Evapotranspiration, single and dual‐crop coefficients, and water, radiation and nutrient use efficiency indicators in irrigated protein‐rich plant species in semi‐arid conditions

Background The present study aimed to determine the water requirements and natural resource use efficiency of protein‐rich species under semi‐arid conditions. A field experiment was conducted from October 2020 to February 2023 with five species (alfafa, gliricidia, leucaena, moringa, and pigeon pea) in a randomised block design, with four replications. Data were obtained from productivity (Y DM ), crop evapotranspiration (ETc) and its partitioning, single‐ (Kc) and dual‐crop coefficients (Kcb and Ke), crop water use efficiency (WUE), crop water productivity (WPC ETc ), system water productivity (WPc R+ID ), irrigation water productivity (WP ID ), and nutrient (NUE) and radiation use efficiency (RUE). Results Gliricidia showed the lowest average daily ETc (~4.0 mm day −1 ) and higher transpiration contribution (67%), resulting in greater average Kcb values (~0.63) compared to other species. In contrast, moringa presented higher mean Kc values (~0.93), while the other crops had similar values (~0.85). In terms of productivity and efficiency, gliricidia outperformed the other crops (Y DM = 1.298 kg m −2 ; WPC ETc , WPc R+ID , and WP ID equal to 3.467, 2.906, and 8.102 kg m −3 , respectively; NUE equal to 568.384, 61.746, 831.400, 403.626, and138.564 g ha −1 mm −1 , respectively for N, P, K, Ca, and Mg; and RUE = 1.418 g MJ −1 ). In turn, alfalfa showed a higher annual production frequency (11.4 cycles year −1 ). Therefore, the present study made it possible to expand water and production management, supporting better species selection. Conclusion In general, gliricidia is recommended in semi‐arid production systems for higher productivity, efficient resource use, and lower water demand, while in agroecosystems that require a continuous supply of forage, alfalfa is recommended.