Pedosphere 30(6): 759--768, 2020
ISSN 1002-0160/CN 32-1315/P
©2020 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Optimization of nitrogen fertilizer rate under integrated rice management in a hilly area of Southwest China
Yujiao DONG1, Jiang YUAN1, Guangbin ZHANG2, Jing MA2, Padilla HILARIO3, Xuejun LIU4, Shihua LU1
1Soil and Fertilizer Research Institute/Key Laboratory of Agricultural Environment in Southwest Mountain Areas of Ministry of Agriculture and Rural Affairs, Sichuan Academy of Agricultural Sciences, Chengdu 610066(China)
2State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008(China)
3Kadoorie Farm and Botanic Garden, Hong Kong 999077(China)
4Key Laboratory of Plant-Soil Interactions of Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193(China)
      China has the world's highest nitrogen (N) application rate, and the lowest N use efficiency (NUE). With the crop yield increasing, serious N pollution is also caused. An in-situ field experiment (2011-2015) was conducted to examine the effects of three N levels, 0 (i.e., no fertilizer N addition to soil), 120, and 180 kg N ha-1, using integrated rice management (IRM). We investigated rice yield, aboveground N uptake, and soil surface N budget in a hilly region of Southwest China. Compared to traditional rice management (TRM), IRM integrated raised beds, plastic mulch, furrow irrigation, and triangular transplanting, which significantly improved rice grain yield, straw biomass, aboveground N uptake, and NUE. Integrated rice management significantly improved 15N recovery efficiency (by 10%) and significantly reduced the ratio of potential 15N loss (by 8%-12%). Among all treatments, the 120 kg N ha-1 level under IRM achieved the highest 15N recovery efficiency (32%) and 15N residual efficiency (29%), with the lowest 15N loss ratio (39%). After rice harvest, the residual N fertilizer did not achieve a full replenishment of soil N consumption, as the replenishing effect was insufficient (ranging from -31 to -49 kg N ha-1). Furthermore, soil surface N budget showed a surplus (69-146 kg N ha-1) under all treatments, and the N surplus was lower under IRM than TRM. These results indicate IRM as a reliable and stable method for high rice yield and high NUE, while exerting a minor risk of N loss. In the hilly area of Southwest China, the optimized N fertilizer application rate under IRM was found to be 100-150 kg N ha-1.
Key Words:  N input,N output,15N recovery efficiency,N surplus,N use efficiency,plastic mulch,soil surface N budget
Citation: Dong Y J, Yuan J, Zhang G B, Ma J, Hilario P, Liu X J, Lu S H. 2020. Optimization of nitrogen fertilizer rate under integrated rice management in a hilly area of Southwest China. Pedosphere. 30(6):759-768.
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