Effect of Timing and Rate of Application of Urea and ESN on Cotton - WITHDRAWN

Supplemental N fertilization is required for production of economically sustainable cotton yields in Arkansas and the rest of the midsouth. Soil and fertilizer N can be lost from cotton root zone by runoff, leaching, and denitrification.  Improving N use efficiency will increase profit margins and reduce potential environmental risks. Currently the University of Arkansas  recommends split application of a total of 110 to 120 lb N/acre for irrigated cotton. However, split application requires additional planning, labor, and farm equipment.  Using an slow release N fertilizers is an strategy that needs to be evaluated. Nitrogen treatments consisted of: a no N (0 N) control, a two way split application of 110 lb/acre urea-N (standard practice), a single application of 60 lb/acre of  urea-N, a two way split application of 90 lb/acre urea-N, a single application of 60 or 90 or 100 lb/acre of  ESN-N.  At one site we randomly selected 12 plants per plot, measured their main stem height from cotyledonary node to the terminal bud, and the number of the main-stem nodes above the top white flower (NAWF) at 79 and 104 DAP.  At the other site we measured the same plant growth parameters at 73 and 85 DAP.  The two center rows of cotton in each plot were harvested. Analysis of variance (ANOVA) was performed to evaluate the effect of N treatment on plant height, NAWF, and seedcotton yield by using the GLM procedures of SAS.   When appropriate, significant differences among the means were separated by the least significant difference (LSD) test with significance interpreted at the 0.10 level.  The effect of treatments on various plant growth parameters will be presented and discussed.