Response of biochar-amended clayey soils to water infiltration

Response of biochar-amended clayey soils to water infiltration | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Response of biochar-amended clayey soils to water infiltration Juan Li, Jianglong Shen, Shenglan Ye This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3981210/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Biochar is an effective clayey raw soils improver. The difference of the amount of biochar added will cause the difference of soil water infiltration. The effects of mass addition ratios of five types of biochar (B0, B5, B10, B15 and B20) on the migration distance of soil wet front, cumulative infiltration and water holding capacity were studied through laboratory soil column simulation experiments. The soil water infiltration process was simulated as well with R 2 of 0.992, using Philip model, Horton model and Kostiakov model, respectively. The results demonstrate that the initial infiltration rate, stable infiltration rate and cumulative infiltration volume decrease with the increase of biochar addition and provide a reference of biochar utilization to improve soil hydraulic properties and moisture infiltration performance of clayey raw soils. Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Environmental social sciences biochar soil moisture infiltration model clayey soils Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction The arid and semi-arid region in northwest China is an important grain producing area in China. For a long time, there exist some problems such as uneven seasonal distribution of rainfall, low utilization efficiency of irrigation water and great loss of soil evaporation. Therefore, it is of great significance to regulate field water condition reasonably and improve soil water holding capacity.[ 1 – 4 ]. Raw soil in general shows low fertility level, hard or too loose soil, soil water infiltration rate is small, unable to plant crops for effective water supply and nutrition supplement. [ 5 , 6 ]. Under natural conditions, the maturation process of raw soil is slow, making it difficult to meet the expectations of cultivators and the needs of agricultural development[ 7 ]. Through time verification, it is found that biochar soil amendments can improve the quality of newly cultivated land and wasteland rapidly, which is an effective soil restoration method with minimum sacrifice[ 8 – 13 ]. Infiltration is an important cyclic process of water in farmland soil, and the infiltration process determines the effective degree of soil acceptance of rainfall and irrigation water, and also affects surface runoff and soil water erosion processes[ 14 ]. Take effective measures to improve soil infiltration characteristics is an effective way to improve the soil's ability to store water and retain moisture and promote stable and high yields[ 15 – 22 ]. Different soil textures have a significant impact on soil moisture infiltration capacity [ 23 ]. Afrin et al. analyzed and discussed the soil texture on the ability of water infiltration in farmland soil based on the infiltration test data of field soil water accumulation under different soil texture conditions, and found that the infiltration rate of soil steadily decreases and the infiltration capacity decreases when the soil texture changes from light to heavy[ 24 ]. The greater the clay particle content of the soil, the smaller the cumulative infiltration volume of the soil in the same infiltration time, i.e., the more viscous and heavy the soil is, the worse its infiltration capacity[ 25 , 26 ]. For raw soils with relatively clayey texture and compact soil, the lack of agglomeration and low infiltration rate affects the acceptance of precipitation and irrigation water, and easily generates surface runoff, resulting in degradation of raw soil quality[ 27 , 30 ]. Therefore, how to improve its water storage capacity is the key to improve the quality of clayey raw soil. The pore structure of biochar is highly developed and the specific surface area is very large The surface of biochar contains a variety of organic functional groups, which has strong ion adsorption and exchange capabilities[ 31 – 34 ]. These unique physicochemical properties allow it to be applied to the soil as a soil amendment[ 35 ]. However, the effect of biochar on soil water holding capacity is closely related to the soil texture and the properties of biochar itself[ 36 – 41 ]. Studies have shown that biochar can reduce the saturated hydraulic conductivity of sandy soils, but can improve the hydraulic conductivity of loamy and clayey soils[ 42 ]. Rafael et al. found that biochar can reduce the infiltration capacity of sandy soil but can significantly increase the infiltration capacity of small mound soil through soil column simulation tests[ 43 ]. For clayey raw soils, the amount of biochar applied and the number of years of utilization will inevitably improve the soil structure, causing changes in soil capacitance and soil porosity[ 44 ], which leads to changes in the infiltration capacity and water holding capacity of the soil. However, there are relatively few studies on the effects of biochar usage and service life on water infiltration in clay soils.In this study, the infiltration process affecting soil water movement was studied based on indoor soil column tests with different biochar addition levels, and different models were used to simulate the infiltration process, so as to determine the applicability of the infiltration model under the biochar addition conditions, in order to provide a useful reference for improving soil water status in farmland, optimizing irrigation management and soil improvement in arid regions. 2. Materials and Methods 2.1. Overview of the study area The research area is located in Wangcun, Tangyu Town, Meixian County, Baoji City, Shaanxi Province, at 107°39′-108° 00′E and 33°59′-34°19′N. It is located in the western part of Guanzhong flatland of Shaanxi Province, bordering the Qinling Mountains in the south and the Weishui in the north, and belongs to the middle reaches of the Yellow River in the Sichuan Plateau Gully Area. 2.2. Test materials The soil tested in this study was collected from five different biochar treatment plots in Qinling Field monitoring Central Station. The clay in the soil is mainly kaolinite. The biochar used in the test was purchased from Shaanxi Yixin Bioenergy Technology Development Co., Ltd.,Biochar is apple wood charcoal, carbonization temperature is 450 ~ 480 ℃, carbonization time is 8 ~ 10 h, carbon mass fraction is 85.2%, biochar grinding after 2 mm sieve. Soil water infiltration under different biochar addition levels was studied. The soil particle composition was determined by Mastersizer 2000 laser particle size analyzer. According to the United States Soil Standard (USDA), the soil type was loam. The contents of sand, silt and clay were 18.4%, 74.5% and 7.1%, respectively. The composition of clay minerals is complex, the particle size is not consistent, often contains sand, silt, clay, etc. Clay has water absorption and adsorption, after adding water has plasticity, mainly by kaolinite, Muscovite, montmorillonite, time and feldspar composition. With strong plasticity, water absorption, expansion, shrinkage, adsorption, frost heaving, sintering, fire resistance and other special properties. Biochar contains a large number of carboxyl groups, carbonyl groups, endolipids, hydroxyl groups, ketones and other functional groups, most of which are oxygen-containing functional groups or alkaline functional groups, so that biochar has good adsorption, hydrophilic or hydrophobic, acid-base buffer, ion exchange and other characteristics. The number of functional groups on the surface of biochar is closely related to the carbonization temperature. As the carbonization temperature increases, the C-O bonds, C-H bonds and O-H bonds of biochar decrease, the number of oxygen-containing functional groups such as hydroxyl and carboxyl groups decrease, the acidic groups decrease, the basic groups increase, and the number and density of total functional groups decrease. In the field of soil science, scanning electron microscopy (SEM) has been applied in soil micromorphology, collapsibility structure of loess and ultracharacteristics of mineral weathering. The microstructure of clay and biochar can be observed in Fig. 1 . Polar groups such as hydroxyl and carboxyl groups on biochar can interact with the surface of clay particles through electrostatic interaction and van der Waals force, thus affecting water infiltration. 2.3. Experimental design 2.3.1 Field experiments This study adopted the method of soil column simulation combined with field test. 15 check plots were set up in the field test, with the plot size of 3 m*1.5 m. Five treatments (labeled B0, B5, B10, B15, and B20, respectively) were set according to the amount of biochar used in 0, 5, 10, 15, and 20 t/hm 2 , an unordered group design was adopted, and three replicates per treatment. The biochar was spread evenly on the soil surface, mixed with the cultivated soil (20 cm) by hand to make all parts of the soil color even, and then the plots were set. The manual mixing approach is based on two practical considerations. The primary reason is that the application of large-scale mechanical mixing of biochar cannot maximize the accuracy of the experiment and can not ensure that biochar and soil can be mixed evenly in accordance with the required ratio. Another important reason is that the layout of the test field is not suitable for large machinery. Prior to sampling, fertilizer management in the test plots was based on a base fertilizer that was generally available locally. The N, K, and P fertilization schemes were used in the experimental plots as the local farmers, The fertilizer is pellet. N: 150 kg/hm 2 ; K 2 O: 90 kg/hm 2 and P 2 O 5 : 120 kg/hm 2 . All the soil measured in the laboratory soil column test came from the test field. Five different biochar addition treatments were set up in the experimental field. Samples were taken from 0 -20cm depth of surface layer. Three soil samples were repeated for each treatment. After removing debris from the soil sample, air dry, roll, and pass through a 2mm sieve. 