Abstract: In situ experiments combining field lysimeters and venting method were used to study the influence of different fertilization strategies on nitrogen leaching loss and ammonia volatilization from soil during the growing season of summer maize.The major season of nitrogen leaching was rainy season during the growing season of summer maize,with strong intensity of rainfall in the Huanghuaihai region.Both irrigation and rainfall affected the volume of water leaching from soil in the field.The obtained results showed that the volume of water leaching was 63.4-97 L/ha in the period of summer maize growth,which had positive correlation with the amounts of irrigation water and rainfall.Compared with single nitrogen fertilizer,organic manure combined with nitrogen fertilizer facilitated water leaching from in field.Both nitrogen leaching and ammonia volatilization were the major nitrogen losing ways in dryland farming system. The accumulative total nitrogen leaching was obviously more than the accumulative total ammonia volatilization in the period of summer maize growth,and both increased concomitantly with nitrogen application rate.Compared with single nitrogen fertilizer,organic manure combined with nitrogen fertilizer significantly increased the accumulative total nitrogen leaching,and reduced the accumulative total ammonia volatilization.Overall,organic manure combined with nitrogen fertilizer markedly increased the accumulative total amount and rate of nitrogen loss in the period of summer maize growth.The density of NO3--N in water leaching had two peaks,while the density of NH4+-N increased first and then decreased.The results also indicated that increasing N application at the rapid growth stage can reduce N leaching and volatilization,and is an effective approach to increasing nitrogen use efficiency.