Influence of polyaspartic acid on growth and yield of cotton

Abstract

Nitrogen fertilization is normally required by upland cotton (Gossypium hirsutum L.) for optimism yields. Increasing the efficiency of applied N fertilizer and other nutrients would aid in cotton production. Polyaspartic acid (PA), a long-chained, negatively charged polymer, is marketed as a nutrient absorption enhancement material. The product purportedly increases nutrient uptake by increasing root and root hair development. A study was conducted in 1996 and 1997 in Burleson County, Texas to evaluate the effects of various combinations of PA and N on cotton growth and yield. The study design was a factorial with main effects being N and PA rates. The N treatments were 34, 101 and 168 kg ha⁻¹, applied as NH₄NO₃, side-dressed in-furrow at the 2- to 3- leaf stage and before planting in 1996 and 1997, respectively. In both years, PA was applied at early bloom at rates of 0, 4.7, 9.4, and 18.7 L ha⁻¹ with 2.3 L ha⁻¹ of the desired rate being applied with the N fertilizer at planting. Total fruit, fruiting sites, fruit distribution, height, member of nodes, and percent fruit abscission were not affected by any PA treatment.Furthermore, no differences in yield were observed for any PA treatment.However, N rates of [] 101 kg ha⁻¹ increased the vegetative and reproductive growth of cotton as well as lint yield both years. A foliar study was also conducted in 1997 in Burleson County, Texas and Swisher County, Texas to examine the effect of different rates of PA applied with and without a micronutrient mix. . Treatments included a control, micronutrient mix, 4.67 L PA ha⁻¹, 9.35 L PA ha⁻¹ micronutrient plus 4.67 L PA ha⁻¹ and micronutrient plus 9.36 L PA ha⁻¹. The micronutrient mix alone and micronutrients plus 9.36 L PA ha⁻¹ increased lint yields over all other treatments, with micronutrient plus 9.36 L PA ha⁻¹ yielding significantly more than the micronutrient mix alone. However, no differences in plant structure or boll distribution were observed. Although not examined, it was speculated that an increase in boll size may have contributed to the elevated yields.