Furrow irrigation erosion and management

Irrigation-induced furrow erosion reduces topsoil depth and pollutes surface waters. A variety of interacting factors, including inflow rate, slope and soil type, are known to affect furrow erosion. Data are inadequate to understand the furrow erosion process sufficiently well to recommend irrigation practices that maintain high levels of water quality and conserve soil. We performed furrow erosion field studies on two soils (a loamy textured alluvial soil and a clay loam cracking soil) with slopes ranging from 0.3 to 0.8%. Three inflow rates per furrow were applied in each of three irrigations. We found net rates of soil loss in the upper part of the furrow that were up to six times higher than the average net rate for the whole furrow. The soil loss was related to the inflow rate by power functions. High inflow rates on furrows with slopes greater than 0.3% caused unsustainable soil losses. However, at least in the loamy textured soil, it is possible to maintain high irrigation uniformity and application efficiency (within the range 80-85%), while keeping soil losses within a sustainable limit. An analysis of the sediment load data made in the frame of a simple conceptual model helped to explain the dynamics of the furrow erosion process and to establish the basis for modeling furrow erosion.