2.3.2 Soil column simulation experiment The soil moisture infiltration test device consists of soil column and Markov bottle(Fig. 2 ). A clear Plexiglas column with an inner diameter of 10 cm and a height of 60 cm was used for soil column simulation experiment, and the soil was filled to a height of 50 cm. 1 layer of 300 mesh nylon mesh and filter paper was placed at the bottom of the soil column before filling. To reduce the wall effect, the inside of the column was coated with petroleum jelly. The specification of the plexiglass soil column was designed by referring to many references and combining with the parameters used in the literature[ 45 – 47 ]. Markov bottle was used for continuous water supply with a constant water head of 5 cm, and the infiltration source was distilled water. Biochar and soil samples were calculated and weighed in a layer of 5 cm for each soil column. After evenly mixed, the samples were loaded into the soil column. Hair was carefully ground at the stratified interface to ensure close contact between soil layers and avoid stratification during the test. Markov bottle principle: As shown in Fig. 1 , a water inlet is set at the top of the mouth of the closed Martensite bottle to make it easy to give the Martensite bottle water, and an air inlet and valve are set on the side wall of the lower end to control the air pressure in the Martensite bottle. When water in the Mahalobis bottle and water in the soil column water chamber are connected into a water supply system, the pressure relationship at each point after system equilibrium is: P c + h 1 = P b =P a (1) Among them: Pa (Pa(cm) 2 ): atmospheric pressure. Pc,Pb (Pa(cm) 2 ): Atmospheric pressure at the height of positions c and b. P 1 (Pa(cm) 2 ): Air pressure in the upper part of the closed container. h 1 (cm): The height of the water column above point b in the bottle. After the work starts, when the water in the soil bucket is slightly reduced due to infiltration, the water in the Markov bottle flows to the soil bucket under the action of potential energy, so that the water in the soil bucket is stable in the original position, and the water in the soil bucket still maintains the original water level. Due to the infiltration of water in the soil bucket, the water in the Markov bottle replenishes the water in the soil bucket, which reduces the water level in the Markov bottle that is, the decrease of h 1 . Pc + h 1 < pb, at this time, the air pressure in the Markov bottle is smaller than atmospheric pressure, and the outside air will enter the Markov bottle through the air inlet on the side wall of the Markov bottle to increase the pc, so as to achieve a new balance. When the water in the soil bucket continuously infiltrates into the soil column, the balance process is the same as above. In this way, the value of h1 can be measured according to the reading of the Markov bottle. It is the infiltration amount of the vertical soil column. The device of the test system is shown in Fig. 1 . The specific operation steps are as follows: (1) Open the inlet hole and water inlet of the Mars bottle, use the funnel to fill the Mars bottle with water. When the Mars bottle is full of water, close the inlet hole and air inlet hole, check and ensure that the Mars bottle does not leak. By adjusting the position of the Mars bottle, the air inlet hole of the Mars bottle and the soil bucket are designed to be flush with the water surface to ensure zero head water supply. The amount of water into the soil body can be accurately measured by using the Mars bottle. (2) Filling of soil sample. To begin filling, first weigh the weight of the soil to be filled in the layer, after each layer of filling, it should be leveled first, then struck with a stone hammer, so that the fill is flush with the intended line of the layer, and then make surface roughness with appropriate tools, and then proceed to fill the next layer of soil, when filling the soil, it should ensure good contact between layers, and should not appear obvious layering phenomenon. (3) System connection. After the soil sample is filled, place an asbestos net or qualitative filter paper on the top of the soil sample to prevent the water from washing over the surface of the sample when it is filled with water. Then use a rubber hose to connect the water outlet of the Mars bottle to the water inlet of the soil bucket. (4) Observe and record the test data. Record the start time of the experiment, start infiltration, observe the depth of the wetting front and the water level of the marsupial, and record the transport depth and water level scale under the corresponding time according to the principle of dense in the front and sparse in the back. The infiltration process ended when the wet front reaches the base of the column. 2.4. Observation indicators and methods Soil moisture content and soil capacity: The drying method was used to determine the soil moisture content of 0–20cm, 20–40cm and different soil layers of agricultural soils during the maturity of maize, and to determine the soil capacity of the corresponding soil layers. Soil moisture infiltration performance parameters. Soil moisture content calculation method: Using the drying method, the collected soil was dried at 100℃- 105℃ for 12 hours until the weight no longer changed, and the dry soil weight was weighed and recorded. W=(M-Ms)/ Ms*100% (2) Where W is the soil water content (%); M is the soil wet weight (g); Ms is the soil dryweight (g). Soil bulk density calculation method. R = (G-G 0 ) / V (3) Where: R is the soil capacity (g/cm 3 ); G is the sum of ring knife and soil weight after drying (g); G 0 is the weight of ring knife (g); V is the volume of ring knife (cm 3 ). 2.5. Parameter Fitting Model Philip infiltration model, The formula I ( t ) is the rate of infiltration (cm/min), S is the rate of soil moisture absorption (cm/min 1/2 ), Closely related to the nature of the soil itself. t indicates the time of infiltration (min); i c is the rate of steady infiltration (cm/min); S and i c can be measured by infiltration test. Kostiakov infiltration model, The equation: k is the accumulated infiltration volume of the first timing unit (cm), n is the empirical constant. Horton infiltration model, The equation: i a is the rate of assumed initial infiltration (cm/min), α is the decay index. 2.6. Data processing and analysis All experimental data were averaged over three replications, plotted using Origin software, and simulated by R software for soil infiltration parameters and statistical analysis. 3. Results 3.1. Effect of different biochar addition methods on soil physical properties Figure 3 depicts the changes in soil bulk density, water content, and porosity at different treatments for soils with depths of 0–20 and 20–40, respectively. For soils in the 0-20cm depth, the soil bulk weight decreased constantly with the increase of biochar utilization, the soil water content did not show obvious gradient characteristics, the soil porosity increased gradually with the increase of biochar utilization. For soils with 20-40cm soil depth, there were no momentous changes in soil bulk, water content, and porosity with the increase of biochar utilization. 3.2.Effect of biochar content on the wetting front process Wetting front progress respond to soil moisture infiltration patterns. Figure 4 shows the variation of the wetting front with time. The trend of the wetting front process is similar for all treatments in the figure, i.e., the slope of the wetting front process curve decreases with infiltration time. The process of wetting front was significantly different among treatments with the same infiltration time, and the process of wetting front of B0 was significantly faster than that of adding biochar, and the more biochar was added, the slower the process of wetting front was. It can be seen from Fig. 4 that the infiltration time of B0, B5, B10, B15 and B20 were 150, 175, 192, 223 and 298 min, respectively, which also indicates that the more biochar was added the slower the wetting front process. 3.3. Effect of biogenic carbon content on cumulative soil infiltration Figure 5 shows the relationship between the cumulative infiltration volume and infiltration time under different biochar contents. The cumulative infiltration volume of all treatments increased with the increase of infiltration time, but the increase degree of cumulative infiltration volume at different infiltration time was significantly different. The slope of cumulative infiltration curve was large in the initial stage of infiltration. After entering the stable infiltration stage, the slope of the cumulative infiltration curve decreased, that was, the cumulative infiltration volume was proportional to the infiltration time and inversely proportional to the biochar addition. The cumulative infiltration volume of 150 min was selected to quantify the soil water infiltration qualities. The cumulative infiltration volume of B0, B5, B10, B15 and B20 at 120 min were 17 cm, 15.65 cm, 14.35 cm, 12.87 cm and 11.34 cm, respectively. 