Soil degradation under irrigation

Abstract

Irrigation is a precondition for stable crop production in areas characterized by marked variability in rainfall distribution. Despite substantial investment in irrigation projects in the past decades, global irrigated cropland area has hardly grown. Here we discuss the factors related to the sustainability of irrigation and strategies to alleviate them. Water resources deterioration, diversion of water for other uses, and soil degradation are the major factors affecting the environmental sustainability of irrigated agriculture. Water logging results from the tendency to apply water in excess of irrigation requirements. It leads to reduced aeration, nutrient uptake, and crop yields. Salt buildup occurs through the process of capillary rise when the water table rises close to the surface. Salinity risks also increases when saline water is used for irrigation and when poor fertilizer and poor irrigation management are combined. Groundwater drainage is the ultimate precautionary measure against groundwater rise and salt accumulation, but its timely installation is essential for optimal result. Constant soil monitoring and the use of systematic diagnosis testing could also reveal the incipience of soil salinity. Future global warming would likely exacerbate water demand for irrigation with the implications that crops would grow in hotter, drier, and more saline conditions. The ability of irrigated agriculture to meet future challenges would therefore depend on the progress of new research to enhance adaptation to these changes. © 2008 Springer Netherlands.