等氮量有机替代对水稻田面水氮素动态变化特征研究

Study on Dynamic Characteristics of Nitrogen in Surface Water of Paddy Field by Equal Nitrogen Organic Substitution

为了防控高原湖泊流域稻田氮素径流流失,保护受纳水体生态环境。在洱海流域水旱轮作种植模式下,设置不施肥(CK)、单施化肥(NPK)、有机无机配施(NPKS)、有机肥全量替代(SS)4个等氮量有机替代处理,研究水稻田面水氮素浓度的动态变化特征,探讨有机肥替代化肥施用对田面水氮素流失的影响。试验结果表明:基肥施用后田面水NH_(4)^(+)-N、NO_(3)^(-)-N、Org-N和TN浓度迅速升高,在3~7 d内达到峰值,施肥后7 d是防止田面水氮素大量流失的关键风险期。等氮量有机替代种植,田面水中NH_(4)^(+)-N/TN浓度占比为39.01%~54.01%,NO_(3)^(-)-N/TN浓度占比为11.33%~21.62%,Org-N/TN浓度占比为33.85%~41.94%。化肥氮施用增加田面水NH_(4)^(+)-N/TN浓度占比,有机肥施用增加田面水NO_(3)^(-)-N/TN和Org-N/TN浓度占比。等氮量有机替代对田面水氮素浓度的响应随施肥天数的增加而减弱,田面水NH_(4)^(+)-N、NO_(3)^(-)-N、Org-N、TN的浓度变化呈一元二次多项式下降,基肥施氮后35~40 d田面水氮素浓度趋于稳定低水平。在3种有机替代种植方式中,NPKS处理可降低田面水氮素浓度,降低稻田氮素流失风险。

To prevent and control the loss of nitrogen runoff in paddy fields in plateau lake basins and protect the ecological environment of receiving water bodies,under the paddy-upland rotation planting pattern in Erhai Lake Basin,four equal nitrogen organic substitution treatments were set up,including no fertilization(CK),single application of chemical fertilizer(NPK),combined application of organic and inorganic fertilizers(NPKS),and total replacement of organic fertilizer(SS).The dynamic changes of nitrogen concentration in surface water of paddy field were studied,and the effect of organic fertilizer instead of chemical fertilizer on nitrogen loss in surface water was discussed.The results showed that the concentrations of NH_(4)^(+)-N,NO_(3)^(-)-N,Org-N and TN in surface water increased rapidly after the application of base fertilizer,and reached the peak within 3-7 days.7 days after fertilization was the key risk period to prevent the loss of nitrogen in surface water.The proportion of NH_(4)^(+)-N/TN concentration in surface water was 39.01%-54.01%,the proportion of NO_(3)^(-)-N/TN concentration was 11.33%-21.62%,and the proportion of Org-N/TN concentration was 33.85%-41.94%.The application of chemical fertilizer nitrogen increased the proportion of NH_(4)^(+)-N/TN concentration in surface water,and the application of organic fertilizer increased the proportion of NO_(3)^(-)-N/TN and Org-N/TN concentration in surface water.The response of organic substitution of equal nitrogen amount to nitrogen concentration in surface water decreased with the increase of fertilization days.The concentration changes of NH_(4)^(+)-N,NO_(3)^(-)-N,Org-N and TN in surface water decreased in a quadratic polynomial,and the nitrogen concentration in surface water tended to be stable at a low level after 35-40 days of nitrogen application.Among the three organic substitution planting methods,NPKS treatment could reduce the nitrogen concentration in surface water and reduce the risk of nitrogen loss in paddy fields.