不同施肥模式下夏玉米田间土壤氨挥发规律

利用通气法田间原位试验,研究了不同施肥模式对夏玉米田间土壤氨挥发的影响.结果表明:单施化肥与秸秆还田配施化肥处理的田间氨挥发速率日变化与白天田间土壤表层温度(简称地温)变化表现基本一致,呈现由低到高的"单峰"趋势.夏玉米田间氨挥发损失的高峰期主要发生在白天11:00～13:00.但持续时间较短,单施化肥与秸秆还田配施化肥处理均在氮肥施入当天田间氨挥发速率达最高值,此后迅速降低,氨挥发损失主要集中于前7d,累计氨挥发量占总量的88.57%～96.72%.与单施化肥相比,秸秆还田配施化肥可显著减少氨挥发损失4.06～8.25 kg · hm-2,氨挥发损失率降低0.37%～1.17%.夏玉米大喇叭口期后对氮素需求较多,较高的田间土壤持水量均可以削弱氨挥发损失.确定适宜的秸秆与氮肥配比量,适量增加大喇叭口期的氮肥追施量配合及时浇水,是提高氮肥利用效率的有效途径之一.

Law of field soil ammonia volatilization in summer maize under different fertilizer patterns

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.