Planting date impacts on soil water management, plant growth, and weeds in cover-crop-based no-till corn production

Low input and organic farmers are utilizing cover crop mulches in corn (Zea mays L.) production. Corn planting is typically delayed to improve the efficacy of mechanical termination with roller-crimpers. During the late spring, as cover crops are allowed to grow to maximize biomass production, soil moisture reserves can become depleted, thereby directly impacting early season growth of the subsequent cash crop. A 4 site-year study was conducted in North Carolina (Goldsboro, Kinston, and Salisbury) to evaluate the effects of timing of corn planting after roller-crimping a cover crop mulch, on soil moisture, crop stand, weed pressure and corn yield. Two cover crop mixtures were compared: winter pea [P/R, Pisum sativum ssp. arvense (L.) Poir.], and hairy vetch (HV/R, Vicia villosa Roth) were both mixed with cereal rye (Secale cereale L.). Both cover crop treatments produced biomass greater than 7000 kg ha^–1 dry matter at all sites. Delayed planting after the cover crops were rolled-crimped did not enhance the soil volumetric water content (VWC) within the upper 10 cm. However, at Kinston in 2012, the VWC was 23% greater in the HV/R when compared to P/R and no-mulch treatments. The corn planting date across all 4 site-years did not affect weed biomass. Corn (2011) in the cover crop treatments yielded equivalent to their weed-free notill without cover crop mulch counterparts. These results support the viability of rolled-crimped cover crop mulches as a lower energy input alternative to existing organic corn systems that rely solely on intensive tillage for weed management.