Structural Stability and Accumulation of Organic Matter in Some Soils under Cashew Tree Orchards in the Department of Touba in North-West Côte d’Ivoire

Abstract

Degradation of the physical quality of the soil is a common problem encountered in agrosystems, particularly in the case of open field cropping systems in the northern areas of Côte d'Ivoire. Thus, the structural stability of the soil, which is a good indicator of the sensitivity to threshing and to water erosion in relation to the accumulation of organic matter, was evaluated in two types of soil (Ferralsol and Cambisol) in cashew orchards, in two villages (Mahana and Sanankoro) producing cashew nuts, located the Department of Touba in the North West of Côte d'Ivoire. The objective of this study is to develop new technical routes that are better suited to further promote the sequestration of organic carbon in the soil. Soil samples were taken from open soil profiles at the two chosen sites to allow laboratory analyzes. The results indicate that the surface horizon of Cambisol (site 1) is more stable (Is = 0.78) than that of Ferralsol (site 2; Is = 1.08) with nevertheless relatively small thicknesses of horizons. The median horizons and those of depth, indicate a mediocre stability (Is vary from 1.03 to 1.62). In terms of the quantity of organic carbon, the estimated values vary from 1.96 to 4.53 t•ha −1 for Cambisol (site 1) and from 1.44 to 3.46 t•ha −1 for Ferralsol (site 2). These values remain relatively low especially at the level of the median horizons and those located in depths. Statistical tests have shown a very highly significant and negative association between the structural stability of soils and the amount of organic carbon in the different horizons. The relationship implies that organic carbon plays an important role in the structural stability of soil horizons under cashew tree orchards.