Strategies to improve field establishment of cover crops. A review

Cover cropping consists in sowing non-cash crops to improve regulating and supporting services without seeking provisioning services. Cover cropping has the potential for spatio-temporal diversification of cropping systems to help address food security while also improving environmental sustainability. However, cover crops are still poorly adopted by farmers worldwide. One of the key reasons behind this poor adoption is the difficulties in ensuring cover crop establishment that is further exacerbated by the current knowledge gaps. On the other hand, no study has yet summarized key published and unpublished information on cover crop emergence and field establishment that may help fill these knowledge gaps. In light of this, for the first time, we comprehensively review the literature to summarize and quantify information related to cover crop emergence and propose strategies for improving their field establishment. The major findings are as follows. (1) Detailed statistics on the share of arable land sown to cover crops are lacking, but the available information suggests that this share is increasing over the years ranging from 4% in the USA to 9% in the EU. (2) Four key factors—regulations and public policy incentives, economic factors, knowledge factors, and environmental factors—influence the adoption or non-adoption of cover crops by farmers. (3) Poor emergence and field establishment, due to unfavorable environmental conditions, is one of the most important obstacles to cover crop adoption across temperate regions worldwide. (4) Five forms of cover crop sowing are practiced by farmers that can be grouped into two major sowing strategies—sowing before and after harvesting cash crops—each of them presenting several strengths and limits. (5) A wide range of sowing equipment is available for farmers but their choice depends on several factors including work output and costs. Finally, we emphasize the role of a decision support system and modeling, for an optimal cover crop sowing and field establishment, which are key for enhanced quantity of biomass production and ecosystem service provisioning.