The results of ammonia volatilization measured with micrometeorological(gradient diffusion) method in the field cropping with winter wheat and summer maize was reported.Under the production condition at the North Plain of China,the loss of ammonia (N)after fertilizer application ranged from 18.9 to 63.5 kg·hm -2 ,9.9% to 37.0% of the applied N.Ammonia volatilization occurred mainly during the daytime and the peak volatilization appeared between 12:00-16:00 pm each day.The ammonia volatilization pattern ...