Effect Of Sugarcane Biochar On Primary Nitrogen Transformation Rate In Calcareous Soil And Latosol Soil

Calcareous soil(C)formed by limestone and latosol soil(L)formed by basalt are soils with different pH and salinity,but both soils have poor fertility retention.The effect of biochar on soil is related to soil properties and soil action time.Understanding the primary transformation rate of soil nitrogen,which is closely related to soil properties,is of great significance for further understanding the law of nitrogen transformation and evaluating its agronomic and environmental effects.In this paper,calcareous soils and latosol soil in hot regions were selected as test materials.Two levels of biomass carbon were set in each soil.Soils with biochar added in short-term and long-term cultivation were used to study the effect of biomass carbon on soil nitrogen transformation by 15N isotope labeling method combined with MCMC nitrogen transformation model.Soil physical and chemical properties data and micro-level data were used to study the effect of biomass carbon on soil nitrogen transformation.The correlation between biological data and primary nitrogen conversion rate was analyzed to explore the effect of biochar on soil nitrogen transformation.The main results are as follows:1、The addition of biochar to calcareous soils and latosol soil could rapidly increase soil pH and organic carbon content,but had no significant effect on total nitrogen content.Long-term action of biochar on calcareous soil can significantly increase soil pH,organic carbon,total phosphorus,available phosphorus and available potassium,and then affect soil ammonia oxidation archaea,fungi/bacteria ratio,PLFA of anaerobic bacteria and fungi.Long-term action of biochar on latosol resulted in significant increases in soil pH,organic carbon and available potassium,which affected total PLFA,PLFA of bacteria,fungi,Gram-positive bacteria,Gram-negative bacteria,actinomycetes and fungi/bacteria ratio.2、The short-term effect of biochar on calcareous soils was observed.High biomass charcoal application significantly increased the adsorption rate of NH4+.It may be due to the adsorption of biochar,which reduced the substrate of autotrophic nitrification and the autotrophic nitrification was reduced by 23.5%.The short-term effect of biomass charcoal on latosol soil increased NH4Assimilation rate,probably due to the increase of C/N in biomass charcoal,which contributed to NH4+ assimilation,reduced the substrate of autotrophic nitrification and reduced autotrophic nitrification.3、Biochar acts on calcareous soils for a long time,reducing AOA copy number and inhibiting autotrophic nitrification.High C/N biomass charcoal can increase NO3-fixation,thereby reducing the leaching risk of NO3" in calcareous soils.Biochar acts on latosol soil for a long time to increase the total mineralization rate and nitrification rate of latosol soil.Biochar results in the increase of AOA and AOB copies in soil,accelerates the consumption of NH4+ and mineral rate,and promotes nitrification.4、The difference in response of physical and chemical properties and microbiological properties of calcareous soils and Latosols to biochar leads to the difference in primary transformation rates of soil nitrogen.