COTTON RESPONSE TO STARTER FERTILIZER PLACEMENT AND PLANTING DATES

Effect of planting date on cotton (Gossypium hirsutum L.) response to side-banded starter fertilizer has not been well documented. Consequently, field studies were conducted in four North Carolina environments to examine the response of cotton to placement of starter fertilizer at three planting dates. Cotton planted prior to 5 May (Early), mid-May (Mid), and late-May (Late) on a Norfolk loamy sand (fine-loamy, siliceous, and thermic Typic Kandiudults) and Craven fine sandy loam (clayey, mixed, thermic Aquic Hapludults) received broadcast or side-banded applications of ammonium polyphosphate at the rate of 17 and 57 kg ha-1 of N and P2O5, respectively. Fertilizer placement had minor effects on plant population. Planting period effects on plant population could not be attributed to heat unit accumulations. Flower production during the first 3 wk of bloom varied with planting period and environment. Mid- and late-planting decreased average lint yields across the four environments by 31 and 50%, respectively. Lint yield was increased 9% by side-banded fertilizer placement. Significant planting period X fertilizer placement interactions were not observed for plant population, flower production, and lint yield. This indicates that applying side-banded starter fertilizer can benefit producers irrespective of planting date.