Study on the influence of different fertilizer on ammonia volatilization in cropland soil of the Xichuan Reservoir Area

CHEN Xiaoshu; ZHAO Tongqian

doi:10.16186/j.cnki.1673-9787.2022100086

Abstract：Ammonia volatilized from farmland fertilizers is a significant source of atmospheric and aquatic nitro-gen in the Danjiangkou Reservoir,a key water source for the Middle Route of the South-to-North Water Diver-sion Project,posing a threat to the water quality and safety of the reservoir area.Objectives In order to study the influence of different fertilizer on ammonia volatilization in cropland soil of the reservoir area,Methods tak-ing the typical cropland soils in the Xichuan Reservoir Area as the research object,in situ field monitoring was conducted using a closed static chamber method during the summer and autumn of 2020 to evaluate ammonia volatilization from soil under various fertilization practices.The effects of different fertilizers on the rate and cumulative amount of ammonia volatilization were analyzed,and the seasonal differences were ex-amined.Results The results showed that:(1)Fertilizer applications significantly increased soil ammonia volatilization rates.Urea-treated soils showed the highest volatilization rate,peaking between the 4th and 6th day after application and fluctuating the longest.Compound fertilizers followed the rate,with peaks occurring between the 6th and 9th days.Organic fertilizer treatments had the lowest volatilization rates,nearly match-ing the soil's natural background levels.(2)There were notable differences in cumulative ammonia volatiliza-tion among the different fertilizers.Urea treatments had the highest cumulative volatilization,approximately 10 times that of the control(no fertilizer),while compound and organic fertilizer were about 3 times and 1 time,respectively.This indicated that organic fertilizer had the least impact on ammonia volatilization.(3)Ammonia volatilization rates exhibited significant seasonal differences,with higher rates in summer com-pared with that in autumn.Under the same fertilization conditions,it took more than twice as long for ammo-nia volatilization in autumn to return to baseline levels compared with that in summer,although the net cu-mulative volatilization was not significantly different(0.04～2.41 kg·hm-2).While seasonal factors had influ-ences on volatilization behavior,the total volatilization remained consistent.The daily and total ammonia volatilization rates in autumn were lower than that in summer,but their impact on soil and atmosphere was more prolonged.Conclusions Adjusting fertilization practices by increasing the use of organic fertilizers and reducing the use of urea could effectively decrease soil ammonia volatilization caused by fertilization.