Reduced-tillage organic corn production in a hairy vetch cover crop

Authors: Teasdale, John; Mirsky, Steven; Spargo, John; Cavigelli, Michel; Maul, Jude

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2012
Publication Date: 2/29/2012
Citation: Teasdale, J.R., Mirsky, S.B., Spargo, J.T., Cavigelli, M.A., Maul, J.E. 2012. Reduced-tillage organic corn production in a hairy vetch cover crop. Agronomy Journal. 104:621-628.

Interpretive Summary: There has been increasing interest in organic farming among growers and in organic food products among consumers in recent years. There is also much interest in developing reduced-tillage organic systems that would combine the soil protecting capacity of conventional no-tillage systems with the inherent soil building capacity of organic systems. However, inability to control weeds and to provide sufficient plant available nitrogen are potential limitations of using conservation tillage practices in organic farming. This research was conducted to explore the use of roller-crimper technology for terminating a hairy vetch cover crop in a reduced-tillage system compared to a standard disk-tilled system for organic corn production in Maryland. Results of a three year field experiment on certified organic land showed that corn yield in roll-killed hairy vetch treatments that were planted to corn before mid-June and that received high-residue cultivation was similar or higher than the best treatments with disk-killed hairy vetch. Corn yield losses of 21-28% were still sustained when weed populations were high, underlining the importance of maintaining low weed populations for optimizing organic corn yields. These results will support growers and agricultural professionals interested in adopting reduced-tillage organic production systems.

Technical Abstract: There is much 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 three-year field experiment was conducted on organically-certified land to explore the use of roller-crimper technology for terminating a hairy vetch (Vicia villosa Roth) cover crop in a reduced-tillage system compared to a standard disk-tilled system for organic corn (Zea mays L.) production in Maryland. Within this tillage comparison, factors including corn planting date and post-plant cultivation were examined for optimizing this reduced-tillage organic corn production. Corn yield in roll-killed hairy vetch treatments that were planted to corn before 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, given the similarity in weed biomass after cultivation, fertility, moisture, and radiation across planting dates. In two years with supplemented soil weed seedbank populations, weed biomass was the major driver determining corn yield in these experiments; corn yield 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, roller-kill cover crop system can provide similar yields to those in a traditional tillage-based system, but also highlight the importance of maintaining a low weed seedbank to optimize corn yield.