ABSTRACT

Improved fertilizer N management and delivery systems for cotton (Gossypium hirsutum L.) in the Eastern Coastal Plain of the United States will decrease the potential for ground water contamination by nitrates. An experiment was conducted in 1991 and 1992 to determine the effect of buried microirrigation and N management on plant and soil N status as well as cotton yield. Water treatments in the study were irrigated (buried microirrigation tubing) and nonirrigated. Nitrogen treatments were 112 kg N/ha at the seventh true leaf stage, five weekly applications of 22 kg N/ha beginning at seventh true leaf stage, and 11 kg N/ha applications when the computer simulation model GOSSYMCOMAX (GC) predicted N deficiency (67 kg/ha were applied in both years). A preplant application of 22 kg N/ha was broadcast across the experimental area prior to planting cotton. All post emergence N applications were made through microirrigation tubing. Nonirrigated lint yields were 1740 and 588 Kg/ha in 1991 and 1992, respectively. Lint yields averaged 1716 and 696 in 1991 and 1992, respectively, for the irrigated treatments. No differences in lint yield were found among the N management treatments with irrigation. Yet, the GC treatment received 45 kg/ha less N.