不同施肥模式对早稻季农田氮磷径流流失的影响

为探究湖南双季稻区早稻季防控稻田氮、磷养分流失污染的施肥模式,通过田间试验,设置了不施氮磷肥处理(CK)和常规施肥(CF)、有机肥替代(OM)、控释肥减施(CRF)、绿肥还田(GM)4种施肥模式,研究了不同施肥模式对稻田氮、磷养分径流流失的影响。结果表明:相较于常规施肥模式,有机肥替代、绿肥还田和控释肥减施模式稻田总氮径流流失量分别减少了12.80%、16.62%、28.55%,各施肥处理早稻总氮素流失率大小表现为:常规施肥有机肥替代绿肥还田控释肥减施,氮素流失形态主要以可溶性氮为主,占流失总氮的80.48%~91.96%,可溶性氮中以铵态氮为主。控释肥减施和绿肥还田模式均能减少稻田磷素径流损失量,与常规施肥模式相比,总磷径流流失量分别减少了6.26%和28.30%;有机肥替代模式稻田总磷径流损失量较常规施肥模式增加26.33%;各施肥处理早稻总磷流失率表现为:有机肥替代常规施肥绿肥还田控释肥减施,磷素流失形态前期以颗粒态磷流失为主,后期以可溶态磷为主。在4种施肥模式中,控释肥减施和绿肥还田模式能降低稻田氮磷径流流失量,在南方双季稻区推广这两种施肥模式可有效防控农田氮、磷流失污染风险。

Effects of different fertilization models on runoff loss of nitrogen and phosphorus in early rice paddy fields

In order to explore the characteristics of nitrogen and phosphorus nutrient runoff loss in double-cropping paddy fields in Hunan Province, different fertilization models were conducted in the early rice season. Five modes, no nitrogen and phosphorus fertilizer treatment (CK), conventional fertilization(CF), replacement of organic manure(OM), reduced application of controlled-release fertilizer(CRF), and green manure return (GM) were applied, and the effects on loss of nitrogen and phosphorus nutrients were analyzed. The results showed that compared with the conventional fertilization mode, the total nitrogen runoff loss of the organic fertilizer replacement, green manure return and controlled-release fertilizer reduction mode was reduced by 12.80%, 16.62%, and 28.55%, the total nitrogen loss rate of early rice with each fertilizer treatment was as follows: conventional fertilization > organic fertilizer replacement > green manure return > reduced application of controlled release fertilizer. The main form of nitrogen loss was soluble nitrogen, accounting for 80.48%~91.96% of the total nitrogen loss. The main form of soluble nitrogen was ammonium nitrogen. Both the reduced application of controlled-release fertilizer and green manure return could reduce the loss of phosphorus runoff in paddy fields. Compared with the conventional fertilization model, the total phosphorus runoff loss model has been reduced by 6.26% and 28.30%, the total phosphorus runoff loss of organic fertilizer substitution mode increased by 26.33%. And the total phosphorus loss rate of early rice in each fertilization treatment was as follows: organic fertilizer replacement > conventional fertilization > green manure return > controlled-release fertilizer reduction application. The form of phosphorus loss was mainly particulate phosphorus loss in the early stage and soluble phosphorus in the latter. In short, among these fertilization modes, the controlled-release fertilizer reduced application mode could minimize the loss of nitrogen and phosphorus in paddy fields. Therefore, in the southern double cropping paddy fields, the controlled release fertilizer reduction mode should be widely recommended, which could effectively reduce the loss of nitrogen and phosphorus as well as preventing non-point source pollution.