Impact of wheat-vetch temporary intercropping on soil functions and grain yield in a dryland semi-arid environment

Background and aims While a limited number of studies have investigated cereal-legume temporary intercropping in organic systems, the potential for temporary intercropping to improve soil properties or cash crop yield/quality in conventional systems remains unknown. Methods A field experiment comparing monoculture wheat to wheat with a temporary (9 week) vetch intercrop was conducted in a water-limited environment. Wheat root growth and biomass, plant available water (PAW) and soil mineral nitrogen (N) were measured at anthesis (9 weeks after vetch termination) and grain yield/protein were determined at maturity. Soil parameters including soil total carbon (C) and N, hot water extractable C (HWC), water soluble C (WSC), citrate-extractable protein, microbial biomass carbon (MBC), and soil enzyme activities were also assessed. Results Compared to monoculture wheat, temporary vetch-wheat intercropping increased MBC, HWC and WSC by 37%, 15% and 7%, respectively, across the monitoring period. Temporary intercropping increased the activity of C- and N-acquiring enzymes by 45% compared to monoculture wheat. At anthesis, the intercrop treatment had 30 mm more PAW and an additional 20 kg mineral N ha −1 to 90 cm depth than the monoculture wheat. This didn’t result in higher grain yields, presumably because spring rainfall was adequate for grain filling, and didn’t increase grain protein, likely because the system wasn’t N-limited. Conclusion Higher mineral N and PAW under wheat-vetch intercrops at anthesis suggests temporary intercropping could increase wheat grain protein under the right conditions, and potentially increase grain yields in seasons with limited rainfall during grain filling.