Optimizing Agronomic Practices for Clover Persistence and Corn Yield in a White Clover–Corn Living Mulch System

Abstract

Core Ideas Living mulch cover crops help stabilize erosive soils during corn production. Wide rows enable the living mulch cover crop to re‐establish for subsequent cropping. Herbicide bands must be kept to a minimum width to permit living mulch. Removal of crop residue is essential for white clover to perenniate in the living mulch system. White clover can supply over 100 kg ha−1 N to corn in the living mulch system. The area dedicated to corn (Zea mays L.) production increased 50% in the southeastern United States between 2006 and 2016, but producers need to find production systems that mitigate environmental impacts on erosive soils. Utilizing a perennial legume in a living mulch system may help stabilize the soil. The objectives of this study were to identify the most successful herbicide banding pattern (20 or 40 cm), corn row spacing (75 or 90 cm), and corn population density (60,000 or 90,000 plants ha−1) to optimize potentially mineralizable nitrogen (PMN) from white clover (Trifolium repens L.) and maximize clover regrowth in a living mulch system. Plots were established at Floyd and Oconee Counties, Georgia, and tested over 2014 and 2015. Clover persistence and regrowth was best when initial clover suppression used a 20‐cm band and corn was planted on 90‐cm rows. Herbicide‐induced PMN was greater for the wide herbicide band width, but shade‐induced PMN was greater from the narrow band width. Corn shaded the clover at approximately 40 d after planting (DAP) and clover responded by senescing biomass as shading increased. Shading resulted in the majority of PMN regardless of other treatments variables. Corn grain yields were greater in the high population treatments, but there was a year × location × herbicide band width interaction. Considering clover persistence, PMN, and corn grain yield, we conclude that corn planted on 90‐cm rows in 20‐cm wide herbicide bands of dead clover is the best treatment for the living mulch system.