Maize Performance As Determined By Planting Date In a Cover Crop-Based Rotational No-Till Production System.

Weed management in organic corn production relies heavily on frequent and intensive primary and secondary tillage practices, which have the potential to negatively impact the environment.  However, new conservation tillage practices such as the use of roll-killed cover crops can mitigate the derivative effects of intensive tillage.  To achieve optimum corn yield in a cover crop-based roll-crimp system that does not rely on mineral fertilizer, the cover crop must be managed to achieve maximum biomass potential for both weed and fertility management.  Cover crop termination must be delayed until the cover crop reaches the critical minimal maturation, which continues into mid-May to early June.  During this time frame, soil moisture reserves are continuously depleted, and could provide a negative feedback to the subsequent cash crop.  A 4-site year study was conducted in North Carolina to evaluate the effects of corn planting timing after roll-kill on  soil moisture, crop stand, weed pressure and corn yield. In addition, this trial was conducted using two different grass: legume mixtures; Austrian winter pea (Pisum sativum ssp. arvense) (P), and AU ‘Early’ hairy vetch (Vicia villosa ROTH) (V) were both mixed with Wrens Abruzzi rye (Secale cereale L.).  Both cover crop treatments produced an excess of 7000 kg ha^-1 dry matter (DM) at all 4-sites. Delayed planting after roll-kill did not enhance the soil water content; however, at Kinston (2012), the soil water content was 23% greater in the hairy vetch (V) when compared to winter pea (P) and conventionally tilled treatments.  The corn planting date across all 4 site-years did not affect weed control.  Cover crop treatments yielded equivalent to their weed-free conventionally tilled counter parts in 2011; however, despite high biomass production from pea and vetch, in-row weeds did escape control in the CC-HB treatments, at 3 of the 4 site-years when compared to the CC+HB treatments.  These results support the viability of roll-killed cover crop mulches as an alternative to existing organic corn systems that rely solely on intensive tillage for weed management.