干旱区生态环境知识资源中心

Land degradation caused by water erosion affects large areas of the world. In the arid regions, erosion is accentuated by fragile environmental conditions and limited economic and/or technical mitigation alternatives. Cropping systems are seen as promising tools. A 2-year experiment was conducted at Jordan University Station for Arid Land Research at Muwaqqar to investigate the influence of plant densities (250, 300, and 350 plants m(-2)) under different cropping systems (sole cropping, traditional sole cropping-up- and-down the slope-and contour strip intercropping) of barley (Hordeum vulgare L.) and common vetch (Vicia sativa L.) yields, soil and water losses. Average intercropping yields of vetch and barley were significantly increased (by more than 50%), especially at plant density of 350 plants m-2 as compared to their sole crops planted under similar plant density. This increase in yield was generally associated with a reduction in water and soil losses. Traditional sole cropping gave the highest significant runoff coefficients (above 0.30), and the lowest significant yields. Runoff coefficients were reduced to 0.17 as a result of planting barley and vetch under contour strip intercropping at a plant density of 350 plants m(-2). The average land equivalent ratios (LER) for most intercropping treatments were greater than one, which indicates the superiority of intercropping over the sole cropping system. The normalized difference vegetation index (NDVI) was highly correlated with yields, water, and to some extent, soil losses. This indicated the possibility of using remote sensing to build an inventory of spatial and temporal variation of vegetation cover to serve land degradation mitigation efforts.