Effects of barley‐pea intercropping on soil carbon, crop productivity, and grain quality in a low‐input temperate agroecosystem

Intercropping has the potential to help adapt arable agriculture to climate change, but its effects on soil carbon and crop production in temperate agroecosystems remain uncertain. This study examined the effects of temperate intercropping systems on soil carbon and crop productivity. The study focused on two barley ( Hordeum vulgare L.) cultivars with contrasting phenotypic traits (high‐yielding vs. water stress‐tolerant) intercropped with pea ( Pisum sativum L.) and their three corresponding monoculture systems, grown without agrochemical inputs. During a 2‐year field experiment in Scotland, soil properties were investigated on six occasions at two depths, upper (<5 cm) and lower (25–30 cm) topsoil. Crop yields and grain quality (i.e., grain carbon and nitrogen concentrations) were also assessed. Despite peas failing before harvest, intercropped barley exhibited yield gains of 90–132 g m −2 based on net effect metric and up to 10% in partial land equivalent ratio compared to barley monocultures. By the second year, total carbon concentration increased by 8.1% in the upper topsoil in intercrop of high‐yielding barley cultivar compared to its monoculture (23.6 g kg −1 ). Also, grain carbon and nitrogen concentrations were higher for intercropped barley than monocultures, with the stress‐tolerant cultivar increasing grain carbon concentration by 5.7% over its monoculture. These findings demonstrate for the first time in temperate agroecosystems that low‐input barley‐pea intercropping could at least maintain or increase soil carbon and grain quality without compromising yields but dependent on barley cultivar traits. Intercropping can therefore potentially help adaptation to and mitigation of climate change in agroecosystems.