Maize-legume intercropping system improved soil quality under irrigated and rainfed conditions

Abstract

Maize monoculture, which predominates smallholder cropping systems in NE South Africa negatively affects soil quality. We assessed the effect of rainfed and irrigated maize-legumes intercropping systems (sole maize, sole chickpea, sole mungbean, maize+chickpea, maize+mungbean) on soil quality variables at Mankweng and Thohoyandou, South Africa in summer 2019/2020. Three soil samples were randomly collected from each plot at 0–20 cm depth after harvesting at both sites for the determination of bulk density (BD), aggregate stability (AS), pH, electrical conductivity (EC), soil organic matter (SOM), soil organic carbon (SOC), phosphorus (P), ammonium (NH4+), nitrate (NO3-), soil active carbon (SAC), and potentially mineralizable nitrogen (PMN). Intercropping affected pH, SOM, PMN, SOC, P, NH4+ and NO3-. Maize + chickpea (Thohoyandou and Mankweng) and maize + mungbean (Thohoyandou) exhibited higher NH4+ content than sole maize. NO3- was higher under intercropping compared to sole maize at both sites. Mungbean appeared to have greater effect on soil quality parameters than chickpea and intercropping was generally more beneficial under irrigated systems. Clearly, incorporation of legumes as intercrops in maize-based cropping systems may enhance soil productivity.