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Foliar Feeding of Cotton: Evaluating Potassium Sources, Potassium Solution Buffering, and Boron
Author(s) -
Howard Donald D.,
Gwathmey C. Owen,
Sams Carl E.
Publication year - 1998
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1998.00021962009000060004x
Subject(s) - loam , potassium , chemistry , phosphorus , malvaceae , silt , agronomy , boron , fertilizer , gossypium hirsutum , soil water , environmental science , soil science , biology , paleontology , organic chemistry
Foliar applications of K may be used to supplement soil applications to maximize yields of cotton ( Gossypium hirsutum L.). Response to foliar K applications may be improved by choice of K source, buffering the spray solution, or applying K with B. Research was conducted on a Collins silt loam (coarse‐silty, mixed, acid, thermic Aquic Udifluvents) and on a Memphis silt loam (fine‐silty, mixed, active, thermic Typic Hapludalfs) to evaluate KNO 3 , K 2 SO 4 K 2 S 2 O 3 , and KCl as K sources. A second study evaluated foliar KNO 3 and K 2 SO 4 solutions applied unbuffered and buffered to pH 6 and 4 on cotton K nutrition and yield. Foliar K in both studies was applied at 4.1 kg K ha −1 per application. A third study evaluated combinations of soil‐applied and foliar‐applied B and K. Foliar treatments were applied in 93.5 L ha −1 water at early flower or 2 wk after and repeated on a 9‐ to 14‐d interval between the four applications. Yields from the four K sources averaged 10% higher than the untreated check and yields with KNO 3 were 4% higher than the other K sources. Buffering two K source solutions to pH 4 resulted in 10% higher yields than the check or unbuffered K solutions. Adding a surfactant (ethoxylated alkyl aryl phosphate esters) to KNO 3 resulted in 5% higher yields then the check. Compared with untreated check yields, soil‐applied B at 0.56 kg B ha −1 increased yields by 6%, four foliar applications of 0.11 kg B ha −1 increased yields by 8%, and four foliar applications of 0.11 kg B plus 4.1 kg K ha −1 increased yields by 13%. Foliar K solution buffering and/or the inclusion of foliar B are relatively inexpensive ways of improving yield response. Based on yield increases in this study, these treatments should return 8 to 10 times the product costs.