Measurements of Runoff and Soil Erosion at an Erosion Plot Scale with Particular Reference to Tanzania

Abstract

The principal results of a series of experiments designed to measure runoff and soil losses at an erosion plot scale in tropical and sub-tropical African environments are tabulated and discussed. Most of these results are not widely known, even in Tanzania. Methodology as well as data are commented upon. Erosion plot data are particularly significant as a guide to local land use practice at the farm plot or field scale and as indicators of the magnitude and processes involved in runoff and soil erosion. The problems of extrapolating the results to larger scales and different areas are discussed. In zones such as semi-arid central Tanzania where soil moisture availability is the chief limitng factor on crop yields and where soils are readily eroded under careless cultivation or through overgrazing, quantitative data on runoff and soil erosion are of particular value. In zones like the mountain footslopes of Kilimanjaro and Meru, where rainfall is higher, moisture deficiency is still a problem at the end of the dry season and soil erosion can be serious when steep land is cleared for cultivation.