Inconsistent Responses of Corn to Seeding Rates in Field-Scale Studies

Corn (Zea mays L.) seeding rates have increased because new hybrids lodge less, have improved drought tolerance, and may respond to higher rates in narrow rows. Farmer-researcher partnerships were formed to evaluate two hybrids at two 0.76-m-row sites and a twin-row site at four seeding rates (61,750, 74,100, 86,450, and 98,800 kernels ha(-1)) and a narrow-row site (0.51-m rows at similar to 5000 more kernels ha(-1) across seeding rates) in field-scale studies in 2011 and 2012 in New York. Partial budget analyses were conducted to aid in future seeding rate decisions based on 2011-2012 market grain prices (US$ 265.76 Mg-1) in New York and grower seed (US$ 225 per 80,000 kernels) costs, in addition to drying and hauling costs. Yields averaged 11.8 Mg ha(-1) in 2011 and 10.5 Mg ha(-1) in 2012, but yield and relative profit responded inconsistently to seeding rates across sites, between hybrids, and between years at the narrow-row site. Maximum relative profit exceeded the recommended seeding rate of 74,100 kernels ha(-1) at the twin-row site (76,000 kernels ha(-1)), at the narrow-row site in 1 yr (85,000-95,000 kernels ha(-1)) but not at 0.76-m-row sites. Lack of consistent responses to seeding rates is probably related to dry July conditions in both years, contributing to decreases of 4 to 5 kernels plant(-1) and 0.5 to 1 mg in kernel weight for each 1000 kernel ha(-1) seeding rate increase at most sites. Based on these field-scale studies, recommended seeding rates in New York will not change.