Starter Fertilizer, Row Width, and Planting Date Effects on Corn Yield in North Central Iowa
Delayed planting or replanting of corn can result in significant yield losses. Recently, planting date studies in Iowa have shown 3% yield loss comparing mid-May planting dates with late April planting dates and 20-30% yield loss comparing June planting dates with late April planting dates. These yield losses can be partially attributed to the hastened vegetative development from increased accumulation of thermal units at later planting dates, which contribute to lessened capture of light resources and thus less carbon fixation. In Iowa, it has been shown that starter fertilizer can increase the early growth of corn from stage V3 to V8. Narrow row spacing will also improve light interception during early vegetative development. During the 1999 and 2000 growing seasons, the effects of planting date, row spacing, and starter fertilizer on corn yield were evaluated. The objective of this study was to determine whether the use of starter fertilizer and row spacing at later planting dates would reduce the associated yield loss by improving early resource capture.