3.4.Soil water infiltration process fitting and infiltration performance analysis To fully understand the effect of biochar addition on soil water infiltration and determine the applicability of the infiltration model, three models, Philip, Kostiakov, and Horton, were used to fit the soil water infiltration process (Table 1 ). The s value in Philip's model ranged from 0.532 to 1.026 and decreased with the increase of biochar addition. The larger the s value was, the larger the slope of the soil infiltration curve was and the faster the instantaneous infiltration rate decayed. The order of instantaneous infiltration rate was B0 > B5 > B10 > B15 > B20. The i c value ranged from 0.148 to 0.502, which was increased significantly with the increase of biochar addition, showing a significant positive correlation. In Kostiakov model, the range of a value was 0.589–1.09. It was also increased with the increase of biochar addition. The range of i c value in the Horton model was 0.825–12.99, which was positively correlated with biochar addition. The range of α value was 0.375–0.532, which was negatively correlated with of biochar addition. Combining the fitting results of the three models, it can be found that the Kostiakov model has the best fitting effect. Table 1 Fitting results of different infiltration model parameters Model Parameters Different treatments B0 B5 B10 B15 B20 Philip s 0.902 ± 0.124 0.873 ± 0.133 0.81 ± 0.112 0.75 ± 0.124 0.642 ± 0.11 i c 0.176 ± 0.028 0.213 ± 0.0101 0.32 ± 0.016 0.39 ± 0.0012 0.49 ± 0.01 R 2 0.943 0.953 0.943 0.896 0.88 RRMSE 0.0275 0.0264 0.0257 0.051 0.055 Kostiakov a 0.980 ± 0.111 0.896 ± 0.017 0.812 ± 0.135 0.73 ± 0.032 0.71 ± 0.12 b 0.569 ± 0.025 0.587 ± 0.012 0.571 ± 0.021 0.592 ± 0.011 0.572 ± 0.01 R 2 0.988 0.992 0.976 0.986 0.986 RRMSE 0.0136 0.0115 0.021 0.031 0.015 Horton i c 0.927 ± 0.102 6.198 ± 0.330 8.21 ± 0.261 9.57 ± 0.36 12.74 ± 0.25 α 0.495 ± 0.037 0.438 ± 0.013 0.412 ± 0.011 0.411 ± 0.019 0.396 ± 0.02 R 2 0.92 0.96 0.94 0.91 0.94 RRMSE 0.0386 0.033 0.043 0.046 0.03 3.5.Effect of biochar content on soil moisture characteristic curve The soil water characteristic curve reflects the relationship between soil water absorption and soil water content, which can be used to understand soil moisture characteristics. There were significant differences in soil moisture characteristic curves among different treatments. When the soil moisture content was close to 0.17, the slope order of the suction curves of different treatments changed significantly. The slope of the originally large slope curve quickly decreased, while the slope of the originally small slope curve quickly increased. The most obvious part was circled in red (Fig. 6 ). 4. Discussion Soil infiltration process is generally affected by internal and external factors, among which external factors include precipitation intensity, vegetation coverage, slope, etc. [ 48 – 51 ], while internal factors include soil texture, bulk density, porosity, structure, initial soil moisture, etc., and internal factors are the main factors affecting soil infiltration capacity [ 52 , 53 ]. Biochar, because of its special physicochemical properties, has been widely used as a soil conditioner to improve soil quality [ 54 , 56 ]. The effect of biochar on the improvement of soil physicochemical properties is affected by many factors such as biochar properties, addition amount, addition duration and soil environmental conditions [ 57 ]. The addition of biochar, due its porosity structure, can change the bulk density, porosity and water holding capacity of soil. The addition of biochar can also improve the chemical properties of soil, due to external elements’ addition. The biochar, due to its active surface, will continuously affect the physicochemical properties of soil. The difference of addition way and amount of biochar change the spatial distribution of biochar of biochar in soil layer, and change the physicochemical properties of soil, and then have a different influence on soil water infiltration. In this study, it was verified that different ratios of biochar addition had different effects on the wetting front and cumulative infiltration. This conclusion verified previous studies [ 58 ]. Due to the abundant porosity and huge specific surface area of biochar, the soil added with biochar had a strong water holding ability. At the initial stage of infiltration, due to the dry soil itself, the biochar addition treatment did not respond immediately. When the infiltration time exceeded 25min, the hydrophilicity of biochar began to play an effective role, and different additions showed obvious gradient differences. The greater the amount of biochar added, the slower the infiltration rate. The results showed that the addition of biochar had an obvious retarding effect on soil water infiltration. The research of Li et al. [ 59 ] also proved that biochar addition could significantly improve soil water holding ability. At the same time, this study also found that the infiltration rate significantly decreased when the infiltration time exceeded 50 min, and the infiltration rate slowed down with the increase of biochar addition. The results of soil infiltration simulation showed that the goodness of fit test R2 of the three infiltration models were all more than 0.9. The infiltration process of soil water under the conditions of different amounts of biochar added can be accurately simulated. For the Kostiakov model, the greater the amount of biochar added, the smaller the value of the coefficient a, indicating that the addition of biochar reduced the infiltration rate of soil water. The coefficient b increased slowly with the increase of biochar addition. When the addition amount of biochar was 15 t/hm2 (B15), the b value was the maximum and the infiltration rate decreased the fastest. The simulation accuracy of Horton model and Philip model was lower than that of Kostiakov model, which was similar to that of the study of Wei et al. [ 60 ]. In this study, we only considered the response of different biochar addition ways and addition amounts to water infiltration of clayey raw soil in Guanzhong Plain, and the detailed simulation of evaporation process should also be studied. Further studies should consider the influence of different addition amounts of biochar on the infiltration and evaporation process of different soil types. 5. Conclusions In this paper, through the indoor soil column simulation test, the influence of different biochar addition levels on the soil water infiltration process was studied, and the applicability of different infiltration models under the biochar addition conditions was verified. The conclusions are as follows: (1) The initial infiltration rate, stable infiltration rate, average infiltration rate and cumulative infiltration amount decreased gradually with increasing the amount of biochar added to the soil, and the wetting front process slowed down. (2) Comparing the three infiltration models with R2 values and model parameters, the simulated water infiltration processes of clayey soil with biochar addition were in the order of Kostiakov model, Philip model and Horton model. (3) By fitting the soil water characteristics curve after biochar addition, it was found that the addition of biochar significantly improved soil water holding and water retention, and the higher the amount of biochar addition, the more obvious the improvement of soil water holding and water retention. Declarations Author Contributions: Conceptualization, J.L.S. and J.L.; Methodology, J.L.S.; Software, J.L.S.; Validation, J.L.S.; Formal Analysis, J.L.S. and J.L.; Investigation, J.L.S.; Resources, J.L.S. and J.L.; Data Curation, J.L.S. and J.L.; Writing—Original Draft Preparation, J.L.S. and J.L. and S.L.Y.; Writing—Review & Editing, J.L.S. and J.L..; Visualization, J.L.S. and J.L.; Supervision, J.L.S. and J.L.; Project Administration, J.L.S.; Funding Acquisition, J.L. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by Shaanxi Land Engineering Construction Group Co., Ltd. and Xi'an Jiaotong University (2021WHZ0093), Shaanxi Province Innovative Talents Program-Youth Science, Internal scientific research project of Shaanxi Land Engineering Construction Group Co., Ltd(DJNY2022-25) and Technology Rising Star Project (2021KJXX-88). Data Availability Statement: All data and material generated or used during the study appear in the submitted article. Acknowledgments: The research was supported by Qinling Mountain Field Monitoring Center, Key Laboratory of Degraded and Unused Land, Ministry of Natural Resources. Conflicts of Interest: The authors declare no conflict of interest. References Vandga A, Owe M. Bare soil surface resistance to evaporation by vapor diffusion under semiaridconditions.Water Resources Research, 1994, 30(2): 181–188. Razzaghi F, Obour P. B, Arthur E. Does biochar improve soil water retention? A systematic review and meta-analysis. Geoderma, 2020, 361, 114055. Liu Y, Guo L, Huang Z, et al. Root morphological characteristics and soil water infiltration capacity in semi-arid artificial grassland soils[J]. Agricultural Water Management, 2020, 235: 106153. Thidar M, Gong D, Mei X, et al. Mulching improved soil water, root distribution and yield of maize in the Loess Plateau of Northwest China[J]. 