Modelling crop production potentials for yield gap analysis under semiarid conditions in Guquka, South Africa.
Verdoodt, A. Van Ranst, E. Van Averbeke, W.
Verdoodt, A.
Van Ranst, E.
Van Averbeke, W.
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Abstract
Hierarchical crop growth models can contribute significantly to land quality research because the yield gap between the estimated optimum and the actual crop production has been identified as a major land quality indicator. This study describes a three-level, hierarchical crop production model, simulating radiation-thermal, water-limited and natural production potentials of annual crops. Input requirements have been kept low to ensure its applicability to developing regions, which often have access only to limited data. The simplicity of this model also has disadvantages: inconsistencies have been reported when applying this model in semiarid regions, which are characterized by very irregular rainfall patterns. Revision of the water balance, which simulates the availability of water, was required. The modified model was validated using the experimental yields of maize and sun¯ower in Guquka, a semiarid region of South Africa. Yields were estimated very well, possible improvements to crop production were identified and implications for land-use planning highlighted. Yield gap analysis revealed that radiation, sunshine and temperature are favourable for crop production, but the heavy dependence on rainfall makes the region very vulnerable to drought, with devastating impact on yields. The generally low chemical soil fertility further reduces crop performance.
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Date
2003-12-04
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Publisher
Wiley
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Keywords
Yield gap analysis, Land-use planning, maize, Sun¯ower, Semiarid region, South Africa