Improving the sustainability of farming systems under semi-arid conditions by enhancing crop management

Abstract

Under semi-arid conditions, water is the most limiting factor for ensuring the sustainability of Mediterranean agriculture. Proper management of practices such as irrigation, fertilization, and changes in sowing date and sowing density can contribute decisively to efficient water management in these agricultural systems. Thus, the aim of this study was to assess the effect in terms of yield and profit of combining those agricultural practices, and subsequently to define strategies for the sustainable intensification of semi-arid agricultural systems in southern Spain. The study focused on sunflower as a representative crop.Sustainable intensification practices were evaluated through a series of experiments, revealing the prominent role played by water availability in their performance. Thus, high sowing density provided much more satisfactory yield results compared to the traditional sowing density, and it was observed that this yield increase was related to water availability: higher yield increases (around 27%) were obtained with deficit irrigation strategies than under severe deficit irrigation or rainfed conditions (around 16%). Other intensification strategies such as support irrigation and early sowing date also generated satisfactory yield increases (around 45% and 30%, respectively). Finally, interactions between irrigation and fertilization indicated that under limited water availability, very low N-fertilization rates were required. All these results led to the conclusion that the combination of high sowing densities, early sowing date, deficit irrigation and limited fertilization constitutes an innovative intensification strategy for sunflower under semi-arid conditions.An economic analysis of the proposed agricultural practices also revealed a clear connection between water availability and optimized management of sowing density, sowing date and fertilization. These results confirmed that technical advisory services provided to farmers should focus on integrated site-specific crop management, especially under semi-arid conditions with severely limited water availability.