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Land restoration by tree planting in the tropics and subtropics improves soil infiltration, but some critical gaps still hinder conclusive results. Forest Ecology and Management 2019, 444, 89–95. Zhai Q, Rahardjo H, Satyanaga A, et al. Framework to estimate the soil-water characteristic curve for soils with different void ratios[J]. Bulletin of Engineering Geology and the Environment, 2020, 79: 4399–4409. Zhang C, Lu N. Soil sorptive potential: Its determination and predicting soil water density[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2020, 146(1): 04019118. Toková L, Igaz D, Horák J, et al. Effect of biochar application and re-application on soil bulk density, porosity, saturated hydraulic conductivity, water content and soil water availability in a silty loam Haplic Luvisol[J]. Agronomy, 2020, 10(7): 1005. Farid H U, Mahmood-Khan Z, Ahmad I, et al. Estimation of infiltration models parameters and their comparison to simulate the onsite soil infiltration characteristics[J]. International Journal of Agricultural and Biological Engineering, 2019, 12(3): 84–91. Ngo-Cong D, Antille D L, Th. van Genuchten M, et al. A modeling framework to quantify the effects of compaction on soil water retention and infiltration[J]. Soil Science Society of America Journal, 2021, 85(6): 1931–1945. Angelaki A.; Sihag P.; Sakellariou M.M.; et al. The effect of sorptivity on cumulative infiltration. Water Supply 2021, 21, 606–614. Cao D.F.; Shi B.; Zhu H.H.; et al. Feasibility Investigation of Improving the Modified Green-Ampt Model for Treatment of Horizontal Infiltration in Soil. Water 2019, 11, 645–652. Rafael V.; Luis A.; Esteban M. et al. Diffusivity and sorptivity determination at different soil water contents from horizontal infiltration. Geoderma 2019, 338,88–96. Haimanote K.; Bayabil Y.T.; Dile T.Y.; et al. Evaluating infiltration models and pedotransfer functions: Implications for hydrologic modeling. Geoderma 2019, 338, 159–169. Wang F, Dai Z, Takahashi I, et al. Soil moisture response to water infiltration in a 1-D slope soil column model. Engineering Geology, 2020, 267: 105482. Ma J, Zeng R, Yao Y, et al. Characterization and quantitative evaluation of preferential infiltration in loess, based on a soil column field test[J]. Catena, 2022, 213: 106164. Liu D, Mou S, Zou Y, et al. Exploring the relationship between deep roots and shoot growth of wheat under different soil moisture: A large soil column experiment 1[J]. Rhizosphere, 2023: 100675. Stewart R. D.; Rupp D.R., Najm M.R.A.; et al. Modeling effect of initial soil moisture on sorptivity and infiltration. WATER RESOURCES RESEARCH 2013, 49, 7037–7047. [29] Govaerts B.; Fuentes M.; Mezzalama M.; et al. Infiltration, soil moisture, root rot and nematode populations after 12 years of different tillage, residue and crop rotation managements. Soil and Tillage Research 2007, 94, 209–219. [30] Stahli M.; Jansson P.E., Lundin L.C. Soil moisture redistribution and infiltration in frozen sandy soils. Water Resources Research. 1999, 35, 95–103. [31] Wei L.; Yang M.Y.; Li Z., et al. Experimental Investigation of Relationship between Infiltration Rate and Soil Moisture under Rainfall Conditions. Water. 2022, 14, 1347. [32] Wang S.; Fu B.J.; Gao G.Y.; et al. Responses of soil moisture in different land cover types to rainfall events in a re-vegetation catchment area of the Loess Plateau, China. Catena. 2013, 101,122–128. [33] Cao J.H.; Chen P.P.; Li Y.P.; et al. Effect of Plastic Film Residue on Vertical Infiltration Under Different Initial Soil Moisture Contents and Dry Bulk Densities. Water. 2020, 12, 1346. [34] Kamali M.; Sweygers N.; Al-Salem S.; et al. Biochar for soil applications-sustainability aspects, challenges and future prospects. Chemical Engineering Journal, 2022, 428, 131189. [35] Ji M.; Wang X.; Usman M.; et al. Effects of different feedstocks-based biochar on soil remediation: A review. Environmental Pollution, 2022, 294, 118655. [36] Yang Y.; Sun K.; Han L.; et al. Biochar stability and impact on soil organic carbon mineralization depend on biochar processing, aging and soil clay content. Soil Biology and Biochemistry, 2022, 169, 108657. [37] Singh H.; Northup B.K.; Rice C.W.; et al. Biochar applications influence soil physical and chemical properties, microbial diversity, and crop productivity: a meta-analysis. Biochar, 2022, 4, 8. [38] Pinnington E.; Amezcua J.; Cooper E.S., et al. Improving soil moisture prediction of a high-resolution land surface model by parameterising pedotransfer functions through assimilation of SMAP satellite data. Hydrology and Earth System Sciences. 2021, 25, 1617–1641. [39] Li S.L.; Wang X.; Wang S.; et al.Effects of biochar application mode and dosage on soil moisture infiltration and evaporation.Transactions of the CSAE. 2016, 32, 135–144. [40] Wei Y.X.; Wang H.; Liu H.; et al. Effect of Biochar on Soil Moisture and Its Infiltration Performance in Black Soil Area. Transactions of the Chinese Society for Agricultural Machinery. 2019, 50, 290–300. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-3981210","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":276800467,"identity":"37dbccc2-2a59-4991-8043-078d98d66ded","order_by":0,"name":"Juan Li","email":"","orcid":"","institution":"Ministry of Natural Resources","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Li","suffix":""},{"id":276800468,"identity":"6edde318-a342-44df-b768-09a5c3405976","order_by":1,"name":"Jianglong Shen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYDACCSD+wMAM4SQUEKmFcQZciwGRWph5YFoYiNEiP7v52GObCuvEBvbuxA8PDBjkzQlpMbhzLN0450x6YgPP2c0SQIcZ7mwgpEUix0w6t+1wYoNE7gaQlgSDA4QcNiP/m7TlP6AW+bebfxClheFGDps0YwPIFt5txNlicCPNTLIH6J82ntxtFgkGEoYbCDss+ZnEjxpr2X72s5tv/qiwkSfsMBhgg1ASxKofBaNgFIyCUYAPAABTxjxdDKsNiwAAAABJRU5ErkJggg==","orcid":"","institution":"Ministry of Natural Resources","correspondingAuthor":true,"prefix":"","firstName":"Jianglong","middleName":"","lastName":"Shen","suffix":""},{"id":276800469,"identity":"f25b117c-c782-418b-b757-f9fbcf19f3fc","order_by":2,"name":"Shenglan Ye","email":"","orcid":"","institution":"Ministry of Natural Resources","correspondingAuthor":false,"prefix":"","firstName":"Shenglan","middleName":"","lastName":"Ye","suffix":""}],"badges":[],"createdAt":"2024-02-23 08:47:31","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3981210/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3981210/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52213635,"identity":"7296ba92-47a4-414e-821f-a17b15aeba20","added_by":"auto","created_at":"2024-03-08 02:32:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":769291,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructure of clays and biochar\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/9a35b7e4fd5fc417d43e29ee.png"},{"id":52213633,"identity":"66d981be-9748-4b08-ad7c-2fc66ffaa633","added_by":"auto","created_at":"2024-03-08 02:32:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":84022,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of vertical soil column infiltration test setup\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/1cfed08c88329623c53a4d08.png"},{"id":52213722,"identity":"6f61f365-bcd8-4fad-a2e0-af5b0934c91a","added_by":"auto","created_at":"2024-03-08 02:40:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":185143,"visible":true,"origin":"","legend":"\u003cp\u003eSoil physical properties under different treatments\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/84badd704b232d17426b9926.png"},{"id":52213632,"identity":"13267551-eece-4c53-9125-872e5dba1009","added_by":"auto","created_at":"2024-03-08 02:32:16","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":117297,"visible":true,"origin":"","legend":"\u003cp\u003eDynamic changes of wetting fronts under different biochar utilization rates\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/ff63601964fc51b0f60a9898.png"},{"id":52213637,"identity":"00db488c-1950-4155-85a5-4f18f5bad000","added_by":"auto","created_at":"2024-03-08 02:32:16","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":183468,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of biochar utilization rate on cumulative infiltration\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/cb22a9f27be8f4e4367f3f58.png"},{"id":52213636,"identity":"ab8033a0-35ee-4850-a9a7-e98dd4e137ea","added_by":"auto","created_at":"2024-03-08 02:32:16","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":157944,"visible":true,"origin":"","legend":"\u003cp\u003eSoil moisture characteristic curves of different biochar treatments\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/edb5cbd6d6a47367ef8d541f.png"},{"id":68516441,"identity":"0bf263f4-4c70-42cf-8522-b7981c73034b","added_by":"auto","created_at":"2024-11-08 06:54:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1954619,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3981210/v1/122c6f61-6a13-42f3-9254-c8660aca8427.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Response of biochar-amended clayey soils to water infiltration","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe arid and semi-arid region in northwest China is an important grain producing area in China. For a long time, there exist some problems such as uneven seasonal distribution of rainfall, low utilization efficiency of irrigation water and great loss of soil evaporation. Therefore, it is of great significance to regulate field water condition reasonably and improve soil water holding capacity.