Intercropping with service crops provides multiple services in temperate arable systems: a review

Abstract

Service crops are crops grown to provide services to other cash crops, rather than for production purposes, with the ultimate aim of improving the environmental and production performances of cropping systems. Service crops can be intercropped with cash crops to facilitate interactions between crops and to optimize the use of the cropping season. Many terms exist to describe these practices, which highlights their diversity. However, this diversity of terms may be a source of confusion. Here, we present an overview of the current uses of intercropped service plants in temperate cropping systems, with the main services they provide and their management. (1) First, we show that a limited range of service crop species, mostly from the Fabaceae family, have been studied to date. This finding suggests that the diversity of species and cultivar resources that can be used as service crops has been poorly explored in the literature. In contrast, the combinations of service and cash crops tested appear wider. We address this diversity by defining synchronous intercropping, living mulch and relay intercropping. (2) Then, we show that intercropped service crops can efficiently reduce weed biomass and pest attacks and improve nitrogen cycling, thereby increasing soil fertility and improving crop nutrition. The intensity of these services is positively associated with service crop biomass, but excessive service crop biomass increases the risk of competition with cash crops. (3) The balance between the services and disservices provided can primarily be interpreted in terms of biomass production of coexisting crops. The resulting effect of service crops on cash crop yield is variable and reflects the integration of the effects of the various individual services, together with possible disservices. (4) The diversity in management methods makes it possible to manage this trade-off and to adapt the system to different conditions with a few tested species.