignin were positively correlated with \u003cem\u003eCorynebacterium\u003c/em\u003e, \u003cem\u003eS0134_terrestrial_group_unclassified\u003c/em\u003e, \u003cem\u003eBacillus\u003c/em\u003e (unclassified), \u003cem\u003ePlanctomycetales_unclassified\u003c/em\u003e, and \u003cem\u003eHalocella\u003c/em\u003e. The correlation between key microorganisms in the composting process and indicators of compost decay and maturation can be further examined using RDA. This further supports the role of microorganisms in promoting compost decay and maturation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003e3.6.3 Mental analysis\u003c/h2\u003e \u003cp\u003eThe maturity and humification of compost are influenced not only by its physicochemical properties but also by the associated microbial communities. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb presents the Mantel test results of compost physicochemical properties and key microorganisms on the maturity and humification during tomato straw composting. The germination index (GI) and hemicellulose in tomato straw compost showed a significant positive correlation (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), indicating that hemicellulose plays a key role in reducing compost toxicity during composting. Humic acid (HA) was positively correlated with NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e-N, organic matter (OM), hemicellulose, and \u003cem\u003eCorynebacterium\u003c/em\u003e (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This suggests that the decrease in nitrate nitrogen and OM content during composting reflects the degree of humification, while the positive correlation between hemicellulose, \u003cem\u003eCorynebacterium\u003c/em\u003e, and organic acids (OA) indicates their role in promoting HA formation. The key factors and microorganisms influencing the maturation and humification of tomato straw compost were further identified through the Mantel test.\u003c/p\u003e\u003c/div\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study examined the effects of exogenous additives\u0026mdash;biochar, phosphogypsum, and calcium superphosphate\u0026mdash;on microbial communities and humification during tomato straw composting. The results indicated that exogenous additives prolonged the high-temperature stage of composting and enhanced the degree of humification, with biochar having the most pronounced effect. The biochar addition treatment (T2) significantly increased the humic acid content by 127.01%, and enhanced the degradation rates of organic matter (63%) and cellulose (69.82%), outperforming the control. In microbial communities, \u003cem\u003eFirmicutes\u003c/em\u003e, \u003cem\u003eActinobacteriota\u003c/em\u003e, and \u003cem\u003eProteobacteria\u003c/em\u003e were the dominant phyla, playing key roles in lignocellulose degradation, and carbon and nitrogen cycling. Further RDA and Mantel test analysis revealed that \u003cem\u003eCorynebacterium\u003c/em\u003e was the key microorganism promoting compost humification and maturation. This study demonstrated the beneficial effect of biochar on tomato straw compost humification, providing a scientific basis for the resource utilization and sustainable development of agricultural organic waste.\u003c/p\u003e"},{"header":"Declarations","content":" \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eL.S.(Luolin Shu): Conceptualization, Methodology, Investigation, Writing \u0026ndash; original draft, Writing \u0026ndash; review \u0026amp; editing, and Data curation, Y.Y.(Yuanyuan Yang): Writing \u0026ndash; review \u0026amp; editing, X.Z. (Xue Zheng) and Q.C (Qi Chen): Formal analysis, Resources, Data curation, Y.Y.(Yuanyuan Yang): Writing \u0026ndash; review \u0026amp; editing, Y.W. (Yongjun Wu): Writing \u0026ndash; Review \u0026amp; Editing; Z.Y. (Zhenchao Yang): Conceptualization, Supervision, Project administration, and Funding acquisition. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data generated or analysed during this study are included in this published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eXu, P. et al. Microbial agents obtained from tomato straw composting effectively promote tomato straw compost maturation and improve compost quality. \u003cem\u003eEcotoxicol. Environ. Saf.\u003c/em\u003e \u003cb\u003e270\u003c/b\u003e, 115884 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJing et al. Mechanisms of soil N dynamics following long-term application of organic fertilizers to subtropical rain-fed purple soil in China. \u003cem\u003eSoil Biol. 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Effects of bacterial inoculation on lignocellulose degradation and microbial properties during cow dung composting. \u003cem\u003eBioengineered\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e, 2185945 .\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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"compost, exogenous additives, tomato straw, microbial community, humification","lastPublishedDoi":"10.21203/rs.3.rs-5710860/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5710860/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the effects of biochar, phosphogypsum, and calcium superphosphate on composting tomato straw to improve compost quality and reduce composting time. Four treatments were tested: T1 (tomato straw\u0026thinsp;+\u0026thinsp;0.5% EM bacterial agent), T2 (tomato straw\u0026thinsp;+\u0026thinsp;10% biochar\u0026thinsp;+\u0026thinsp;0.5% EM), T3 (tomato straw\u0026thinsp;+\u0026thinsp;10% superphosphate\u0026thinsp;+\u0026thinsp;0.5% EM), and T4 (tomato straw\u0026thinsp;+\u0026thinsp;10% phosphogypsum\u0026thinsp;+\u0026thinsp;0.5% EM). Results showed that these additives extended the high-temperature phase and improved compost maturity, with T2 being the most effective. T2 exhibited the highest increase in humic acid (127.01%) and the greatest degradation of organic matter (63%) and cellulose (69.82%), outperforming the control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Microbial analysis revealed that \u003cem\u003eFirmicutes\u003c/em\u003e, \u003cem\u003eActinobacteriota\u003c/em\u003e, and \u003cem\u003eProteobacteria\u003c/em\u003e dominated the phylum level, while Bacillus, Weissella, Staphylococcus, and \u003cem\u003eHalocella\u003c/em\u003e were key genera. \u003cem\u003eCorynebacterium\u003c/em\u003e was identified as the main microorganism responsible for spoilage and maturation. This study highlights biochar\u0026rsquo;s role in enhancing humification in tomato straw composting.\u003c/p\u003e","manuscriptTitle":"Effects of different exogenous additives on humification and microbial community during tomato straw composting process","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-08 17:58:27","doi":"10.21203/rs.3.rs-5710860/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-12T05:26:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-09T18:53:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"85451342511345623435984205881032274280","date":"2025-04-28T20:38:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"86321035596409712208905043226285138496","date":"2025-04-26T16:02:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-13T16:51:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"35422870120230873340938342290810826902","date":"2025-01-30T13:10:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53417883262419086872839850712174390595","date":"2025-01-30T04:24:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-29T14:12:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-29T13:59:51+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-01-07T19:54:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-06T11:33:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2024-12-25T11:16:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f6c29af8-1cf4-4dcd-a628-c73f105b7c82","owner":[],"postedDate":"January 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":42520465,"name":"Earth and environmental sciences/Environmental sciences"},{"id":42520466,"name":"Earth and environmental sciences/Ecology/Agri ecology"}],"tags":[],"updatedAt":"2025-12-15T16:04:53+00:00","versionOfRecord":{"articleIdentity":"rs-5710860","link":"https://doi.org/10.1038/s41598-025-27542-4","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-12-08 15:59:05","publishedOnDateReadable":"December 8th, 2025"},"versionCreatedAt":"2025-01-08 17:58:27","video":"","vorDoi":"10.1038/s41598-025-27542-4","vorDoiUrl":"https://doi.org/10.1038/s41598-025-27542-4","workflowStages":[]},"version":"v1","identity":"rs-5710860","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5710860","identity":"rs-5710860","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}