Influence Of Biochar Applicationon On NH₃ Volatilization From Paddy Soil

Ammonia?NH₃?volatilization is a major pathway of nitrogen loss from paddy fields,resulting in large nitrogen loss and severe environmental pollution.Returning rice straw directly into paddy fields is very popular in China which may support sustainability of the agriculture,however,it will considerably accelerate NH₃ volatilization.As a new environmentally friendly material,biochar is famous for its capacity in increasing nitrogen retention in soil,and might be a promising material for NH₃ volatilization control in paddy fields.Therefore,if we take rice straw-derived biochar?SC?instead of rice straw return into paddy field,might realize crops increasing,soil amendment,and NH₃ volatilization control,which makes great contributions to environment protection and food security.However,few studies have focused on the effects of biochar on NH₃ volatilization from the paddy ecosystem,which is generally waterlogged with high nitrogen input,up to date.In this study,a field experiment was conducted to examine the potential role of SC in NH₃ volatilization from paddy fields in comparison with the addition of rice straw,by analyzing rice growth,surface water,soil property.The main conclusions are summarized as follows:?1?In a field experiment,we compared the effect of rice straw and biochar application on rice growth and rice yield.Result showed that biochar amendment significant prompt rice growth and yield,compared with corresponded controls?p<0.05?.A further study showed that the promoting effect of biochar was enhanced with the increase of rice growth and biochar application dose.Compared to CK,high dose or low dose of biochar application increase 16.5%or 8.0%in rice yield,respectively,showed a significant better effect than rice straw amendment.?2?Through phosphoglycerol soaked sponges,we measured the NH₃ volatilization from paddy field with rice straw or biochar application.Results reflected that different from the stimulation of NH₃ volatilization with rice straw application,biochar amendment showed a well ability in NH₃ volatilization control.Biochar application can not only delay the appearance of the volatilization peak at BF stage and AF1 stage,but also reduce more than 20%of cumulative NH₃ volatilization.However,there was no significant difference of NH₃ volatilization between the two biochar application doses.?3?Based on the microbial molecular biology and microstructure analysis technology,and comprehensive analysis of surface water,soil,microorganisms,plants and other indicators,we found that the inhibited NH₃ volatilization with biochar application was mainly due to the reasons as follow:? The stability of biochar which could well avoid the stimulation of NH₃ volatilization by rice straw degradation;? The stimulation ammonium absorption into biochar by high porosity and surface acidic functional groups;? Promotion to ammonium oxidation which resulted from highly enriched to copy numbers of archeal and bacterial amoA genes in paddy soil.All of them made contributions to reduce available NH4+-N in surface water,and realize the NH₃ volatilization control.