Pioneer Long-Term Corn Planting Date Studies
Pioneer Agronomy Sciences has conducted planting date studies for over 30 years. This article reports results from 18 seasons across central, north central, north, and far north locations of the Corn Belt (Figure 1). Planting dates ranged from early April to mid-June. Several hybrids were included in each maturity group so that true maturity responses could be measured, rather than just specific hybrid responses.
Figure 1. Central (red), north-central (orange), northern (green), and far-northern (blue) research sites for Pioneer planting date studies from 1987-2004.
The experimental design was a randomized complete block in a split-plot arrangement with planting date as whole plot and hybrid as sub-plot with four replications. The plots were four rows wide and harvest data were collected from the center two rows of the plot. To allow for continued hybrid maturity development and grain drying, the later planting dates were harvested separately at many locations.
Adjusted gross income/acre was calculated as gross income at a corn price of $5.00/bu minus drying costs and discounts for low test weights. Drying costs were calculated based on 4 cents/bu for each point of moisture above 15%. The test weight discount schedule used for this analysis is shown in Table 2; however, discount rates vary among corn buyers. (Test weight discounts are more relevant to grain delivered wet to a buyer versus corn dried on the farm, as test weight increases significantly as moisture is removed by field or artificial drying.)
Table 2. Discount rates for low test weight corn.