Reduced-Tillage Organic Corn Production in a Hairy Vetch Cover Crop

There is interest in developing no-tillage systems for organic farming; however, potential limitations include the inability to control weeds and to provide sufficient crop available N. A 3-yr field experiment was conducted on organically certified land to explore roller-crimper technology for terminating a hairy vetch (Vicia villosa Roth) cover crop in a reduced-tillage compared to a disk-tillage organic corn (Zea mays L.) production system in Maryland. Within this tillage comparison, factors including the corn planting date and post-plant cultivation were examined for optimizing reduced-tillage organic corn production. Corn yield in roll-killed hairy vetch treatments where corn was planted by mid-June and that received high-residue cultivation was similar or higher than the best treatments with disk-killed hairy vetch. Delayed corn planting dates had little impact on corn yield in either disk- or roll-killed treatments, a result consistent with the similarity in weed biomass after cultivation, fertility, moisture, and radiation across planting dates. In 2 yr with supplemented weed populations, weed biomass was the major driver determining corn yield, which was reduced by 53 to 68% relative to weed-free control plots in the absence of post-plant cultivation, and by 21 to 28% with post-plant cultivation. In a year with low, natural weed populations, weeds had no significant influence on yield. These results demonstrate that organic corn production in a reduced-tillage roll-killed cover crop system can provide similar yields to those in a traditional tillage-based system, but also highlight the importance of maintaining low weed populations to optimize corn yield.