Effet du semis direct sur les propriétés physico-chimiques des sols au Maroc

Abstract

In Morocco, the irregularity of the climate, particularly in semi-arid and arid zones, accompanied by the intensive plowing of soil, can strongly contribute to the depletion of organic matter, causing soil instability; and therefore, threatening sustainability. However, the improvement of the soil quality and its protection against the erosion forms depend on the soil tillage methods used. For these reasons, conservation agricultural practices, particularly no-tillage, has been proposed as a reliable alternative technique; it has qualified as sustainable in several studies. This thesis aims to evaluate and improve the knowledge of the important effects of the no tillage system on the physical and chemical properties of Moroccan soils. Three experimental sites were chosen at different durations: site I (on the short- and medium-term), site II (on the medium-term) and site III (on the long-term). Compared to conventional tillage, the no tillage system gave the best results for most of the studied properties. Indeed, the organic matter and humic acid contents were observed to be significantly high (P -value <0.05) at soil surface for sites I and II and up to 40 cm depth for site III. This reinforces the cohesion between the soil aggregates causing better structural stability under this new system. Water content was observed in favor of the no tillage system from the short-term experiment. The results of total nitrogen and assimilable phosphorus were observed significantly higher in favor of the no tillage system after long-term testing in the soil surface. Furthermore, for bulk density and rate of infiltration), the difference between the two treatments, decreases with time. Finally, the no tillage system is a reliable solution to improve the physical and chemical properties of the soil and this will allow for better soil conservation.