稻田氮排放规律对氮肥调控的响应

Response of Nitrogen Emission Regularity in Paddy Fields to the Nitrogen Fertilizer Regulation

为明确稻田氮排放规律对氮肥调控的响应,优化氮肥调控措施,设置不施氮处理(N0)对照组、低氮(N1,90 kg·hm^(-2))、正常施氮(N2,150 kg·hm^(-2))和过量施氮(N3,270 kg·hm^(-2))4个不同氮水平处理,于2021—2022年进行为期两年的大田试验。研究结果表明:增施氮肥后表观氮排放较对照增加140.8%~728.3%,显著高于植株吸氮量(61.1%~139.6%)和残留无机氮(17.5%~37.7%);气体、水体、淋溶氮排放量在N3条件下分别较对照增加915.0%,194.7%和379.8%,气体氮排放量增幅显著高于其他排放途径;土壤NO_(3)^(-)-N淋溶排放比例在3个施氮处理间变化量为0.31%~1.68%,差异未达显著水平,土壤NH_(4)^(+)-N淋溶排放比例则在增施氮肥后显著增加了17.1%~44.7%。以上结果表明:与植株吸氮量和残留无机氮相比,表观氮排放对氮肥调控的响应更敏感;与水体氮排放和淋溶氮排放相比,气体氮排放对氮肥调控响应更敏感;与晒田排水氮排放相比,降雨径流氮排放对氮肥调控更为敏感;与土壤NO_(3)^(-)-N淋溶相比,土壤NH_(4)^(+)-N淋溶对氮肥调控响应更敏感。

In this study,a field experiment was conducted over a period of two years from 2021 to 2022 in order to clarify the response of nitrogen emission regularity in paddy field to the nitrogen fertilizer regulation.The experiment consisted of four treatments:a control group(NO)without nitrogen application,and three treatment groups with varying levels of nitrogen,i.e.low(N1,90 kg·hm^(-2)),normal(N2,150 kg·hm^(-2)),and excessive(N3,270 kg·hm^(-2))nitrogen applications.The research findings demonstrated that the apparent nitrogen emissions increased significantly,ranging from 140.8%to 728.3%,after the application of nitrogen fertilizer.These emissions were substantially higher than the nitrogen uptake by plants(61.1%~139.6%)and residual inorganic nitrogen(17.5%~37.7%).Furthermore,under the N3 condition,the emissions of nitrogen through gas,water,and leaching exhibited considerable increases of 915.0%,194.7%,and 379.8%,respectively.Notably,the increase in gas nitrogen emissions surpassed that of other emission pathways.The variation in the leaching proportion of soil NO_(3)^(-)-N among the three nitrogen application treatments ranged from 0.31%to 1.68%,but the differences were not statistically significant.In contrast,the leaching proportion of soil NH_(4)^(+)-N significantly increased by 17.1%to 44.7%after nitrogen fertilization.The aforementioned findings demonstrated that apparent nitrogen emissions exhibited greater sensitivity to the nitrogen fertilizer regulation when compared to nitrogen uptake by plants and residual inorganic nitrogen.Gas nitrogen emissions,in terms of the response to the nitrogen fertilizer regulation,displayed higher sensitivity than nitrogen emissions in water and leaching.Furthermore,rainfall runoff nitrogen emissions were more responsive to the nitrogen fertilizer regulation than nitrogen emissions in sundry field and drainage.Soil NH_(4)^(+)-N leaching demonstrated a higher sensitivity to the nitrogen fertilizer regulation than soil NO_(3)^(-)-N leaching.