Nitrogen Budget and Surface Water Nitrogen Load in a Chinese Watershed
Yongqiang Zhao1, 2, Lvbing Jiang1, Yuguo Wu1
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1College of Geography and Tourism, Zhengzhou Normal University, Zhengzhou 450044, China
2State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science,
Chinese Academy of Sciences, Nanjing, 210008, China
Online publish date: 2018-02-05
Publish date: 2018-03-12
Submission date: 2017-06-25
Final revision date: 2017-08-07
Acceptance date: 2017-08-10
Pol. J. Environ. Stud. 2018;27(3):1387–1394
To assess the impact of human activity on the nitrogen (N) cycle and evaluate the sources of N in surface water, the N budget for Laoguanhe River Watershed (LRW), a typical agricultural watershed and one of the upstream tributaries of Danjiangkou Reservoir in China, was developed by using measurement data on N fluxes and literature data on other parameters. Over the whole watershed, fertilizers, human and livestock excreta, atmospheric deposition, biotic fixation, N from crop residue used as fertilizer, and imported animal feeds contributed 65.7%, 20.7%, 6.1%, 5.6%, 1.7%, and 0.3%, respectively, to total N input (40,816.6 kg N km-2 year-1). N transported to water bodies, denitrification, harvesting crops, and ammonia volatilization contributed 32.0%, 25.2%, 23.0%, and 19.8% of total N output (21291.2 kg N km-2 year-1), respectively. The N budget for the LRW suggested that more than 50% of the N input was lost to the environment, and about 17% was discharged as riverine N, which indicated that agricultural and human activities in the watershed substantially impacted water quality, and so altered the N biogeochemistry process.