Crop residue management and tillage systems for water conservation in a semiarid area of Morocco

In Morocco, agriculture is still empirical and most of the farmer's practices are inherited from colonization. Present Moroccan farming systems limit the opportunity to leave crop residue on the soil surface, which could help to conserve soil and water. Agricultural residues have many potential uses; food, feed; shelter, fuel, and soil amendments. The use of plant residues for purposes other than for soil surface protection may have serious consequences on the soil and crop productivity. Hence, this research was conducted to investigate (1) the potential of no-till residue cover and primary tillage practices to suppress water evaporation and replenish the soil and (2) the yield response of wheat (Triticum aestivum L.) and corn ( Zea mays L.) to residue management systems under contrasting water regimes. The study was conducted in a semiarid region of Morocco characterized by an average annual rainfall of 380 mm and a soil of clay loam texture.; The results of this study showed that wheat under no-till and minimum till residue management systems had more available moisture than more conventional tillage systems. For wheat, grain yield was proportionate to the quantity of wheat straw on the soil surface. For corn, intermediate wheat straw levels were more effective in manipulating soil water to favor plant growth and final grain yield than were higher residue levels or no cover. This type of relation was not found for corn. In general soil temperature did not significantly affect the growth of wheat and corn. The very poor performance of the no-till drills, especially for corn, used in this experiment greatly affected the experimental outcome. To avoid problems associated with seeding through a thick residue, special attention to seeding conditions and equipment is required. The results obtained in this study indicate that no-till could be used in semiarid Morocco without sacrificing yield. While only small differences in yields and Water Use Efficiency were found by the different soil management strategies, the difference between no-till and conventional tillage systems would likely increase with time under residue covered systems if appropriate machinery was available for mulched soils. (Abstract shortened by UMI.)...