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

Abstract

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.