[\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Raw soil in general shows low fertility level, hard or too loose soil, soil water infiltration rate is small, unable to plant crops for effective water supply and nutrition supplement. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Under natural conditions, the maturation process of raw soil is slow, making it difficult to meet the expectations of cultivators and the needs of agricultural development[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Through time verification, it is found that biochar soil amendments can improve the quality of newly cultivated land and wasteland rapidly, which is an effective soil restoration method with minimum sacrifice[\u003cspan additionalcitationids=\"CR9 CR10 CR11 CR12\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Infiltration is an important cyclic process of water in farmland soil, and the infiltration process determines the effective degree of soil acceptance of rainfall and irrigation water, and also affects surface runoff and soil water erosion processes[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Take effective measures to improve soil infiltration characteristics is an effective way to improve the soil's ability to store water and retain moisture and promote stable and high yields[\u003cspan additionalcitationids=\"CR16 CR17 CR18 CR19 CR20 CR21\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Different soil textures have a significant impact on soil moisture infiltration capacity [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Afrin et al. analyzed and discussed the soil texture on the ability of water infiltration in farmland soil based on the infiltration test data of field soil water accumulation under different soil texture conditions, and found that the infiltration rate of soil steadily decreases and the infiltration capacity decreases when the soil texture changes from light to heavy[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The greater the clay particle content of the soil, the smaller the cumulative infiltration volume of the soil in the same infiltration time, i.e., the more viscous and heavy the soil is, the worse its infiltration capacity[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. For raw soils with relatively clayey texture and compact soil, the lack of agglomeration and low infiltration rate affects the acceptance of precipitation and irrigation water, and easily generates surface runoff, resulting in degradation of raw soil quality[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Therefore, how to improve its water storage capacity is the key to improve the quality of clayey raw soil.\u003c/p\u003e \u003cp\u003eThe pore structure of biochar is highly developed and the specific surface area is very large The surface of biochar contains a variety of organic functional groups, which has strong ion adsorption and exchange capabilities[\u003cspan additionalcitationids=\"CR32 CR33\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. These unique physicochemical properties allow it to be applied to the soil as a soil amendment[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. However, the effect of biochar on soil water holding capacity is closely related to the soil texture and the properties of biochar itself[\u003cspan additionalcitationids=\"CR37 CR38 CR39 CR40\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Studies have shown that biochar can reduce the saturated hydraulic conductivity of sandy soils, but can improve the hydraulic conductivity of loamy and clayey soils[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. Rafael et al. found that biochar can reduce the infiltration capacity of sandy soil but can significantly increase the infiltration capacity of small mound soil through soil column simulation tests[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. For clayey raw soils, the amount of biochar applied and the number of years of utilization will inevitably improve the soil structure, causing changes in soil capacitance and soil porosity[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e], which leads to changes in the infiltration capacity and water holding capacity of the soil. However, there are relatively few studies on the effects of biochar usage and service life on water infiltration in clay soils.In this study, the infiltration process affecting soil water movement was studied based on indoor soil column tests with different biochar addition levels, and different models were used to simulate the infiltration process, so as to determine the applicability of the infiltration model under the biochar addition conditions, in order to provide a useful reference for improving soil water status in farmland, optimizing irrigation management and soil improvement in arid regions.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1. Overview of the study area\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe research area is located in Wangcun, Tangyu Town, Meixian County, Baoji City, Shaanxi Province, at 107\u0026deg;39\u0026prime;-108\u0026deg; 00\u0026prime;E and 33\u0026deg;59\u0026prime;-34\u0026deg;19\u0026prime;N. It is located in the western part of Guanzhong flatland of Shaanxi Province, bordering the Qinling Mountains in the south and the Weishui in the north, and belongs to the middle reaches of the Yellow River in the Sichuan Plateau Gully Area.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2. Test materials\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe soil tested in this study was collected from five different biochar treatment plots in Qinling Field monitoring Central Station. The clay in the soil is mainly kaolinite. The biochar used in the test was purchased from Shaanxi Yixin Bioenergy Technology Development Co., Ltd.,Biochar is apple wood charcoal, carbonization temperature is 450\u0026thinsp;~\u0026thinsp;480 ℃, carbonization time is 8\u0026thinsp;~\u0026thinsp;10 h, carbon mass fraction is 85.2%, biochar grinding after 2 mm sieve. Soil water infiltration under different biochar addition levels was studied. The soil particle composition was determined by Mastersizer 2000 laser particle size analyzer. According to the United States Soil Standard (USDA), the soil type was loam. The contents of sand, silt and clay were 18.4%, 74.5% and 7.1%, respectively.\u003c/p\u003e\n \u003cp\u003eThe composition of clay minerals is complex, the particle size is not consistent, often contains sand, silt, clay, etc. Clay has water absorption and adsorption, after adding water has plasticity, mainly by kaolinite, Muscovite, montmorillonite, time and feldspar composition. With strong plasticity, water absorption, expansion, shrinkage, adsorption, frost heaving, sintering, fire resistance and other special properties. Biochar contains a large number of carboxyl groups, carbonyl groups, endolipids, hydroxyl groups, ketones and other functional groups, most of which are oxygen-containing functional groups or alkaline functional groups, so that biochar has good adsorption, hydrophilic or hydrophobic, acid-base buffer, ion exchange and other characteristics. The number of functional groups on the surface of biochar is closely related to the carbonization temperature. As the carbonization temperature increases, the C-O bonds, C-H bonds and O-H bonds of biochar decrease, the number of oxygen-containing functional groups such as hydroxyl and carboxyl groups decrease, the acidic groups decrease, the basic groups increase, and the number and density of total functional groups decrease.\u003c/p\u003e\n \u003cp\u003eIn the field of soil science, scanning electron microscopy (SEM) has been applied in soil micromorphology, collapsibility structure of loess and ultracharacteristics of mineral weathering. The microstructure of clay and biochar can be observed in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Polar groups such as hydroxyl and carboxyl groups on biochar can interact with the surface of clay particles through electrostatic interaction and van der Waals force, thus affecting water infiltration.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3. Experimental design\u003c/h2\u003e\n \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.1 Field experiments\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThis study adopted the method of soil column simulation combined with field test. 15 check plots were set up in the field test, with the plot size of 3 m*1.5 m. Five treatments (labeled B0, B5, B10, B15, and B20, respectively) were set according to the amount of biochar used in 0, 5, 10, 15, and 20 t/hm\u003csup\u003e2\u003c/sup\u003e, an unordered group design was adopted, and three replicates per treatment. The biochar was spread evenly on the soil surface, mixed with the cultivated soil (20 cm) by hand to make all parts of the soil color even, and then the plots were set. The manual mixing approach is based on two practical considerations. The primary reason is that the application of large-scale mechanical mixing of biochar cannot maximize the accuracy of the experiment and can not ensure that biochar and soil can be mixed evenly in accordance with the required ratio. Another important reason is that the layout of the test field is not suitable for large machinery. Prior to sampling, fertilizer management in the test plots was based on a base fertilizer that was generally available locally. The N, K, and P fertilization schemes were used in the experimental plots as the local farmers, The fertilizer is pellet. N: 150 kg/hm\u003csup\u003e2\u003c/sup\u003e; K\u003csub\u003e2\u003c/sub\u003eO: 90 kg/hm\u003csup\u003e2\u003c/sup\u003e and P\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e: 120 kg/hm\u003csup\u003e2\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eAll the soil measured in the laboratory soil column test came from the test field. Five different biochar addition treatments were set up in the experimental field. Samples were taken from 0 -20cm depth of surface layer. Three soil samples were repeated for each treatment. After removing debris from the soil sample, air dry, roll, and pass through a 2mm sieve.