Nitrogen fertilization and yield of cotton in ultra-narrow and conventional row spacings

Nitrogen fertilizer requirements of ultra-narrow row (UNR) cotton (Gossypium hirsutum L.) are not well established, and lint yield of UNR relative to conventional-row (CR) cotton has been variable. Objectives of this study were to compare UNR and CR N requirements based on lint yield, fiber quality, and plant architecture, and to compare the yield potential of UNR and CR cotton. The location was the Texas Agricultural Experiment Station Farm, Burleson County, TX. Treatments were N fertilizer rates of 0, 50, 101, and 151 kg ha(-1) and row spacings of 19, 38 (both UNR), and 76 cm (CR). By design, per-hectare plant populations were greatest in 19- and least in 76-cm row spacings. Plots were hand harvested. Reductions in row spacing decreased plant height, main stem nodes plant(-1), and subset (first position bolls at nodes 6-10) individual boll weight. Greater N increased plant height, main stem nodes plant(-1), and both whole-plant and subset individual boll weight. Lint percentage was increased by reduction in row spacing and not affected by N. Treatment effects on fiber quality were limited. Lint yield did not differ among row spacings. Significant increases in lint yield occurred with each increase in N, suggesting that the optimal N rate was not surpassed. Nitrogen by row spacing interaction on lint yield was not significant, implying a similar response of each row spacing to N over the fertilizer rates tested. The N fertilizer requirements of UNR do not appear to be lower than those of CR cotton.