Starter Fertilizer for Managing Cover Crop‐Based Organic Corn

CORE IDEAS: Grass and legume cover crops are combined for weed and fertility management. A cereal rye and hairy vetch mixture provided more than 7500 kg ha⁻¹ biomass. Additional fertility is necessary to maximize cover‐crop based organic corn yield. Subsurface banding feather meal is an option to increase organic corn yield. If cover crop biomass is low, providing adequate N fertility is critical for yield. Grass and legume cover crops are combined in mixtures to provide both weed and N fertility management in organic production; however, additional N fertility may be required to maximize corn yield. The research was conducted in Beltsville, MD; Kinston, NC; and Salisbury, NC; from 2012 to 2014 to evaluate the effect of starter fertilizer source and application method on weed competition and grain yield in cover crop‐based, organic corn production. Fertility treatments included high rate broadcast poultry litter (Plant available nitrogen [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. 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 before corn planting. Cover crop biomass more than 7500 kg ha⁻¹ provided excellent weed suppression. 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 corn 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.