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This article in AJ

  1. Vol. 104 No. 2, p. 523-529
     
    Received: Aug 13, 2011


    * Corresponding author(s): zhenlingcui@163.com
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doi:10.2134/agronj2011.0258

Critical Nitrogen Dilution Curve for Optimizing Nitrogen Management of Winter Wheat Production in the North China Plain

  1. Shanchao Yuea,
  2. Qingfeng Menga,
  3. Rongfang Zhaob,
  4. Fei Lic,
  5. Xinping Chena,
  6. Fusuo Zhanga and
  7. Zhenling Cui *a
  1. a Dep. of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
    b Dep. of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, and College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
    c Dep. of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, and College of Ecology and Environmental Science, Inner Mongolia Agricultural University, Hohhot 010019, China

Abstract

Investigating critical N concentration, that is, the minimum N concentration necessary to achieve maximum growth, provides insights into N nutrition and can serve as a guide to improving agricultural practices and regulations. Our objectives were to evaluate N dilution curves for deficient, optimal, and excess added N and to determine the critical N dilution curve for winter wheat (Triticum aestivum L.) in the North China Plain (NCP) based on 15 N fertilization experiments with three to six N fertilization rates. The N supplements significantly affected the N dilution curve, and increased N supply generally resulted in a greater N concentration. The critical N dilution curve for winter wheat was described by the equation nitrogen concentration (Nc) = 4.15 W–0.38 when aboveground biomass was between 1 and 10 Mg dry matter (DM) ha−1. When aboveground biomass was <1 Mg DM ha−1, the constant critical value Nc = 4.15% DM, which was independent of aboveground biomass. This curve was lower than that of winter wheat in France. This critical N dilution curve was validated through the nitrogen nutrition index (NNI) defined as the ratio between measured N concentration and critical Nc. The critical N dilution curve holds promise as an efficient tool for guiding N-fertilization practices and regulations for winter wheat production in the NCP.

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