Effect of land use changes on some important soil properties in cotton-based farming system in Burkina Faso

ABSTRACT

Continuous and intensive cropping without restoration of soil fertility has depleted the nutrient base of most soils in the semi arid zone. A field survey was carried out in 2000 in Bala village in the cotton production zone of western Burkina Faso to assess the effect of land use changes on soil chemical and physical changes. The methodology consisted of land use analysis at contrasted periods; field sampling and measurements; and farmers' interview. Land use analysis was done at three periods 1952; 1981 and 1999. Soil samples were taken in farmers' fields selected on the basis of their equipment level and the cultivation duration. Two fallows were selected and considered as control situation. Aerial photos analysis showed that the proportion of the land under cultivation was increased at about 38.3 from 1952 to 1999. Soil chemical analysis showed that soil total P and K were significantly higher in soils manually cultivated than in soils cultivated with animals and tractors. Soil pH was lower in motorized farmers' fields than in the other categories. Soil organic matter and N content were not affected by all the studied factors. The percentage of sand in the soil increased with the performance of the equipment. The opposite situation was observed with soil silt content. Soil stability was not significantly affected by any of the factors. But the numerical values showed a more stable soil structure under fallows than when soils were cultivated. From the results; it appeared that the fundamental cause of land degradation in the area is the farming system than the nature of the crop being grown