Response of Nitrogen Emission Regularity in Paddy Fields to the Nitrogen Fertilizer Regulation
In this study,a field experiment was conducted over a period of two years from 2021 to 2022 in or-der to clarify the response of nitrogen emission regularity in paddy field to the nitrogen fertilizer regulation.The ex-periment consisted of four treatments:a control group(N0)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 leac-hing 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 statisti-cally significant.In contrast,the leaching proportion of soil NH4+-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 ni-trogen.Gas nitrogen emissions,in terms of the response to the nitrogen fertilizer regulation,displayed higher sensi-tivity than nitrogen emissions in water and leaching.Furthermore,rainfall runoff nitrogen emissions were more re-sponsive to the nitrogen fertilizer regulation than nitrogen emissions in sundry field and drainage.Soil NH4+-N leac-hing demonstrated a higher sensitivity to the nitrogen fertilizer regulation than soil NO-3-N leaching.
paddy field emissionsammonia volatilizationnitrogen leachingnitrogen application rate
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