Field‐Scale Studies Show Site‐Specific Corn Population and Yield Responses to Seeding Depths

Corn (Zea mays L.) seeding depth recommendations typically range from 3.8 to 5.1 cm, but few studies have been conducted in recent years. We conducted field‐scale studies on four farms at four equally spaced seeding depths (2.5–6.4 cm) in New York in 2013 and 2014 to validate seeding depth recommendations across different soil conditions. Seeding depth affected corn populations and yield in 6 of 8 site‐years but optimum seeding depth differed across sites and years within sites. Yield responses to seeding depth were small on well‐drained silt loams with reduced tillage (∼3% advantage at 3.8 vs. 2.5 and 5.1 cm in 2013 and no difference in 2014), and on somewhat poorly drained silty clay loams under no‐till (∼5.5% difference with maximum yields predicted at ∼4.2 cm in both years). Yield responses to seeding depth were larger on a somewhat poorly drained silt loam with moldboard plowing (9–15% advantage for 6.4 vs. 5.1 and 3.8 cm, respectively; maximum yields predicted at >5.78 cm in both years). On somewhat poorly drained silt loams with reduced tillage, populations had a positive quadratic response (maximum populations predicted at 5.45 cm) and yield had a positive linear response in 2013, but plant populations had a negative linear response and yield had no response in 2014. Weather conditions after planting affected yield responses inconsistently, but the data indicate that seeding depths should probably range from 3.8 to 5.1 cm on silty clay loams and from 3.8 to 6.4 cm on silt loams.