施氮量对稻季氨挥发特点与氮素利用的影响

 在砂土和黏土两种土壤类型上，研究了施氮量对田面水NH4+ N浓度、氨挥发损失量、水稻产量、氮肥利用效率和土壤剖面氮素含量的影响。施氮后田面水NH4+ N浓度和氨挥发量都随着施氮量的增加而增加，且在施氮后1~3 d达到峰值，黏土要低于砂土；氨挥发损失量为分蘖肥时期＞倒4叶穗肥期＞基肥时期＞倒2叶穗肥期；黏土上稻季氨挥发总损失量为10.49~87.06 kg/hm2，占施氮量的10.92％~21.76％；砂土上稻季氨挥发总损失量为11.32~102.43 kg/hm2，占施氮量的11.32％~25.61％；施氮后氨挥发峰值和田面水铵态氮峰值同步出现，以分蘖肥时期最大，两者比值范围为23.76％~3365％；随着施氮量的增加，水稻产量增加，氮素积累量也增加，而氮肥利用效率降低；黏土上的水稻产量和氮素积累量要略高于砂土上的；土壤氮素含量在土壤深度40~50 cm处最低，相应各层土壤氮素含量随着施氮量的增加而提高，黏土要高于砂土。从氨挥发损失的角度来看，当施氮量超过250 kg/hm2时，氨挥发损失总量将跃增; 而从水稻获得高产的角度来看，施氮量应为300 kg/hm2左右，因此，试验条件下水稻高产且环境安全的适宜施氮量为250~300 kg/hm2。

Effects of Nitrogen Application Rate on Ammonia Volatilization and Nitrogen Utilization in Rice Growing Season

In contrast experiments in sandy soil and clay soil,effects of nitrogen application rates on the concentration of NH4+-N in surface water,the loss of ammonia volatilization from paddy field,the production of rice,the nitrogen utilization efficiency and the nitrogen content in soil profile were studied.The concentration of NH4+-N in surface water and the amount of ammonia volatilization losses all increased as the nitrogen application rate increased,and peaked at 1-3 days after nitrogen application.The loss ...