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Agronomy Journal Abstract -

Long-Term Tillage, Crop Rotation, and Nitrogen Fertilizer Effects on Wheat Yield under Rainfed Mediterranean Conditions


This article in AJ

  1. Vol. 88 No. 5, p. 783-791
    Received: Aug 7, 1995

    * Corresponding author(s): crllobel@uco.es
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  1. L. López-Bellido ,
  2. M. Fuentes,
  3. J. E. Castillo,
  4. F. J. López-Garrido and
  5. E. J. Fernández
  1. D ep. de Producción Vegetal y Tecnología Agraria, Univ. of Castilla-La Mancha, 13071 Ciudad Real, Spain
    D ep. de Biología Vegetal, Producción Vegetal y Ecología, Univ. of Almería, 04120 Almeria, Spain



The combined long-term effects of tillage method and crop rotation on crop yield have not been studied in rainfed systems under Mediterranean climates. A field study was conducted from 1988 to 1994 to determine the effects of tillage (TILL), crop rotation (ROT) N fertilizer on wheat (Triticura aestivum L.) yield in a rainfed Mediterranean region. Tillage treatments include no tillage (NT) and conventional tillage (CT). Crop rotations were wheat-sunflower (Helianthus annuus L.) (WS), wheat-chickpea (Cicer arietinum L.) OVCP), wheatfababean (Vicia faba L.) OVFB), wheat-fallow (WF), and continuous wheat (CW), with fertilizer rates of 50, 100,and 150 kg N ha−1. A split-split plot design with four replications was used. Differences in rainfall during the growing season had a marked effect on wheat yield. Amount of rainfall during the vegetative period for wheat (November-February) was highly correlated with yield because of the high water-retention capacity of Vertisols (Typic Haploxerert). In dry years, wheat yield was greater under NT than under CT; the opposite was true in wet years. The TILL ✕ ROT interaction was also significant in the drought years; the wheat yield under NT was greater for CW and the WFB and WF rotations than under CT. Wheat yields ranked by crop rotation were: WFB > WF >> WCP > WS >> CW. Wheat did not respond to N fertilizer when rainfall was below 450 mm during the growing season. Using these results strategies can be developed for establishing the N fertilizer rate applied to wheat as a function of rainfall, the preceding crop, and residual N in soil in order to optimize wheat yield and reduce nitrate pollution to groundwater.

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