C. W. Bednarz, N. W. Hopper, and M. G. Hickey

Foliar fertilizers have become one of the many inputs used in cotton (Gossypium hirsutumL.) 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:  (i) lint and seed yields, (ii) plant dry weight, (iii) plant leaf area, and (iv) leaf nitrogen concentration.  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, thermix, 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 micronutritnets), and 4(8-8-8 with micronutrients) were commercial products and were applied in compliance with 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 wk after matchead square.  One week after each treatment application.  10 plants were removed from each plot and divided into three nodal horizons:  (i) from node 6 to node 9, (ii) from node 10 to node 13, and (iii) node 14 and above.  Leaf total and nitrate N concentrations were determined by these nodal horizons.  Also, at 1, 5, and 9 wk after matchead square, plant leaf areas and dry weights were determined.  Lint yields were determined after a killing freeze in 1990 and after crop termination in 1991.  Feed grade urea increased leaf total N concentrations during 1990, but these results were not repeated in 1991.  Urea also increased leaf nitrate N during both growing seasons.  However, plant leaf are and dry weight, and lint and seed yields were not significantly affected by foliar fertilizers.  Cost-benefit analyses were not conducted due to the lack of a significant yield response from foliar fertilizers.  We conclude none of the costs associated with foliar fertilization will be recovered in net returns.

Published in J. Prod. Agric.  11:80-84 (1998).