Exploring the connection between agricultural nitrogen input and agricultural non-point source pollution risk:a case study of Henan Province
The purpose of this study is to mitigate non-point source pollution risk and enhance nitrogen use efficiency in fertilizer applications.Employing the principles of soil nitrogen balance,this research analyzed nitrogen fertilizer application across 18 cities in Henan Province using list analysis and sewage discharge coefficient methods.The study quantitatively assessed soil nitrogen surplus,theoretical nitrogen application rates,and monitored nitrogen application rates.The findings revealed that farmland across 18 cities in Henan Province generally exhibited a surplus in soil nitrogen content,with an average nitrogen surplus of 255 kg/hm2.The low nitrogen production efficiency and excessive fertilization emerged as the primary contributors to agricultural non-point source pollution.Moreover,grain production and efficiency in Henan Province decreased from 3.793 × 106 t to 2.553 × 106 t.The average nitrogen application load decreased from 455 kg/hm2 to 319 kg/hm2,while the average nitrogen production efficiency in Henan Province increased from 14.3 kg/kg to 22.3 kg/kg.These outcomes effectively enhanced nitrogen fertilizer production efficiency and reduced the risk of agricultural non-point source pollution.Given the substantial crop consumption and planting structure,farmland exhibits minimal soil nitrogen excess,resulting in a low risk of agricultural non-point source pollution.Conversely,in regions like Jiyuan and Sanmenxia with low nitrogen application levels,the surplus of soil nitrogen in farmland is comparatively significant,leading to a higher risk of agricultural non-point source pollution.This risk is further amplified by factors such as topography,soil conditions,and agricultural practices.Hence,the greater the nitrogen application rate,the higher the risk of agricultural non-point source pollution.This underscores the need to avoid blindly pursuing"nitrogen reduction"in agricultural production.Instead,the focus should be on meeting the actual requirements of agricultural production and achieving increased yields.
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