EFFECTS OF FOLIAR UREA-NITROGEN AND TRIAZONE-NITROGEN, WITH AND WITHOUT BORON, ON COTTON

Optimal lint yield in recently released high-yielding upland cotton (Gossypium hirsutum L.) cultivars requires careful nutrient management. It is not known whether these cultivars are capable of responding to foliar nitrogen (N) and boron (B) fertilizer when conventional soil fertility practices are used. The objectives of this study were (i) to determine the responses of a high-yielding cotton cultivar to foliar N and B fertilizer and (ii) to compare two N sources when applied to foliage of cotton. A two-year field study was conducted with a factorial arrangement of three N treatments and two B treatments. Plants received foliar applications of the surfactant Tween 20 in H2O (check), or one of the following treatments plus surfactant: B (as H3BO3), triazone-N (24% of N as S-tetrahydrotriazone), triazone-N plus B, urea-N, or urea-N plus B. Leaf blade mineral element composition, lint yield, and fiber properties were determined. Averaged across years, lint yields were significantly higher in the check, both urea treatments, and the triazone plus B treatment than in the B only treatment. Foliar applications of either triazone-N or urea-N increased leaf blade N concentration but did not affect leaf blade B concentration. Foliar applications of B increased leaf blade B concentration but did not affect leaf blade N concentration. There were no N x B interactions on leaf blade N, leaf blade B, or on most fiber properties. For almost all variables, the effect of triazone-N was similar to that of urea-N. The results of this study suggested that augmenting standard cotton N and B fertility with foliar sprays was likely to increase leaf blade N and B concentrations but was unlikely to significantly effect yield or fiber properties.