Science et changements planétaires / Sécheresse


Optimizing rainfed sunflower crop management in the Meknès region (Morocco). II. Investigation using the Epic-Phase model Volume 11, issue 1, Mars 2000


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  • Page(s) : 19-27
  • Published in: 2000

This study was aimed at determining strategies to increase water availability for rainfed sunflower crops in the Meknès (Morocco) region using the validated Epic-Phase simulation model. Simulations concerned the effects of soil tillage, sowing date, cultivar earliness and crop density on sunflower production based on different initial soil water and soil depth hypotheses. A 2-year rotation (sunflower-wheat and wheat-sunflower) was simulated using climate data recorded in the Meknès region over a 37-year period (1960-1996). Sunflower yield was increased by cropping in deep soils with ploughing. Better results were obtained with late-maturing cultivars when densely sown in November or December. Late sowing in March led to quite low yields, with no differences between cultivar types (late-maturing, semi-early, early-maturing). Although the early sowing dates were synchronized with winter rainfall, there was still a problem of water deficit during grain filling due to high water depletion during the vegetative phase. This excessive water use is a constraint for efficient soil water management until crop maturity. Exposure to low temperatures in December and January is another drawback of early sowing. The optimal nitrogen application rate was found to be 80 kg/ha for winter sowing (split in two applications between sowing and the flower bud stage) and 60 kg/ha for spring sowing due to the lower yield potential. Current crop management strategies (including weed control and crop protection) will clearly have to be completely readapted prior to changing the sowing period (from spring to winter).