Effects of conservation agriculture on runoff, soil loss and crop yield under rainfed conditions in Tigray, Northern Ethiopia

The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for three years (2005-2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5×19 meter plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 meter intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (P