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Subsoiling and Potassium Placement Effects on Water Relations and Yield of Cotton
Author(s) -
Reeves D. Wayne,
Mullins Gregory L.
Publication year - 1995
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/agronj1995.00021962008700050011x
Subject(s) - loam , agronomy , soil water , fertilizer , subsoil , stomatal conductance , water potential , irrigation , environmental science , biology , botany , soil science , photosynthesis
Deep placement of K fertilizer may alleviate late‐season K deficiency of cotton ( Gossypium hirsutum L.) on soils adequate in surface soil K but low in subsoil K. This 2‐yr study in Alabama evaluated effects of deep tillage (in‐row subsoiling) and K fertilizer placement on yield, leaf K deficiency, soil water depletion, and stomatal conductance of cotton grown on a soil with a root‐restricting hardpan. The Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Kandiudults) soil tested medium for K in the top 15 cm and low at greater depths. Treatments were: (i) no K, no subsoiling; (ii) no K, subsoiled; (iii) surface application (84 kg K ha −1 ), no subsoiling; (iv) surface application, subsoiled; and (v) deep placement in the subsoiled channel. Surface application without subsoiling resulted in the greatest soil water content (0‐ to 80‐cm depth); deep placement, the lowest. Stomatal conductance was highest with no‐K, no subsoiling and lowest with K (surface or deep), subsoiled. There was no evidence of K or drought stress‐induced stomatal closure, and stomatal closure was not related to severity of leaf K deficiency. All three K treatments increased leaf K concentration at early bloom. Subsoiling without K fertilizer increased plant size and severity of leaf K deficiency; with surface K, subsoiling more than doubled total leaf area but did not affect leaf K deficiency. Within subsoiled treatments, leaf K deficiency was more severe with deep placement of K than with surface application. Subsoiling, especially with K fertilizer, maximized seed cotton yield in both years (avg. 3261 kg ha −1 ) but reduced stomatal conductance. Stomatal closure and premature leaf senescence are not the likely mechanism for late‐season leaf K‐deficiency in cotton. Although subsoiling was necessary to maximize cotton yields on this Coastal Plain soil with a root‐restricting hardpan, deep placement of K fertilizer was not superior to surface application.