Soil tillage and water infiltration in semi-arid Morocco: the role fo surface and sub-surface soil conditions

Production of cereals in a dryland farming system forms an important part of agricultural production in Morocco. Yield levels on the Saïs Plateau between Meknès and Fez in the semi-arid zone, however, remain low possibly because of sub-optimum water use due to inefficient tillage systems. A study was carried out to investigate the effect of soil tillage operations on water infiltration. Two systems of seedbed preparation on a silty clay soil were compared: traditional disc harrow (‘cover crop’) versus reduced tillage using a spring tined cultivator (‘vibrocultor’). Infiltration processes were studied using a rainfall simulator applying rainfall typical for aggressive events in the region. The effect of tillage and rainfall on the structure of the soil was assessed by both quantitative and descriptive methods. It was found that the disc harrow caused excessive pulverisation and seal formation under rainfall. Water infiltration, on the other hand, was not hindered by plough sole formation or subsoil compaction. It is suggested that reduced tillage by the spring tine cultivator is less costly and results in lower losses of water by runoff, thus leaving more water available for the crop.