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

Optimal lint yield in recently released high-yielding upland cotton (G ossypium hirsutum L.) cultivars requires careful nutrient management. It is not known whether these cultivars are capable of responding to f oliar nitrogen (N) and boron (B) fertilizer when conventional soil fer tility practices are used. The objectives of this study were (i) to de termine the responses of a high-yielding cotton cultivar to foliar N a nd B fertilizer and (ii) to compare two N sources when applied to foli age of cotton. A two-year field study was conducted with a factorial a rrangement 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 ure a-N plus B. Leaf blade mineral element composition, lint yield, and fi ber properties were determined. Averaged across years, lint yields wer e significantly higher in the check, both urea treatments, and the tri azone plus B treatment than in the B only treatment. Foliar applicatio ns 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, lea f 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 thi s study suggested that augmenting standard cotton N and B fertility wi th foliar sprays was likely to increase leaf blade N and B concentrati ons but was unlikely to significantly effect yield or fiber properties .