Effects Of Different Use Level And The Application's Period Of Biochar On Soil Water Movement And Solute Transport

Black soil region of Northeast China is an important commodity grain base in China,which accounts for 1/5 of the total grain production in China.Black soil is rich in organic matter,rich in nutrients,has a rich humus layer and good physical,chemical and biological characteristics,is an important soil resource in China.However,now,the soil and water loss is serious in black soil area,rich in organic matter,nutrient black soil continued erosion,soil bulk density increased,resulting in soil water retention,fertilizer retention capacity continued to decline,the decline in crop yields,a serious threat to national and regional food security and sustainable development of agriculture.<13th Five-Year> plan will strengthen and accelerate the implementation of the protection of the black soil region of northeast increased grain saving included in the focus of promoting the modernization of agriculture.Biological carbon technology utilizes agricultural straw and other wastes to improve the remediation of the soil.At the same time,improve the efficiency of water and fertilizer utilization in low carbon environmental protection,so as to increase the yield of crops.It is an important research direction of sustainable development of agriculture,especially for the rich utilization of straw resources in the black soil region of Northeast China.The test site in Bei'an City,the Red Star Farm,Runoff plot combined with indoor test in the natural condition,analysis for two consecutive years of different biochar fertilization treatments on soil physicochemical properties,effects of parameters of soil water movement and solute transport parameters,and established the soil water movement and solute transport model,analysis the simulation results,obtained the following conclusions:1.With the increase of biochar,the weight of each treatment decreased gradually and the total porosity increased.The application of biochar for two years significantly increased the content of soil water stable aggregates and total organic carbon in soil,and increased significantly.The increase of water stable aggregates was 17.29%~126.20%,and the increase of total organic carbon content was 36.19%~196.63%.The p H,organic matter,available phosphorus and available potassium in different treatments increased with the increase of biochar addition and application time,the organic matter increased most significantly.The soil water holding capacity and saturated water content increased with the increase of biochar.Biochar can effectively improve the soil water holding capacity,water holding capacity,improve the soil water storage performance,is conducive to crop drought,to achieve the purpose of saving water and increasing production.2.The soil water holding capacity of the plough layer was increased with the application of different dosage for two years.The effect of biochar on the reciprocal of the inlet value was the most significant.Compared with the results of two years,the application of biochar could improve the soil water characteristic curve and significantly improve the soil water holding capacity.When the moisture content was less than 0.40 cm3·cm-3,biochar inhibited the soil water movement in the horizontal direction;when the water volume rate is higher than 0.40 cm3·cm-3,biochar improves the horizontal diffusion of soil water.Second years of continuous application of biochar has a certain impact on the water diffusion rate,but when the cumulative application of biochar increased continuously,its effect began to weaken.With the increase of the amount of biochar and the application time,the unsaturated hydraulic conductivity increases gradually,and the range of fluctuation increases gradually.Biochar can improve soil water holding capacity and improve soil hydraulic properties,thus improving soil water use efficiency and crop yield.The diffusion coefficient of the biochar treatment increased than CK,and increased with the increasing of the application of biochar.3.Based on the theory of soil water dynamics,the model of soil water movement and solute transport was established based on the specific conditions of the test area.By comparing the simulated and measured values of soil water and solute content at 20,1 and 12 hours after rainfall,It is found that the model error is within the allowable range,which indicates that the model can be applied in the test area of biochar application,and the model is accurate and reliable.4.According to the simulation results: the soil water content from small to large is CK<C1<C2<C3<C4,with the gradual increase of biochar application time,soil water content increased,biochar application increased soil water content,improve soil water holding capacity,is conducive to better crop water use,to achieve efficient use of water resources objective.The soil solute content of each treatment was CK<C1<C2<C3<C4 from small to large,and the application of biochar reduced the loss of soil nutrients,and the higher the amount of biochar application,the greater the soil solute content.Biochar produces more nutrients in the soil,it is conducive to the retention and occurrence of nutrients,which is more conducive to crop growth and development.