Low unreliable rainfall and high evaporation potential in semiarid parts of Morocco, but also inappropriate management of soil resources, pl produce erratic crop yields and uncertain economic returns. The need to maximize soil water conservation and optimize wheat grain production in Moroccan dryland areas have contributed to the emergence of direct seeding technology in this region. A field experiment was conducted to investigate the effects of no-till, minimum till, traditional and deep tillage systems on wheat yield as well as on water use efficiency. The experiment was conducted from 1995 to 1999, under rainfall regimes that varied from as low as 195 mm to 440 mm. Grain yields under no-tillage (2.47 Mg ha(-1)) were equal to those obtained using a chisel plow or deep tillage and superior to yields obtained by rotovating, conventional off-set disking, stubble mulching ol subsurface traditional tillage. Water use efficiency (6.6-7.1 kg mm(-1) ha(-1)) was similar following no-till, deep disking and chisel plowing while other tillage systems had lower but similar values (varying from 5.4 to 5.9 kg mm(-1) ha(-1)). Tillage systems did not differ significantly in terms of total dry matter or straw production and water use. Improvements in notill drill design, which focus on proper seed and fertilizer placement and which prevent seed and straw being placed in close contact, an needed and may contribute to enhanced wheat yield and biomass under no-tillage.
