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Exchangeable Soil Potassium as Influenced by Seasonal Cropping and Potassium Added in Crop Residues
Author(s) -
Grimes Donald W.,
Hanway John J.
Publication year - 1967
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1967.03615995003100040024x
Subject(s) - potassium , crop rotation , agronomy , chemistry , crop residue , crop , soil water , environmental science , soil science , biology , ecology , agriculture , organic chemistry
Detailed sampling of soils and crops from three long‐term field experiments permitted evaluation of the seasonal depletion of exchangeable soil K and the influence of K added as crop residue. Exchangeable soil K was markedly reduced during the growing season by a growing crop. For corn ( Zea mays L.), the regression of the decrease (spring to fall) in exchangeable K (pp2m) on the initial (spring) level of exchangeable K was characterized by a quadratic relationship, Ŷ = −23.5 + 0.62X − 0.00072X 2 (r 2 = 0.78**). Increases in the exchangeable K from fall to spring were directly related to K additions in crop residues. Within a single crop rotation, the exchangeable K increased as a result of K additions from corn residues and declined when meadow was grown. When maintained in a field moist condition before the determination of exchangeable K, reduced levels of exchangeable K resulting from cropping were not restored by release of non‐exchangeable K. When the exchangeable K was reduced to a very low level, however, nonexchangeable forms of K were released to the exchangeable form to maintain a “minimal” level of exchangeable K.