Influence Mechanism Of Soil Physicochemical Property And Yield And Nitrogen Efficiency Of Spring Corn By Combined Application Of Biochar With Nitrogen Fertilizer

In this paper,the effects of the combined application of biochar and nitrogen fertilizer on the physicochemical property of the surface soil and the yield and nitrogen efficiency of spring corn in the east and west of Inner Mongolia were studied,and the physiological mechanism of obtaining the yield of spring corn sustainability and stably with high nitrogen efficiency by improving soil conditions was clarified.The main research results were as follows:(1)Two years of field trials have shown that,compared with individual biochar and nitrogen fertilizer application,the combined application biochar with nitrogen fertilizer improved the structure and water retention of surface soil to a greater extent.By optimizing the soil water,heat and gas conditions,the deviation values R of 0-10 cm,10-20 cm and 20-40 cm layers of the test soil were reduced by 28.16%,37.30%and 19.50%compared with the ideal soil.At the same time,biochar and nitrogen combination increased soil carbon and nitrogen reserves,promoted the microbial quantity,microbial quotient and soil enzyme activity in each layer of soil.The combined application biochar with nitrogen fertilizer promoted the accumulation of dry matter and nitrogen of spring corn through the improvement of soil conditions,achieved the synergistic improvement of yield and nitrogen efficiency.(2)Taken the surface soil of two test sites in the east and west of Inner Mongolia as the research object,the combined application different amounts of biochar with nitrogen fertilizer was designed.The results showed thatthe two nitrogen application amounts(N150 and N300)and the appropriate amount of biochar(C8 and C16)make the soil structure the most reasonable and the water holding capacity the greatest.The bulk density of 0-10 cm and 10～20 cm soil layers were around 1.26 g/cm3 and 1.29 g/cm3 and the porosity were around 52%and 51%respectively,the soil moisture retention performance was the largest.By optimizing the proportion of solid phase,liquid phase and gas phase,the reasonable biochar combined with nitrogen fertilizer could make the tested soil closer to the ideal soil structure and improve the soil physical properties.(3)With the addition of biochar and nitrogen,the soil organic carbon,total nitrogen and carbon nitrogen ratio of every soil layer increased significantly(P<0.01),reaching the maximum value in C24 combined application of N150 and N300.At the same time,high application of biochar and all kinds of nitrogen fertilizer could significantly increase dissolved organic carbon,available nitrogen and inorganic nitrogen(P<0.05).The promotion effect on the 0～20 cm soil layer was greater than that of the 20～40 cm soil layer.(4)Appropriate amount of biochar combined with nitrogen fertilizer significantly increased soil microbial biomass and soil enzyme activity.Microbial biomass carbon,microbial biomass nitrogen,microbial quotient,invertase,urease,catalase,and total enzyme activity in the three soil layers increased first and then decreased with the increase of biochar nitrogen application amount,and the combined biochar treatments of C8 and C16 with nitrogen treatment of N150 maintained high biological activity.According to the overall analysis of soil biochemical property,soil microbiological quantity increased first and then decreased with the increase of soil carbon and nitrogen ratio,and reached the peak at about 12.(5)Biochar and nitrogen fertilizer with different proportions mainly achieved synergistic increase of dry matter and nitrogen content ofgrain by increasing the accumulation of dry matter and nitrogen after flowering,with different amount of biochar with N150 as the maximum in all treatments.Biochar andnitrogen combination could significantly increase the yield of spring corn.However,the nitrogen efficiency of N150 was significantly greater than that of N300,and that of C8 and C16 was significantly greater than that of C24.In terms of comprehensive yield and nitrogen efficiency,appropriate biochar(C8)and nitrogen(N150)combination was the most effective in synergistic increase of yield and nitrogen efficiency.Based on the correlation analysis of yield and soil structure,the combined application of biochar and nitrogen fertilizer regulate the soil properties of 0～20 cm soil layer to obtain high yield and high efficiency of spring maize.