氮肥施用量对新疆棉花产量及植株和土壤中硝态氮含量的影响

2000~2004年,在新疆的新和县和尉犁县,采用田间随机区组试验研究了不同土壤、栽培和灌溉条件下,氮肥施用量对不同棉花品种产量、植株中NO3-N含量及棉田土壤中NO3-N含量与分布的影响。结果表明,施用不同量氮肥可使棉花增产2%~73.8%,在新和县的栽培和土壤条件下,氮肥对棉花产量的影响不显著(F2000=0.72);在尉犁县的栽培和土壤条件下,无论采用常规灌溉还是滴灌方式,氮肥对棉花产量的影响均达到了显著水平(F2001=8.20**,F2002=2.91*,F2003=10.75**,F2004=17.97**);不同土壤、栽培和灌溉条件下,不同棉花品种的氮肥推荐用量各不相同,但报酬递减的趋势基本一致,棉花产量与氮肥施用量之间可以用二次曲线进行拟合,施氮量过高棉花产量反而有下降的趋势;棉花盛蕾期与初花期植株中NO3-N含量与施氮量及棉花产量表现出很好的相关性,因此可以将其作为棉花氮素营养快速诊断的参考指标;虽然不同灌溉方式对土壤中NO3-N残留的影响有所不同,但高氮肥施用量会使棉田土壤中聚集较高含量的NO3-N,增大了氮素淋失的风险,并成为潜在的环境污染源。

Effects of N rate on cotton yield and nitrate-N concentration in plant tissue and soil

The random field tests from 2000 to 2004 in Xinhe county and Yuli county in Xinjiang were carried out to evaluate the effects of different amounts of nitrogen fertilizers on cotton yield of different varieties,nitrate-N concentration in plant tissue and soil under different types of soil,different patterns of cultivation or irrigation.The results were as follows:applying nitrogen fertilizer increased cotton yield by(2%-)73.8%.Effects of nitrogen fertilizer on cotton were unsignificant at Xinhe county(F_(2000)=0.72) with local cultivation mode and soil condition,but were significant at Yuli in spite of tradition or drip irrigation system(F_(2001)=8.20~(**),F_(2002)=2.91~*,F_(2003)=10.75~(**),F_(2004)=17.97~(**)).The optimum N rates of different varieties were not equal under different soil conditions,different cultivation patterns and different irrigation modes,but the trends of degression of payment were consistent.Cotton yields were quadratic correlated with N rate,and Cotton yields declined with excessive N rates.The nitrate-N concentration in plant tissue during budding period or flowering period was prominently correlated to nitrogen fertilizer amount and cotton yield,it showed that nitrate-N concentration in plant tissue should be an referrence index for the quick diagnose of cotton nutrition.Furthermore,accumulation of nitrate in soil was affected by irrigation mode,and a great deal of nitrate remained in cotton field with excessive N rate which enhanced the risk of nitrate leaching,and became a potential source of environment pollution.