Integrating Water, Nitrogen, and Salinity in Sustainable Irrigated Systems: Cover Crops versus Fallow

Abstract

Cover cropping techniques are efficient for reducing pollutant leaching, avoiding soil erosion, or enhancing soil properties of agricultural soils. However, few studies evaluate the overall effect of cover crop (CC) on agricultural ecosystem functioning, and it is necessary to ensure that advantages of CC are not compensated by potential negative effects such as soil salinization. To improve the understanding of these complex processes, the authors analyzed water, nitrogen, and salinity dynamics in a maize cropping system with CC (vetch, barley, and fallow treatment), which was introduced in the intercropping season using both an experimental and modeling approach. As compared with a control treatment, the CC reduced nitrate leaching (64% for the barley treatment and 29% for the vetch treatment) without increasing soil salinity. In addition, the CC reduced the top layer salinity when maize was sown. Although the CC reduced with respect to fallow the net salt losses, in these conditions, excessive irrigation to favor salt leaching was not needed and, therefore, deep-water contamination risk with nitrate was reduced.