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Profit‐maximizing potassium fertilizer recommendations for corn and cotton
Author(s) -
Oliver Kimberly,
Popp Michael P.,
Slaton Nathan A.,
Drescher Gerson Laerson,
Roberts Trenton L.
Publication year - 2022
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 - 10.1002/agj2.21205
Subject(s) - fertilizer , agronomy , potash , yield (engineering) , mathematics , oryza sativa , potassium , human fertilization , chemistry , biology , biochemistry , materials science , gene , metallurgy , organic chemistry
Whereas K fertilization is necessary to maximize corn ( Zea mays L.) and cotton ( Gossypium hirsutum L.) yields in soils with sub‐optimum K availability, maximizing yield is rarely profit‐maximizing. Estimating the tradeoff between yield and fertilizer cost using current soil‐building and/or yield‐maximizing rate recommendations vs. profit‐maximizing fertilizer‐K rates (KR * ) provides insights for producers. Thirty‐nine and 24 fertilizer‐K rate trials were used to estimate respective corn and cotton yield response based on soil‐K availability (SK). Using a field's SK, yield potential, yield response to fertilizer‐K, crop price, and fertilizer‐K cost, KR * were calculated over the past 10 yr. Averaging over that period, using KR * at SK of 75 and 60 mg K kg –1 (a) reduced fertilizer‐K rate by 10 and 38 kg K ha –1 , respectively, (b) decreased yield by 53 and 32 kg ha –1 , respectively, and (c) increased profitability by US$1.75 and $34.24 ha –1 , respectively, in comparison to current recommendations for corn. At SK of 75 and 110 mg K kg –1 , cotton profitability at KR * vs. current recommendations rose by $11.54 to $25.95 ha –1 , respectively, using 36 and 101 kg K ha –1 more fertilizer, respectively, which led to 27 and 73 kg ha –1 greater yield, respectively. As with prior studies for rice ( Oryza sativa L.) and soybean [ Glycine max (L.) Merr.], corn results suggest using less fertilizer than currently recommended, whereas for cotton, strong yield response to fertilizer‐K and relatively high crop price justified KR * that were above currently recommended rates. A spreadsheet‐based decision tool is online to offer this insight to producers and crop consultants.