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.2 Soil column simulation experiment\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe soil moisture infiltration test device consists of soil column and Markov bottle(Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). A clear Plexiglas column with an inner diameter of 10 cm and a height of 60 cm was used for soil column simulation experiment, and the soil was filled to a height of 50 cm. 1 layer of 300 mesh nylon mesh and filter paper was placed at the bottom of the soil column before filling. To reduce the wall effect, the inside of the column was coated with petroleum jelly. The specification of the plexiglass soil column was designed by referring to many references and combining with the parameters used in the literature[\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e]. Markov bottle was used for continuous water supply with a constant water head of 5 cm, and the infiltration source was distilled water. Biochar and soil samples were calculated and weighed in a layer of 5 cm for each soil column. After evenly mixed, the samples were loaded into the soil column. Hair was carefully ground at the stratified interface to ensure close contact between soil layers and avoid stratification during the test.\u003c/p\u003e\n \u003cp\u003eMarkov bottle principle:\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, a water inlet is set at the top of the mouth of the closed Martensite bottle to make it easy to give the Martensite bottle water, and an air inlet and valve are set on the side wall of the lower end to control the air pressure in the Martensite bottle. When water in the Mahalobis bottle and water in the soil column water chamber are connected into a water supply system, the pressure relationship at each point after system equilibrium is:\u003c/p\u003e\n \u003cp\u003eP\u003csub\u003ec\u003c/sub\u003e+ h\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;P\u003csub\u003eb\u003c/sub\u003e=P\u003csub\u003ea\u003c/sub\u003e (1)\u003c/p\u003e\n \u003cp\u003eAmong them: Pa (Pa(cm)\u003csup\u003e2\u003c/sup\u003e): atmospheric pressure.\u003c/p\u003e\n \u003cp\u003ePc,Pb (Pa(cm)\u003csup\u003e2\u003c/sup\u003e): Atmospheric pressure at the height of positions c and b.\u003c/p\u003e\n \u003cp\u003eP\u003csub\u003e1\u003c/sub\u003e (Pa(cm)\u003csup\u003e2\u003c/sup\u003e): Air pressure in the upper part of the closed container.\u003c/p\u003e\n \u003cp\u003eh\u003csub\u003e1\u003c/sub\u003e(cm): The height of the water column above point b in the bottle.\u003c/p\u003e\n \u003cp\u003eAfter the work starts, when the water in the soil bucket is slightly reduced due to infiltration, the water in the Markov bottle flows to the soil bucket under the action of potential energy, so that the water in the soil bucket is stable in the original position, and the water in the soil bucket still maintains the original water level. Due to the infiltration of water in the soil bucket, the water in the Markov bottle replenishes the water in the soil bucket, which reduces the water level in the Markov bottle that is, the decrease of h\u003csub\u003e1\u003c/sub\u003e. Pc\u0026thinsp;+\u0026thinsp;h\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;pb, at this time, the air pressure in the Markov bottle is smaller than atmospheric pressure, and the outside air will enter the Markov bottle through the air inlet on the side wall of the Markov bottle to increase the pc, so as to achieve a new balance. When the water in the soil bucket continuously infiltrates into the soil column, the balance process is the same as above. In this way, the value of h1 can be measured according to the reading of the Markov bottle. It is the infiltration amount of the vertical soil column.\u003c/p\u003e\n \u003cp\u003eThe device of the test system is shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. The specific operation steps are as follows:\u003c/p\u003e\n \u003cp\u003e(1) Open the inlet hole and water inlet of the Mars bottle, use the funnel to fill the Mars bottle with water. When the Mars bottle is full of water, close the inlet hole and air inlet hole, check and ensure that the Mars bottle does not leak. By adjusting the position of the Mars bottle, the air inlet hole of the Mars bottle and the soil bucket are designed to be flush with the water surface to ensure zero head water supply. The amount of water into the soil body can be accurately measured by using the Mars bottle.\u003c/p\u003e\n \u003cp\u003e(2) Filling of soil sample. To begin filling, first weigh the weight of the soil to be filled in the layer, after each layer of filling, it should be leveled first, then struck with a stone hammer, so that the fill is flush with the intended line of the layer, and then make surface roughness with appropriate tools, and then proceed to fill the next layer of soil, when filling the soil, it should ensure good contact between layers, and should not appear obvious layering phenomenon.\u003c/p\u003e\n \u003cp\u003e(3) System connection. After the soil sample is filled, place an asbestos net or qualitative filter paper on the top of the soil sample to prevent the water from washing over the surface of the sample when it is filled with water. Then use a rubber hose to connect the water outlet of the Mars bottle to the water inlet of the soil bucket.\u003c/p\u003e\n \u003cp\u003e(4) Observe and record the test data. Record the start time of the experiment, start infiltration, observe the depth of the wetting front and the water level of the marsupial, and record the transport depth and water level scale under the corresponding time according to the principle of dense in the front and sparse in the back. The infiltration process ended when the wet front reaches the base of the column.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e2.4. Observation indicators and methods\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eSoil moisture content and soil capacity: The drying method was used to determine the soil moisture content of 0\u0026ndash;20cm, 20\u0026ndash;40cm and different soil layers of agricultural soils during the maturity of maize, and to determine the soil capacity of the corresponding soil layers.\u003c/p\u003e\n \u003cp\u003eSoil moisture infiltration performance parameters.\u003c/p\u003e\n \u003cp\u003eSoil moisture content calculation method: Using the drying method, the collected soil was dried at 100℃- 105℃ for 12 hours until the weight no longer changed, and the dry soil weight was weighed and recorded.\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eW=(M-Ms)/ Ms*100%\u003c/em\u003e (2)\u003c/p\u003e\n \u003cp\u003eWhere W is the soil water content (%); M is the soil wet weight (g); Ms is the soil dryweight (g).\u003c/p\u003e\n \u003cp\u003eSoil bulk density calculation method.\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eR\u003c/em\u003e=\u003cem\u003e(G-G\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e/\u003cem\u003eV\u003c/em\u003e (3)\u003c/p\u003e\n \u003cp\u003eWhere: \u003cem\u003eR\u003c/em\u003e is the soil capacity (g/cm\u003csup\u003e3\u003c/sup\u003e); \u003cem\u003eG\u003c/em\u003e is the sum of ring knife and soil weight after drying (g); \u003cem\u003eG\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is the weight of ring knife (g); V is the volume of ring knife (cm\u003csup\u003e3\u003c/sup\u003e).\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e2.5. Parameter Fitting Model\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003ePhilip infiltration model,\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"EquationNumber\"\u003e\u003cimg 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w4cABCAAAQhAAAK1EvgfaHoIpeex6agAAAAASUVORK5CYII=\" width=\"682\" height=\"73\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe formula \u003cem\u003eI\u003c/em\u003e(\u003cem\u003et\u003c/em\u003e) is the rate of infiltration (cm/min), \u003cem\u003eS\u003c/em\u003e is the rate of soil moisture absorption (cm/min\u003csup\u003e1/2\u003c/sup\u003e), Closely related to the nature of the soil itself. \u003cem\u003et\u003c/em\u003e indicates the time of infiltration (min); \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e is the rate of steady infiltration (cm/min); S and \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e can be measured by infiltration test.\u003c/p\u003e\n \u003cp\u003eKostiakov infiltration model,\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\n \u003cdiv class=\"EquationNumber\"\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"692\" height=\"49\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe equation: \u003cem\u003ek\u003c/em\u003e is the accumulated infiltration volume of the first timing unit (cm), \u003cem\u003en\u003c/em\u003e is the empirical constant.