南疆棉花施氮量及氮素平衡分析

2002~2003年对塔里木盆地南缘的策勒县和北缘的尉犁县农户的棉田施氮现状进行了实地调查。结果表明:区内农户间施氮量差异较大,平均施氮总量达426~430 kg/hm2,过量施氮很普遍,分别有39.5%(策勒)和72.8%(尉犁)的农户过量施氮,施氮量与产量已经不相关,增加施氮已经不能增产,生产中应该遏止施氮量增加趋势,适当减少高施氮量。另外,还有6.2%~7.9%的棉田施氮量不足,这部分农户应该提高施氮量;策勒县偏重追施氮肥,单次追肥施氮量偏大,基追比为1∶5.12。尉犁县偏重基施氮肥,平均化肥基施量达171~273 kg/hm2,基追比为1∶0.48~1∶0.78,应通过减少基肥施氮量和单次追氮量,实现少量多次的氮肥施用策略,提高氮的利用效率;养分平衡计算结果表明,氮素盈余量达到87~248 kg/hm2;策勒和尉犁两个县总体上0~90 cm土壤N残留不高,只有10%~32%的棉田超过100 kg/hm2。

Investigation of N fertilization practice and N equilibrium analysis in cotton fields in south Xinjiang

Tarim basin of south Xinjiang is one of the most important cotton planting area in China,but the information about N fertilization practice in the cotton fields is lacking.In order to make clear the situation of N fertilization,an investigation was conducted in Cele and Yuli County of Xinjiang Uygur Autonomous Region in 2002~2003.The results show that the amounts of N fertilizer applied to cotton fields were much discrepant among different farmers.The average N fertilization rate was 426~430 kg/hm~2,and the phenomena of excessive N fertilizer application were rather popular.The proportion of farmers with excessive N fertilizer application was 39.5% in Cele and 72.8% in Yuli,whereas there were 6.2%~7.9% of farmers with deficient N fertilizer.The farmers in Cele utilize more N fertilizer as top dressing,while the farmers in Yuli utilize more N fertilizer as basal fertilization.There was no relationship between the yields of seed cotton and total N fertilizer or mineral N fertilizer in both Cele and Yuli.The results of N equilibrium analysis showed that the average amount of N surplus in Cele and Yuli was 87~248(kg/hm~2,) and the average residue N_(min) in 0~90 cm soil profile after harvest was mostly less than 100(kg/hm~2.)