Tillage–crop residue management and rainfall–runoff relationships in the Alemaya catchment of Eastern Ethiopia

Abstract

A field study was conducted in the Alemaya catchment, Eastern Ethiopia, with the objective of determining the effect of tillage practices, crop reside cover and rainfall characteristics on runoff during two rainfall seasons on a clayey Regosol with 5% slope. Relationships between runoff and rainfall characteristics, such as the amount, intensity and erosivity were established from a two-year data set. The results on fields without crop showed that a minimum of 2 t ha-1 of fresh wheat residue is required to reduce runoff from low intensity storms and 4 t ha-1 of residue for high intensity storms with peak intensities of more than 55 mm h- 1. These norms can be used for estimating runoff under comparable soil and climatic conditions. A technique was also developed to estimate runoff from the rainfall intensity- duration curve and the mean soil infiltration rate.