Intercropping dry bean (Phaseolus vulgaris L.) with Cucumis myriocarpus and Cleome gynandra under deficit irrigation: impacts on soil physicochemical properties, water-use efficiency and crop growth

Abstract

Water scarcity is a major constraint limiting agricultural productivity in semi-arid regions. Developing sustainable production systems that improve water-use efficiency while maintaining soil physicochemical quality is therefore essential. This study evaluated the combined effects of cropping systems and deficit irrigation on instantaneous water-use efficiency (iWUE), soil physicochemical properties, nutrient dynamics, crop growth, and productivity in dry bean ( Phaseolus vulgaris L.)-based intercropping systems with Cucumis myriocarpus and Cleome gynandra . A field experiment was conducted over two growing seasons (2023/24 and 2024/25) using three cropping systems and three irrigation regimes supplying 100% (full irrigation, FI), 75% (moderate deficit irrigation, DI), and 50% (severe DI) of crop water requirements. Measurements included iWUE, soil physicochemical properties, exchangeable cations, crop growth, biomass production, and yield. Irrigation level had a greater influence on iWUE than cropping system. Severe deficit irrigation (50% DI) significantly reduced crop growth, biomass accumulation, and yield, whereas full irrigation (100% FI) generally produced the highest performance. Moderate deficit irrigation (75% DI) maintained satisfactory productivity while reducing water input, demonstrating its potential as a water-saving strategy. Both cropping system and irrigation regime significantly affected soil physicochemical properties and exchangeable cations (Ca, Mg, and K). Intercropping improved soil conditions by reducing bulk density and enhancing soil pH and nutrient cycling compared with sole cropping. However, dry bean-based systems maintained higher exchangeable cation concentrations and cation exchange capacity than C. gynandra -based systems. Soil nutrient availability declined progressively with increasing water deficit. Sole dry bean under full irrigation recorded the highest growth and yield. Although intercropping reduced dry bean yield compared with sole cropping, the dry bean + C. myriocarpus intercrop consistently outperformed the dry bean + C. gynandra intercrop under water-limited conditions. The findings demonstrate that irrigation management plays a more decisive role than cropping system in determining water-use efficiency and crop productivity under semi-arid conditions. Moderate deficit irrigation (75% DI), when combined with compatible intercropping systems, particularly dry bean + C. myriocarpus , offers a practical strategy for conserving irrigation water while sustaining crop productivity and improving soil physicochemical quality. These results support the adoption of integrated water and cropping management practices to enhance the resilience and sustainability of crop production in water-limited environments.