Abstract: In order to understand the equilibrium process of soil nitrogen under the condition of alternate partial root-zone irrigation and fertilization and improve the nitrogen use efficiency, soil ammonia volatilization rate and volatilization amount of summer maize were measured with static-closed chambers. The results showed that after irrigation and fertilization at the jointing stage of summer maize, soil ammonia volatilization rate increased rapidly and reached a peak (1.68-3.97 kg/hm2×d) at the second day. Then the volatilization rate decreased and entered into a period of slow volatilization. After alternative irrigation and fertilization at the tasseling stage of summer maize, the volatilization rate of soil ammonia was in a state of fluctuation. The accumulation and loss rate of soil ammonia volatilization were much less at the jointing stage of summer maize than those at the tasseling stage. The amount of soil ammonia volatilization was the lowest at the irrigation quantity of 350 m3/hm2 and fertilization amount of 256.08 kg/hm2. Compared with conventional irrigation and fertilization techniques, alternate partial root-zone irrigation and fertilization can reduce soil ammonia volatilization amount obviously.