Irrigated barley-grass pea crop mixtures can revive soil microbial activities and alleviate salinity: Evidence from desertic conditions of southern Morocco

Abstract

Abstract Soil salinity and aridity seriously limit productivity of annual forage crops. This problem can be remedied by cropping systems that activate microbes to modify soil structure and bind to excess salts. In randomized complete block experiments, we tested whether these mechanisms might be replicated in low, moderately and highly saline soils of Laayoune-Morocco (salt-affected soils) under irrigated grass pea and barley monocrops and their mixtures in 50–50% and 70 − 30% pure live seeding rates. The 50–50% barley, grass pea mixture significantly enhanced (p < 0.0001) CO2-C flux in low salinity and revived microbial activities in extremely saline conditions compared to monocrops. Irrigation acted independent of treatment to reduce soil salinity and sodium concentrations across salinity regimes. There were negative curvilinear relationships between water filled pore space and CO2-C flux along a continuum of increasing soil salinity. There were positive curvilinear relationships between shoot dry matter yield and CO2-C flux of grass pea monocrop and the 50–50% bipartite mixture of grass pea and barley along a range of reducing soil salinity. Overall, barley-grass pea mixtures can enhance microbial activities in moderate salinity and rejuvenate extremely saline soils with optimized irrigation at ~ 35% water filled pore space.