\u003c/p\u003e\n \u003cp\u003eHorton infiltration model,\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\n \u003cdiv class=\"EquationNumber\"\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"750\" height=\"56\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe equation: \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e is the rate of assumed initial infiltration (cm/min), \u0026alpha; is the decay index.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e2.6. Data processing and analysis\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eAll experimental data were averaged over three replications, plotted using Origin software, and simulated by R software for soil infiltration parameters and statistical analysis.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Effect of different biochar addition methods on soil physical properties\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e depicts the changes in soil bulk density, water content, and porosity at different treatments for soils with depths of 0\u0026ndash;20 and 20\u0026ndash;40, respectively. For soils in the 0-20cm depth, the soil bulk weight decreased constantly with the increase of biochar utilization, the soil water content did not show obvious gradient characteristics, the soil porosity increased gradually with the increase of biochar utilization. For soils with 20-40cm soil depth, there were no momentous changes in soil bulk, water content, and porosity with the increase of biochar utilization.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.2.Effect of biochar content on the wetting front process\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eWetting front progress respond to soil moisture infiltration patterns. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the variation of the wetting front with time. The trend of the wetting front process is similar for all treatments in the figure, i.e., the slope of the wetting front process curve decreases with infiltration time. The process of wetting front was significantly different among treatments with the same infiltration time, and the process of wetting front of B0 was significantly faster than that of adding biochar, and the more biochar was added, the slower the process of wetting front was. It can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e that the infiltration time of B0, B5, B10, B15 and B20 were 150, 175, 192, 223 and 298 min, respectively, which also indicates that the more biochar was added the slower the wetting front process.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Effect of biogenic carbon content on cumulative soil infiltration\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the relationship between the cumulative infiltration volume and infiltration time under different biochar contents. The cumulative infiltration volume of all treatments increased with the increase of infiltration time, but the increase degree of cumulative infiltration volume at different infiltration time was significantly different. The slope of cumulative infiltration curve was large in the initial stage of infiltration. After entering the stable infiltration stage, the slope of the cumulative infiltration curve decreased, that was, the cumulative infiltration volume was proportional to the infiltration time and inversely proportional to the biochar addition. The cumulative infiltration volume of 150 min was selected to quantify the soil water infiltration qualities. The cumulative infiltration volume of B0, B5, B10, B15 and B20 at 120 min were 17 cm, 15.65 cm, 14.35 cm, 12.87 cm and 11.34 cm, respectively.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.4.Soil water infiltration process fitting and infiltration performance analysis\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eTo fully understand the effect of biochar addition on soil water infiltration and determine the applicability of the infiltration model, three models, Philip, Kostiakov, and Horton, were used to fit the soil water infiltration process (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The s value in Philip's model ranged from 0.532 to 1.026 and decreased with the increase of biochar addition. The larger the s value was, the larger the slope of the soil infiltration curve was and the faster the instantaneous infiltration rate decayed. The order of instantaneous infiltration rate was B0\u0026thinsp;\u0026gt;\u0026thinsp;B5\u0026thinsp;\u0026gt;\u0026thinsp;B10\u0026thinsp;\u0026gt;\u0026thinsp;B15\u0026thinsp;\u0026gt;\u0026thinsp;B20. The \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e value ranged from 0.148 to 0.502, which was increased significantly with the increase of biochar addition, showing a significant positive correlation. In Kostiakov model, the range of a value was 0.589\u0026ndash;1.09. It was also increased with the increase of biochar addition. The range of \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e value in the Horton model was 0.825\u0026ndash;12.99, which was positively correlated with biochar addition. The range of α value was 0.375\u0026ndash;0.532, which was negatively correlated with of biochar addition. Combining the fitting results of the three models, it can be found that the Kostiakov model has the best fitting effect.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFitting results of different infiltration model parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eModel\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c10\" namest=\"c5\"\u003e \u003cp\u003eDifferent treatments\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eB0\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eB5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB10\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eB15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eB20\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePhilip\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003es\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.902\u0026thinsp;\u0026plusmn;\u0026thinsp;0.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.873\u0026thinsp;\u0026plusmn;\u0026thinsp;0.133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.81\u0026thinsp;\u0026plusmn;\u0026thinsp;0.112\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.642\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.176\u0026thinsp;\u0026plusmn;\u0026thinsp;0.028\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.213\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.953\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.896\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRRMSE\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.0275\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.0264\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.0257\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKostiakov\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003ea\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.980\u0026thinsp;\u0026plusmn;\u0026thinsp;0.111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.896\u0026thinsp;\u0026plusmn;\u0026thinsp;0.017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.812\u0026thinsp;\u0026plusmn;\u0026thinsp;0.135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eb\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.569\u0026thinsp;\u0026plusmn;\u0026thinsp;0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.587\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.571\u0026thinsp;\u0026plusmn;\u0026thinsp;0.021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.592\u0026thinsp;\u0026plusmn;\u0026thinsp;0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.572\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.988\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.976\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.986\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.986\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRRMSE\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.0136\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.0115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHorton\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.927\u0026thinsp;\u0026plusmn;\u0026thinsp;0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.198\u0026thinsp;\u0026plusmn;\u0026thinsp;0.330\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.261\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.57\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e12.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eα\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.495\u0026thinsp;\u0026plusmn;\u0026thinsp;0.037\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.438\u0026thinsp;\u0026plusmn;\u0026thinsp;0.