Effects of foliar fertilization of texas southern high plains cotton: Leaf phosphorus, potassium, zinc, iron, manganese, boron, calcium, and yield distribution1

Abstract

Foliar fertilizers are often used in cotton (Gossypium hirsutum L.) production systems across the U.S. Cotton Belt. Their usefulness, however, in producing high yielding, high quality cotton remains to be resolved. This study was conducted to determine the effects of foliar fertilizers on cotton leaf phosphorous (P), potassium (K), zinc (Zn), iron (Fe), manganese (Mn), boron (B), and calcium (Ca) concentrations and yield distribution. During the 1990 growing season, this study was conducted at the Texas Tech University Research Farm east of New Deal, TX on a Pullman clay loam (fine, mixed, superactive thermic, Torrertic Paleustoll). Six foliar treatments were incorporated into a randomized complete block design with six blocks. Treatments 2(15–2–0 with Ca), 3 (8–32–5 with Mn, Fe, Zn, and B), and 4 [8–8–8 with Mn, Fe, Zn, B, and copper (Cu)] were commercial products and were applied according to their manufacturers recommendations. Treatments 5 and 6 (46–0–0) were applied at various rates. During the 1991 growing season, this study was conducted at an on‐farm location northeast of Petersburg, TX. The soil at this location was also a Pullman clay loam. The same six foliar treatments were incorporated into a randomized complete block design with four blocks. Foliar treatments were applied during both growing seasons at 0, 2, 4, 6, and 8 weeks after square initiation. One week after each treatment application, ten plants were removed from each plot and divided into three nodal horizons: (1) from node six to node nine, (2) from node ten to node thirteen, and (3) node fourteen and above. Leaf nutrient concentrations were determined by these nodal horizons. Numbers of first and second position fruit per plant were also determined within these nodal horizons. Leaf Zn, Fe, Mn, and B were increased by one of the commercial products in this investigation. However, none of these elements were deficient in the untreated plots and the observed increases were beyond the plant required concentrations. Cost‐benefit analyses were not conducted due to the lack of a significant yield response from the foliar fertilizers. We conclude that none of the costs associated with foliar fertilization will be recovered in net returns.