ABSTRACT
Cotton (Gossypium hirsutum L.) in the midSouth USA is grown at row spacing of 30 to 40 inches. Most agronomic research has been conducted at row spacings of 38 to 40 inches. The objective of this research was to compare the performance of cotton in 30 and 40inch row spacings using different N rates and plant population densities. Field studies were conducted for four years (19921995) on Sharkey clay at the Northeast Research Station near St. Joseph, LA. Each year a factorial experiment was planted with two row spacings (30 and 40 inches), two irrigation regimes (irrigated and nonirrigated), four plant densities (26000, 39000, 52000 and 65000 per acre) and four N rates (60, 90, 120 and 150 lb per acre). Irrigation increased yield in only one of four years. Lint yields were higher in the 40inch row spacing in two of the four years and were not affected by row spacing in the other two years. Averaged across years, irrigation, N rate and plant density, the 40inch rows had a lint yield advantage of 54 pounds per acre. The row spacing x N rate and row spacing x plant density yield interactions were significant. The optimal N rate for cotton in 30inch rows was 120 pounds per acre and for 40inch rows was 90 pounds per acre. Optimal plant density for 30inch rows was 26000 per acre and for 40inch rows was 39000 per acre. Results demonstrate that little yield difference should be expected between 30 and 40inch row spacings and that closer row spacing requires higher N rates for maximum yield.
