Leveraging functional traits of cover crops to coordinate crop productivity and soil health

1. Plants act as ecosystem engineers playing fundamental roles in steering their surroundings, including soil abiotic and biotic conditions, soil organisms, and the complex soil food web they comprise. Trait-based approaches have been considered a ‘Holy Grail’ in linking plants to ecosystem functions, but the mechanistic relationship between plant traits and the soil food web as an indicator of soil health remains poorly understood. 2. We examined this relationship for 16 cover crop species differing in leaf and root traits in a field experiment where corn (Zea mays) was the main crop. Based on functional traits, the cover crop species were categorized into two ecological strategies at either end of the resource acquisitive-conservative spectrum. We investigated the effects of cover crop ecological strategies on corn productivity and soil health. We used soil nematodes as an indicator of soil health and analyzed soil physico-chemical properties and microbial community activities. 3. We found that acquisitive cover crops supported higher soil resource availability, bacterial energy channels in the soil food web, and greater corn productivity than conservative cover crops. In contrast, conservative cover crops supported higher abundances of fungivores and omni-carnivores than acquisitive cover crop, which reflected a more structured and complex soil food web, implying a healthier soil ecosystem. Conservative cover crops also increased corn productivity compared to the no cover crop control treatment. 4. Synthesis and applications. Collectively, this work shows that cover crops with distinct ecological strategies had their own strengths to enhance ecosystem functions: acquisitive and conservative cover crops improved crop productivity and soil health, respectively. These results indicates that farmers and policy makers can make trait-based choices in selecting cover crop best serving the local needs. This points to a win-win solution for food production and ecosystem sustainability.