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Reduced fertilizer rates enhanced nitrogen use efficiency and decreased nitrogen loading in paddy rice - wheat long-term rotational cropping in Chao Lake watershed, East China
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  • NEBIYOU Hadush,
  • Manqin Gan,
  • Peishi Liu,
  • Yu Huang ,
  • Hongjun Xu,
  • Ma Youhua
NEBIYOU Hadush
Anhui Agricultural University
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Manqin Gan
Anhui Agricultural University
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Peishi Liu
Anhui Agricultural University
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Yu Huang
Anhui Agricultural University
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Hongjun Xu
Anhui Province People's Government
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Ma Youhua
Anhui Agricultural University
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Abstract

Fertilizer application in excess of plant nitrogen requirements, leading to nitrogen use inefficiency has become main culprit of nitrogen surplus, posing nonpoint pollution threats. Chao Lake has been recipient of nitrogen loadings, mainly coming from the agroecosystem surrounding it. This study was conducted in Chao Lake watershed to assess nitrogen use efficiency, crop yield and nitrogen loading, using reduced and conventional fertilizer rates, based on ten years field monitoring and experiment. Paddy rice - wheat rotational tillage arranged in a completely randomized design using 30m2 treatment plots was employed to study hypothesis. Three indicators namely agronomic efficiency (kgkg-1), recovery efficiency (%) and partial factor productivity (kgkg-1) were considered for nitrogen use efficiency. For nitrogen loading, nitrogen loading (kg ha-1yr-1), nitrogen runoff loss ratio (%) and net nitrogen runoff loss ratio (%) were taken. Results revealed, empirical formula of an exponential model explains the relationship. Reduced fertilizer levels produced high nitrogen use efficiency, high economic yield and less nitrogen loading. Nitrogen use efficiency was in order of: reduced > high > conventional fertilization treatments, while it decreased in ten years (2008 -2018) across all treatments. Nitrogen loading increased in ten years, both for rice and wheat growing seasons. Runoff volume influenced nitrogen loading more than other environmental factors considered. Such strategies that further reduce fertilizer levels by accounting for excessive supplies are critically important to consolidate effective nitrogen management measures.

Peer review status:UNDER REVIEW

16 Oct 2020Submitted to Land Degradation & Development
16 Oct 2020Assigned to Editor
16 Oct 2020Submission Checks Completed
19 Oct 2020Reviewer(s) Assigned