Starter fertilizer for managing cover crop-based organic corn

Authors: VANN, RACHEL - North Carolina State University; REBERG-HORTON, S. CHRIS - North Carolina State University; Mirsky, Steven; POFFENBARGER, HANNA - Iowa State University; ZINATI, GLADDIS - Rodale Institute; MOYER, JEFFREY - Rodale Institute

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2017
Publication Date: 9/7/2017
Citation: Vann, R.A., Reberg-Horton, S., Mirsky, S.B., Poffenbarger, H.J., Zinati, G.M., Moyer, J.B. 2017. Starter fertilizer for managing cover crop-based organic corn. Agronomy Journal. 109:2214-2222.

Interpretive Summary: Reducing tillage in organic grain production is seen as an important strategy to reduce production risk for producers, lower labor which allows organic grain producers to scale-up their operations, and attract soil conservation minded conventional producers to transition to organic. Weed control and N availability limit yield in cover crop-based organic rotational no-till corn production. Grass and legume cover crops are combined in mixtures to provide both weed and fertility management; however, additional fertility may be required to maximize corn yield. Therefore, research was conducted at Beltsville, MD; Kinston, NC; and Salisbury, NC; from 2012-2014 to evaluate the effect of starter fertilizer source and application method on weed competition and grain yield in cover crop-based, organic rotational no-till corn production. Results from this study indicate that starter fertilizer is necessary to maximize corn yield at sites with low initial soil nitrogen levels. When nitrogen was limited, rates of 70 kg ha-1 of plant available nitrogen was required to achieve maximum yields. Decisions regarding additional fertility will need to be dynamic based on site history, cover crop biomass production, and the ability to broadcast poultry litter. This work will help growers make decisions about fertility management in organic corn production and provides more information to producers and researchers on integrated green and animal manure based fertility management.

Technical Abstract: Weed control and N availability limit yield in organic corn production. Grass and legume cover crops are combined in mixtures to provide both weed and fertility management; however, additional fertility may be required to maximize corn yield. Research was conducted at Beltsville, MD, Kinston, NC, and Salisbury, NC, from 2012-2014 to evaluate the effect of starter fertilizer source and application method on weed competition and grain yield in cover crop-based, organic rotational no-till corn production. Fertility treatments included high rate broadcast poultry litter (PAN=160 kg ha-1), low rate broadcast poultry litter (PAN=72 kg ha-1), subsurface banded feather meal (PAN=80 kg ha-1), subsurface banded poultry litter (PAN=12 kg ha-1), and no starter fertility. Both weedy and weed-free conditions were maintained across all fertility treatments. A cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) mixture was established in the fall and was terminated using a roller-crimper prior to corn planting. Cover crop biomass in excess of 7,500 kg ha-1 provided excellent weed suppression in five of six environments. In a combined analysis of five environments, corn N content and yield followed the same pattern of high rate broadcast poultry litter>low rate broadcast poultry litter=subsurface banded feather meal>subsurface banded poultry litter=no starter fertility. Results from this study indicate that starter fertilizer is necessary to maximize corn yield in cover crop-based organic rotational no-till production and that decisions regarding additional fertility will need to be dynamic based on site history, cover crop biomass production, and the ability to broadcast poultry litter.