The cover crop termination choice to designing sustainable cropping systems

The use of winter cover crops (CCs) in annual rotations is a tool to increase agroecosystem sustainability. To optimize their benefits, the choice of how to terminate CCs in spring is crucial, because this decision may lead to differences in soil–plant variables and affect cash crop productivity. The use of a roller-crimper is an emerging option in both conservation and organic agriculture but its adoption in Mediterranean regions is still rare. In this work the objective was to identify best CC termination practices to maximize benefits and increase agro-ecosystem resilience. To this end a field experiment with a barley/vetch (Hordeum vulgare L. / Vicia villosa L.) CC mixture followed by an irrigated corn (Zea mays L.) was conducted in Central Spain in three consecutive years. Each year, three CC termination methods (roller-crimper, glyphosate + roller-crimper, and CC residue incorporation) and four post-emergence operations to reduce weed pressure in summer (post-emergence herbicide, inter-row cultivator, the combination of the two, or without operation) were compared. The effect on the spring soil water content and temperature, weed control, soil inorganic N and the corn grain yield and N content were evaluated. Energy and economic analyses were conducted. An ineffective CC termination by roller-crimper was overcome when using glyphosate or post-emergence herbicides. However, the roller-crimper was less dependent on post-emergence operations than residue incorporation to achieve proper weed control and attain good productivity. The results showed that in early corn growth stages, roller-crimper use enhanced the soil's water conservation and decreased soil temperature compared to CC residue incorporation. Moreover, the energy cost was lower for roller-crimper termination. Our findings suggest that the roller-crimper increases the environmental sustainability in Mediterranean regions, but farmers may encounter economic risks. Further research is needed to find proper conditions that maximize the potential of this CC termination method under Mediterranean conditions.