Effects of Nitrogen Application Timing On Cotton Under Different Planting Dates

It is essential to develop innovative approaches that can manage N more efficiently to increase grower profitability due to substantially increased N prices. The objective of this study was to determine the optimal N application timings for high-yielding cotton cropping systems in Tennessee. A field small-plot experiment was conducted at Jackson in 2011 and 2012. Four N timing treatments (pre planting, at planting, early side dress, and late side dress) were evaluated under three cotton planting dates (early, normal, and late) in a randomized complete block split plot design with four replications. The following data were collected on a split plot basis each year: Soil nitrate content before cotton planting and after cotton harvest; canopy normalized vegetation index readings, leaf chlorophyll meter readings, plant height, number of main-stem nodes, average internode length, and leaf N concentration at early square, early bloom, mid bloom, and peak bloom; number of main stem nodes above the uppermost white flower at fruiting position 1 at early bloom, mid bloom, and peak bloom; bolls from the first to fifth lateral fruiting position on fruiting branches at harvest; boll number per plant and average seed cotton weight per boll at harvest; lint yield at harvest; gin turnout an fuzzy seed index; fiber quality properties including fiber strength, elongation, UHM length, uniformity, and micronaire; and nitrogen concentration in cotton seed. Additionally, temperature and rainfall data were recorded during the growing season each year. The major results of this study will be presented and discussed.