Cover Crops Impacts on Nitrogen Scavenging, Nitrous Oxide Emissions, Nitrogen Fertilizer Replacement, Erosion, and Soil Health

By reducing nutrient leaching and erosional losses, increasing soil organic matter, fixing N2, and providing a living mulch and forage for livestock, cover crops can improve long-term economic environmental sustainability. However, obtaining these benefits depends on the selection of the most appropriate plant species and management practices. For example, annual ryegrass (Lolium multiforum Lam.) can develop dense, shallow root systems within a short period, creating a vegetative mat that provides a cushioning effect against rain drop impact and helps prevent erosion. Other species, such as barley (Hordeum vulgare L.), may have very deep roots, which are efficient in scavenging nutrients. Leguminous crops, like hairy vetch (Vicia villosa Roth), and clover (Trifolium spp.), have the ability to fix atmospheric N and release it to subsequent crops. The objectives of this chapter are to: (i) provide an overview of how cover crops may fit into a soil fertility program, (ii) discuss the use of cover crops as N scavengers and the impact on N2O emissions, (iii) provide examples of how to determine fertilizer replacement value, (iv) discuss the impact of cover crops on P and soil loss through erosion, and (v) examine cover crop impact on soil health.