Biofertilizer Mitigating Soil Ammonia Volatilization And Its Ecological Efficiency

Biofertilizer is a new type of green and environmentally-friendly fertilizer in the sustainable development of modern agriculture.It has the effects of microbial inoculants and organic fertilizers,which is beneficial to increase soil nutrient content,promote crop growth and development,and decompose and convert nutrients.In order to verify the effect of biofertilizer on preventing and controlling ammonia volatilization in farmland soils,and to preliminary explore its microbial ecological mechanism,through the methods of greenhouse potted lettuce and field demonstrations,to explore the effects of biofertilizer and chemical fertilizers on soil ammonia volatilization,crop quality and yield,changes in soil microorganisms,and colonization effects of plant probiotics.And analyze the ammonia control mechanism of biofertilizer from the aspects of soil pH,nitrification,soil enzymes and genes involved in nitrogen cycle function.At the same time,the effects of the addition of biofertilizer on the structure and abundance of soil microbial communities were analyzed using high-throughput sequencing and Q-PCR technology.The results are as follows:（1）Effect of biofertilizer mitigating soil ammonia volatilization and promoting crop growth.After fertilization,ammonia volatilization quickly appeared in the soil and reached its peak,and then began to decline.Compared with the application of chemical fertilizers,the biofertilizer treatment reduces the ammonia volatilization of the soil by advancing the time when the ammonia volatilization rate of the soil reaches its peak.The effect of adding Bacillus amyloliquefaciens biofertilizer on ammonia control was better than that of adding Trichoderma viride biofertilizer,and it could reduce the ammonia volatilization of farmland soil by 79.48%⁸4.81%.The treatment with T.viride biofertilizer reduced the soil ammonia volatilization by 47.52%⁷9.12%.At the same time,B.amyloliquefaciens biofertilizer significantly improved the yield and quality of lettuce,compared with the control,the yield increased by 50.5%.（2）Study on the mechanism of biofertilizer reducing ammonia volatilization in farmland soil.The experiment analyzes the ammonia control mechanism of biofertilizer from three aspects:soil pH,nitrification and genes involved in nitrogen cycle function.First,during the peak of ammonia volatilization,the pH of the soil treated with biofertilizer instead of part or all of the chemical fertilizer decreased.The important factors affecting soil ammonia volatilization rate include soil pH.The higher the value,the faster the ammonia volatilization rate.Secondly,the application of biofertilizer promoted the conversion of NH₄⁺-N to NO₃^--N in the soil,and the concentration of NH₄⁺-N decreased,thereby reducing the ammonia volatilization.Finally,the application of biofertilizer increased the number of ammonia oxidizing flora in the soil,promoted the conversion of NH₄⁺-N to NO₃^--N,and reduced the ammonia volatilization.（3）Effect of biofertilizer on soil microbial community structure.Biofertilizer increased the diversity and richness of soil bacterial communities,and the community structure and bacterial composition were significantly different.Compared with chemical fertilizer treatment,the relative abundance of Bacillus and Nitrospira,which replaced part or all of the chemical fertilizer by B.amyloliquefaciens,was increased by47.0%⁶9.4%and 8.43%¹9.28%,respectively.It promotes soil nitrification and reduces soil ammonia volatilization.（4）Field demonstration application of chemical fertilizers and B.amyloliquefaciens biofertilizer mitigating soil ammonia volatilization.In the field demonstration application,by comparing four different fertilization treatments,it was confirmed to understand the effectiveness of B.amyloliquefaciens biofertilizer in reducing ammonia volatilization in alkaline farmland soil,and and revealed the potential ammonia control mechanism from three levels of soil enzymes,genes and microorganisms.First,the combined application of chemical fertilizers and B.amyloliquefaciens biofertilizer reduced the ammonia volatilization loss of soil by 68%,while increasing crop yields by 19%and nitrogen fertilizer utilization efficiency by19%.The second is that B.amyloliquefaciens biofertilizer slows the conversion of fertilizer nitrogen to NH₄⁺-N and enhances ammonia oxidation,thereby reducing the accumulation of NH₄⁺-N in soil and reducing ammonia volatilization.The third is that B.amyloliquefaciens has good colonization and survival ability when it is loaded on organic fertilizer and applied to soil.Finally,it was verified that the c ombined application of chemical fertilizer and B.amyloliquefaciens biofertilizer is the best strategy to reduce agricultural ammonia emissions and increase crop yield.