|Wells, M - North Carolina State University|
|Reberg-horton, S - North Carolina State University|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2015
Publication Date: 1/14/2016
Citation: Wells, M.S., Reberg-Horton, S.C., Mirsky, S.B. 2016. Planting date impacts on soil water management, plant growth, and weeds in cover-crop-based no-till corn production. Agronomy Journal. 108:162-170.
Interpretive Summary: A cover crop-based organic rotational no-till corn production system combines the soil conservation practices associated with conventional no-till with the soil building practices associated with organic crop production. This crop production system relies on growing high levels of cover crop biomass for weed suppression. However, delaying cover crop termination to allow for cover crop biomass accumulation to levels acceptable for weed control can also lower soil water levels to unacceptable levels. A 4-site year study was conducted to evaluate the effects of corn planting timing after roll-crimping a cover crop mulch, on soil moisture, crop stand, weed pressure and corn yield. Spring precipitation adequately recharged the soil profile after cover crop termination. Therefore, timing of planting corn following cover crop termination is dependent on adequate sping precipitation events that off-set transpiration losses from the cover crop. Farmers should time cover crop management and planting based on precipitation forecasts. This work will provide producers with more evidence that high biomass cover crops can be used within their production systems in regions with adequate spring precipitation.
Technical Abstract: Low input and organic farmers are increasingly utilizing cover crop mulches in maize production. Many farmers are delaying planting corn into these high residue environments to allow greater growth of the cover crop to maximize nitrogen fixation and improve mechanical termination with roller crimpers. During the late spring, 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-crimping a cover crop mulch, on soil moisture, crop stand, weed pressure and corn yield. Legume/grass cover crop mixtures were compared including: winter pea (Pisum sativum ssp. arvense) (P), and ‘AU Early Cover’ hairy vetch (Vicia villosa ROTH) (V) 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 no cover crop mulch. The corn planting date across all 4 site-years did not affect weed biomass; however, weed coverage at Salisbury (2012) was affected by planting date. Cover crop treatments yielded equivalent to the weed-free no-till with no cover crop mulch in 2011. However, despite high biomass production from P and V mulches, in-row weeds did escape control in in the cover crop treatments compared to the weed-free control plots, at 3 of the 4 site-years. These results support the viability of roll-killed cover crop mulches as an alterative to existing organic corn systems that rely solely on intensive tillage for weed management.