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This article in AJ

  1. Vol. 98 No. 1, p. 55-62
     
    Received: Jan 12, 2005


    * Corresponding author(s): cr1lobel@uco.es
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doi:10.2134/agronj2005.0017

Fertilizer Nitrogen Efficiency in Durum Wheat under Rainfed Mediterranean Conditions: Effect of Split Application

  1. Luis López-Bellido *a,
  2. Rafael J. López-Bellidob and
  3. Francisco J. López-Bellidoc
  1. a Dep. de Ciencias y Recursos Agrícolas y Forestales, Univ. of Córdoba, Campus de Rabanales, Edificio C-4 “Celestino Mutis,” Ctra. Madrid km 396, 14071 Córdoba, Spain
    b Dep. de Ciencias Agroforestales, Univ. of Huelva, Spain
    c Dep. de Producción Vegetal y Tecnología Agraria, Univ. of Castilla La Mancha, Spain

Abstract

Efficient N fertilizer management is critical for the economic production of wheat and the long-term protection of environmental quality. A 3-yr field experiment on a rainfed Vertisol was designed to study the effects of N fertilizer timing on the efficiency of N in durum wheat (Triticum turgidum L. var. durum Desf.). A single rate of 150 kg N ha−1 was used with different fractions being applied at planting, tillering, and stem elongation. A 15N experiment was also conducted within the main experiment area, with microplots, to quantify N uptake from fertilizer and soil. Mean wheat recovery of N fertilizer ranged from 12.7% when applied at sowing to 41.6% when applied as a topdressing at the beginning of stem elongation. The mean annual contribution of soil residual N and mineralization was 167 kg N ha−1, representing a considerable proportion of total wheat N uptake—ranging from 80.4% when N fertilizer was applied in the fall to 56.3% when it was applied at stem elongation. This would account for the poor and inconsistent response of grain yield and N efficiency indices, and for the importance of soil N in Vertisols for predicting wheat N fertilizer requirements, due to the carryover effect. It is recommended that N fertilizer be applied mainly as a topdressing in durum wheat, between tillering and stem elongation, to enhance crop N use efficiency (NUE) and reduce losses through leaching and runoff.

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