Law of field soil ammonia volatilization in summer maize under different fertilizer patterns
不同施肥模式下夏玉米田间土壤氨挥发规律

In situ experiments combined with venting method were conducted to study the effects of different fertilization patterns on ammonia volatilization from soil in the growth season of summer maize. The results showed that the NH3 volatilization rate of treatment of single fertilizer and treatment of wheat straw plus fertilizer had one peak and it first increased and then decreased after application of fertilizer. This trend behaved accordant with the change of earth temperature during the daytime. Ammonia volatilization occurred primarily during the daytime and the peak volatilization appeared between 11:00-13:00 each day. The high speed of volatilization continued for only a short period. Whether treated with single fertilizer or with wheat straw plus fertilizer, the NH3 volatilization rate peaked, and then rapidly decreased. The accumulative ammonia volatilization of the first 7 days accounted for 88.57%~96.72%.Compared with single fertilizer, wheat straw plus fertilizer reduced the total rate of accumulative ammonia volatilization significantly, which was 4.06~8.25 kg?hm-2 less in treatment of wheat straw plus fertilizer, and its loss rate reduced 0.37%~1.17%. More N fertilizer was demanded after period of flare opening of summer maize, and high field water capacity could weaken loss of ammonia volatilization. The results also indicated that increasing rate of N fertilizer at the rapid growth stage and assuring the optimal proportion of wheat straw to N fertilzier could reduce NH3 volatilization and was an effective approach to increase nitrogen use efficiency.