Effects Of Pre-supply Of Biochar On Soil Improvement And Crop Water-saving And Yield-increasing In Black Soil Region

Heilongjiang is the most important production area of commodity grain in China.In recent years,soil degradation and nutrient loss in the black soil area have gradually affected the sustainable use of agricultural land and water resources and sustainable economic development.As a new carbon storage agent and soil amendment,biochar provides new ideas and possibilities for solving the above problems.In recent years,experiments on the supply of biochar in agricultural production have gradually increased,but mainly indoor tests and short-term tests are mainly based,and field long-term positioning tests are rare.Therefore,this article selects the field where biochar has been added for three consecutive years in the experimental site of the Heilongjiang Institute of Hydraulic Research to test soil physical and chemical properties,soil moisture,redistribution of soil moisture after rain,crop biological traits,yield and water use.Indicators of efficiency,etc.,explore the post-effects of biochar on the soil and crops.The preliminary conclusions obtained are as follows:(1)The pre-supply of biochar can reduce soil bulk density,increase soil porosity,increase soil water holding capacity,saturated moisture content,and effective water content.The large aggregates and the average weight diameter of soil have also been effectively improved due to the previous supply of biochar.However,under high carbon supply conditions,the number of macroaggregates in the soil will decrease,and the stability will deteriorate.The supply of biochar in the early stage will still increase the soil p H and the content of organic matter,ammonium nitrogen and available potassium,among which the increase of the available potassium content is the most significant,reaching a maximum of 42.50%.The effective phosphorus content did not change significantly due to the previous supply of biochar.(2)The pre-supply of biochar can increase the water content and water storage in all soil layers.Compared with the CK in the control group,the soil water content and water storage of all treatments increased.The soil moisture content generally shows the pattern of SK3>SK4>SK2>SK1>CK,while the storage volume generally shows the pattern of SK3>SK2>SK1>SK4>CK.With the increase of soil depth,the differences of soil water content and water storage between the treatments gradually decreased,indicating that the supply of biochar in the early stage has a greater impact on the shallow soil moisture,and has little effect on the soil moisture in deep soils,especially in the 60-80 cm soil layer.However,under the condition of high carbon supply rate,the water storage capacity of 0-20 cm soil layer sometimes appears to be lower than that of CK treatment,indicating that the excessively high carbon supply amount in the early stage may produce certain negative effects.(3)The pre-supply of biochar can effectively increase the plant height,stem diameter,leaf area index and dry matter accumulation of soybean in the range of suitable amount of carbon applied.It also effectively increased soybean yield,number of pods per plant,number of grains per plant,and water use efficiency.The SK2 treatment of each treatment has the most significant effect on the above indicators.Under the conditions of high carbon supply rate,various biological characteristics and biomass of soybean will be inhibited,resulting in a reduction in yield and its constituent elements.There was no significant difference in water consumption during the whole growth period of each treatment,but due to the relatively low yield of high carbon fertilizer treatment,its water efficiency decreased to a certain extent compared with CK.(4)The pre-supply of biochar stage can promote the infiltration of soil moisture after rain,but as the water redistribution time prolongs,biochar shows its holding effect on water,effectively reducing the loss of shallow soil moisture,making more Water remains in the plough layer,providing a better moisture environment for the crop.The water content of shallow soil was higher than that of CK in the suitable amount range at the 7th day after rain,but the range of soil moisture content in 60-80 cm soil layer was small and did not show obvious rules.(5)In this paper,indoor experiment was used to measure the soil water movement parameters.Using field experiment and software simulation method,the soil redistribution within 7 days after rain was simulated using Hydrus-1D.The simulated results were close to the actual measured values.The error range is within the allowable range.It shows that the model selected by simulation is reasonable and the simulation parameters are more accurate.It also shows that in the case of mastering the physical properties of field soil,water movement parameters and meteorological data,the software can be used to simulate the field water movement situation more reasonably,and then the field water situation can be reasonably predicted.