Ammonia Volatilization from Soil as Affected by Long-term Application of Organic Manure and Chemical Fertilizers During Wheat Growing Season

Ammonia(NH3)volatilization is one of the major losses of applied nitrogen fertilizers,which not only results in a loss of economy,but also poses a risk to the environmental ecosystem. The rate of ammonia volatilization following fertilizer application is strongly affected by many factors such as soil properties,temperature as well as type,application time and mode of nitrogen fertilizers. To find optimal management practices for increasing nitrogen use efficiency,a long-term experiment was established in 1989 including seven treatments. i.e. organic manure(OM),half organic manure plus half chemical N fertilizer(1/2OM),NPK fertilize(rNPK),NK fertilizer(NK),NP fertilizer(NP),PK fertilize(rPK)and contro(lCK),six treatments of which were used to monitor ammonia volatilization during the wheat growing season using a continuous air flow enclosure method in the North China plain. The flux of ammonia volatilization was dramatically influenced by fertilizer type and their combination. The highest cumulative amount of ammonia volatilization in treatments NK and OM was 17.89 and 15.70 kg N. hm-2,respectively,as urea was applied at a rate of 150 kg N.hm-2,which accounted for 10.47%～11.93% of the N applied and was significantly higher than the values in treatments NPK,NK and 1/2OM. The flux of ammonia volatilization was significantly positively correlated with air temperature. And irrigation following basal fertilization greatly reduced ammonia volatilization. Our study indicates that NPK balanced application and combination application of organic manure and chemical N fertilizer could lower ammonia volatilization.