Crop Residue Management and Tillage Systems for Optimizing Crop Production and Improving Soil Quality In Moroccan Drylands.

Some 40% of the earth’s land surface is covered by semi-arid and arid ecosystems, otherwise known as drylands.  Virtually all of Morocco is classified as drylands. These lands are characterized by an unfavorable climate, marked by spatio-temporal irregularities, coupled with growing tensions on soil and water resources, which stresses the importance of a progressive orientation towards an economically feasible and environmentally viable agriculture. Rational use of no-tillage technologies, conservation cropping systems, and crop residue management can have noticeable impacts on crops and soils. Agronomic benefits from no-tillage systems compared to traditional and conventional tillage systems are well shown from research sites, either at the experimental or farmer level. The efficiency of a no-till system for carbon sequestration is enhanced when used in combination with high intensity wheat rotation and reduction of summer fallow. In other terms, while soil organic matter (SOM) levels in Morocco are low. i.e., < 1–2%, conservation cropping systems managed under no-tillage technologies, notably with forage legumes in rotation with cereals, caused sustainable increases in crop yields associated with higher SOM. No-tillage system ameliorated organic matter labile fraction and soil pool in nitrogen, phosphorus and potassium. Water conservation and soil quality improvements were found proportional to residue cover level under no-tillage, while wheat yield could reach an optimum at 2-4 Mg ha-1 of surface residues. As an important option for implementing no-tillage in farmer’s system, combining partial straw exportation and forage based triennial rotation was found to satisfy both water storage for stabilizing wheat yield and enhancement of soil organic matter. Reductions in soil erosion and carbon emissions under no-tillage systems were obvious from recent research studies. Supplementary studies should be undertaken in order to generalize the effect of no-tillage systems on the improvement of crop yields and on the restoration of soil quality. Other biochemical and chemical studies of soil organic matter are needed to comprehend better the carbon dynamics and microbial activity. Through modeling approach, agronomic and environmental benefits from no-tillage systems could be ameliorated and better recognized in prevision of future scenarios of climate change (rise of temperature and evapotranspiration) that may occur in Morocco. Technically no-tillage systems can be widely adapted to farmer’s conditions. However, attempts to transfer these systems have not yet find satisfying environment for agricultural revolution.  In other words, despite this progress in research, still farmers feel that conventional tillage systems are necessary to produce a crop and that plant residues are important for livestock diet. Research-development activities should be encouraged for wide dissemination of benefits from no-tillage systems and establishment of conservation agriculture in Morocco.