江汉平原棉田地表径流氮磷养分流失规律

2008年和2009年连续2年设置田间试验,采用径流池收集对照与农民习惯施肥2种处理的地表径流,研究江汉平原区棉花种植模式下地表径流产生规律,氮、磷流失规律,肥料氮、磷流失系数及其影响因素。结果表明,江汉平原地区地表径流主要发生在3-8月降雨比较集中的时期,径流产生量随产流时段降雨量的增加而增加,年降雨产流系数平均为26.0%。2008年和2009年农民习惯施肥处理的氮流失量分别是36.14,89.52kg/hm2,磷流失量分别是0.42,10.07kg/hm2,氮、磷流失量的年际间差异较大。氮流失的主要形态是硝态氮,其2008年和2009年的流失量分别占氮流失量的92.8%和64.2%,其次是颗粒态氮,以铵态氮形式流失的只是极小一部分;磷主要以颗粒态磷形式流失,其次是可溶性磷,尤其在产流时段降雨量大的年份,颗粒态磷的流失量占到总磷的90%以上。综合2008-2009年的结果,肥料氮、磷的流失率分别为5.4%和3.1%。氮、磷的流失量主要受施肥、产流时段降雨量和作物覆盖率影响,施肥导致氮、磷养分流失量增加,产流时段降雨量越大,作物覆盖率越低,则氮、磷养分流失量越大。

Regular Pattern of Nitrogen and Phosphorus Runoff Losses from Cotton Field in Jianghan Plain

In 2008 and 2009,experimental plots under two different kinds of treatment(control and farmer’s fertilizer practice) were conducted,and the runoff water in each plot were collected and tested,to investigate the law of runoff,the regular pattern and the influential factors of nitrogen and phosphorus losses,and to study the coefficient of fertilizer losses in Jianghan Plain.The results showed that the runoff events usually occurred in raining season from March to August,and the runoff volume increased with the rise of rainfall in the runoff producing period.The coefficient of runoff averaged at 26.0%.In the farmer’s fertilizer practice treatment,the nitrogen losses from cotton field was 36.14 kg/hm2 in 2008 and 89.52 kg/hm2 in 2009,the phosphorus losses in these two years was 0.42 kg/hm2 and 10.07 kg/hm2,both of which were considerable different between years.The nitrate nitrogen was the most main way of nitrogen losses,which accounted for 92.8% and 64.2% of the nitrogen losses in those two years,next came the particle nitrogen,the amount of ammonium nitrogen losses was very few.The predominant losing phosphorus form was the particle phosphorus,next came the dissolved phosphorus.The amount of particle phosphorus losses increased significantly in the year with larger rainfall during the runoff production period,which accounted for more than 90% of the phosphorus losses.The coefficients of nitrogen and phosphorus losses was respectively 5.4% and 3.1%,based on the results in the two consecutive years.It was found that fertilizer,rainfall in runoff producing stage and crop cover degree were three main factors influencing nitrogen and phosphorus losses.The amount of nitrogen and phosphorus losses was improved by fertilization,and also increased with the increasing rain capacity during the runoff producing period,and the decreased crop cover degree.