Modelling soil changes under agroforestry

Abstract

In the older approach to soil conservation, the emphasis was on controlling the rate of soil loss, expressed as tonnes per hectare or millimeters of soil depth. Conservation measures were directed at reducing erosion to a presumed acceptable rate, called soil-loss tolerance. Earlier attempts to assess economic terms were made on the basis of reduction in soil erosion control should come first, as a prerequisite to other agricultural improvements. Recent research has changed this emphasis in several ways. It has been recognized that the effects of erosion are by no means limited to reduction in soil depth. Equally important are loss of nutrients, organic matter, and through the latter, deterioration in soil physical properties. This is leading towards integration between tow aspects of soil conservation: erosion control and maintenance of fertility. Both are necessary to achieve land use which is sustainable as well as productive.