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.412\u0026thinsp;\u0026plusmn;\u0026thinsp;0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.411\u0026thinsp;\u0026plusmn;\u0026thinsp;0.019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.396\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRRMSE\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.0386\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.043\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.5.Effect of biochar content on soil moisture characteristic curve\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe soil water characteristic curve reflects the relationship between soil water absorption and soil water content, which can be used to understand soil moisture characteristics. There were significant differences in soil moisture characteristic curves among different treatments. When the soil moisture content was close to 0.17, the slope order of the suction curves of different treatments changed significantly. The slope of the originally large slope curve quickly decreased, while the slope of the originally small slope curve quickly increased. The most obvious part was circled in red (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eSoil infiltration process is generally affected by internal and external factors, among which external factors include precipitation intensity, vegetation coverage, slope, etc. [\u003cspan additionalcitationids=\"CR49 CR50\" citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e], while internal factors include soil texture, bulk density, porosity, structure, initial soil moisture, etc., and internal factors are the main factors affecting soil infiltration capacity [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBiochar, because of its special physicochemical properties, has been widely used as a soil conditioner to improve soil quality [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. The effect of biochar on the improvement of soil physicochemical properties is affected by many factors such as biochar properties, addition amount, addition duration and soil environmental conditions [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]. The addition of biochar, due its porosity structure, can change the bulk density, porosity and water holding capacity of soil. The addition of biochar can also improve the chemical properties of soil, due to external elements\u0026rsquo; addition. The biochar, due to its active surface, will continuously affect the physicochemical properties of soil.\u003c/p\u003e \u003cp\u003eThe difference of addition way and amount of biochar change the spatial distribution of biochar of biochar in soil layer, and change the physicochemical properties of soil, and then have a different influence on soil water infiltration.\u003c/p\u003e \u003cp\u003eIn this study, it was verified that different ratios of biochar addition had different effects on the wetting front and cumulative infiltration. This conclusion verified previous studies [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]. Due to the abundant porosity and huge specific surface area of biochar, the soil added with biochar had a strong water holding ability. At the initial stage of infiltration, due to the dry soil itself, the biochar addition treatment did not respond immediately. When the infiltration time exceeded 25min, the hydrophilicity of biochar began to play an effective role, and different additions showed obvious gradient differences. The greater the amount of biochar added, the slower the infiltration rate. The results showed that the addition of biochar had an obvious retarding effect on soil water infiltration. The research of Li et al. [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e] also proved that biochar addition could significantly improve soil water holding ability. At the same time, this study also found that the infiltration rate significantly decreased when the infiltration time exceeded 50 min, and the infiltration rate slowed down with the increase of biochar addition.\u003c/p\u003e \u003cp\u003eThe results of soil infiltration simulation showed that the goodness of fit test R2 of the three infiltration models were all more than 0.9. The infiltration process of soil water under the conditions of different amounts of biochar added can be accurately simulated. For the Kostiakov model, the greater the amount of biochar added, the smaller the value of the coefficient a, indicating that the addition of biochar reduced the infiltration rate of soil water. The coefficient b increased slowly with the increase of biochar addition. When the addition amount of biochar was 15 t/hm2 (B15), the b value was the maximum and the infiltration rate decreased the fastest. The simulation accuracy of Horton model and Philip model was lower than that of Kostiakov model, which was similar to that of the study of Wei et al. [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. In this study, we only considered the response of different biochar addition ways and addition amounts to water infiltration of clayey raw soil in Guanzhong Plain, and the detailed simulation of evaporation process should also be studied. Further studies should consider the influence of different addition amounts of biochar on the infiltration and evaporation process of different soil types.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eIn this paper, through the indoor soil column simulation test, the influence of different biochar addition levels on the soil water infiltration process was studied, and the applicability of different infiltration models under the biochar addition conditions was verified. The conclusions are as follows:\u003c/p\u003e \u003cp\u003e(1) The initial infiltration rate, stable infiltration rate, average infiltration rate and cumulative infiltration amount decreased gradually with increasing the amount of biochar added to the soil, and the wetting front process slowed down.\u003c/p\u003e \u003cp\u003e(2) Comparing the three infiltration models with R2 values and model parameters, the simulated water infiltration processes of clayey soil with biochar addition were in the order of Kostiakov model, Philip model and Horton model.\u003c/p\u003e \u003cp\u003e(3) By fitting the soil water characteristics curve after biochar addition, it was found that the addition of biochar significantly improved soil water holding and water retention, and the higher the amount of biochar addition, the more obvious the improvement of soil water holding and water retention.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u003c/strong\u003e Conceptualization, J.L.S. and J.L.; Methodology, J.L.S.; Software, J.L.S.; Validation, J.L.S.; Formal Analysis, J.L.S. and J.L.; Investigation, J.L.S.; Resources, J.L.S. and J.L.; Data Curation, J.L.S. and J.L.; Writing\u0026mdash;Original Draft Preparation, J.L.S. and J.L. and S.L.Y.; Writing\u0026mdash;Review \u0026amp; Editing, J.L.S. and J.L..; Visualization, J.L.S. and J.L.; Supervision, J.L.S. and J.L.; Project Administration, J.L.S.; Funding Acquisition, J.L. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This research was funded by Shaanxi Land Engineering Construction Group Co., Ltd. and Xi\u0026apos;an Jiaotong University (2021WHZ0093), Shaanxi Province Innovative Talents Program-Youth Science,\u0026nbsp;Internal scientific research project of Shaanxi Land Engineering Construction Group Co., Ltd(DJNY2022-25)\u0026nbsp;and Technology Rising Star Project (2021KJXX-88).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement:\u003c/strong\u003e All data and material generated or used during the study appear in\u0026nbsp;the submitted article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e The research was supported by Qinling Mountain Field Monitoring Center, Key Laboratory of Degraded and Unused Land, Ministry of Natural Resources.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest:\u003c/strong\u003e The authors declare no conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVandga A, Owe M. 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Transactions of the Chinese Society for Agricultural Machinery. 2019, 50, 290\u0026ndash;300.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"biochar, soil moisture, infiltration model, clayey soils","lastPublishedDoi":"10.21203/rs.3.rs-3981210/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3981210/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBiochar is an effective clayey raw soils improver. The difference of the amount of biochar added will cause the difference of soil water infiltration. The effects of mass addition ratios of five types of biochar (B0, B5, B10, B15 and B20) on the migration distance of soil wet front, cumulative infiltration and water holding capacity were studied through laboratory soil column simulation experiments. The soil water infiltration process was simulated as well with R\u003csup\u003e2\u003c/sup\u003eof 0.992, using Philip model, Horton model and Kostiakov model, respectively. The results demonstrate that the initial infiltration rate, stable infiltration rate and cumulative infiltration volume decrease with the increase of biochar addition and provide a reference of biochar utilization to improve soil hydraulic properties and moisture infiltration performance of clayey raw soils.\u003c/p\u003e","manuscriptTitle":"Response of biochar-amended clayey soils to water infiltration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-08 02:32:11","doi":"10.21203/rs.3.rs-3981210/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2941ac34-b1c6-46f1-8b77-a34c18066440","owner":[],"postedDate":"March 8th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":29175017,"name":"Earth and environmental sciences/Environmental sciences"},{"id":29175018,"name":"Earth and environmental sciences/Environmental social sciences"}],"tags":[],"updatedAt":"2024-11-08T06:53:45+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-08 02:32:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3981210","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3981210","identity":"rs-3981210","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}