Properties and Sensibility to Physical Degradation of Soils under Cotton Cropping in Korola Watershed, Sikasso Region, Mali

Abstract

Soil physical, chemical and biological degradation is a global problem, which must be monitored by each country in order to have better decision-making for agriculture and environment. In this case, study has been undertaken in Mali at agricultural watershed scale. The present paper is related to Korola watershed (1245.3 km2). Here, and in the major part of Sikasso region, cotton cultivation for industry was introduced during the 1960s. Soil degradation is considered as a handicap to the improvement of cotton production, a general problem in Western and Central Africa.  A deeper understanding of soils and their sensibility to degradation is needed in order to choose better strategies to improve their management and productivity. The methodology used in the present study includes soil profile descriptions, particle size analyzes, carbon, nitrogen and pH measurement, the use of pedotransfer functions to assess soil structure and their sensitivity to erosion. In Korola watershed, 3 soil types (soil1, soil2, soil3) are selected by farmers for cotton cropping. Soil1 (Guinin dugukolo) and soil2 (Mura dugukolo) have a high amount in silt, while soil3 (Ciencien dugukolo) is rich in sand. All these soils are poor in organic matter (≤ 1%) and present a high risk of acidification. The index of battance (IB) of surface horizons (respectively 15.9, 11.0 and 15.4 for the three types soils) indicate a unfavorable structure. The destructuration index (St) indicate a high sensibility to soil erosion. The values of soil erodibility index (K) are respectively 0.44; 0.55 and 0.09 for the three types of soils.