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Influence of Fertilizer Application Nonuniformity on Crop Response
Author(s) -
Ndiaye J. P.,
Yost R. S.
Publication year - 1989
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/sssaj1989.03615995005300060043x
Subject(s) - fertilizer , zoology , human fertilization , coefficient of variation , yield (engineering) , field experiment , mathematics , brassica , agronomy , chemistry , biology , statistics , physics , thermodynamics
Levels of nonuniformity in K fertilizer application were established in a field experiment on a K deficient soil. Measures of uniformity of fertilizer distribution (UCF) were calculated from the coefficient of variation (CV) of K application (UCF = 1 − CV/100). The structure of spatial dependence of exchangeable soil K was used to estimate the proportion of a given experimental plot which should be below a specified threshold of exchangeable K. Fertilizer requirements were estimated on the basis of the proportion of the region that was deficient. If deficient areas were identified in the field, then variable rates of fertilization could be applied. The response of chinese cabbage ( Brassica oleracea L. Chinensis) to K application was strongly affected by the uniformity of fertilizer distribution. Maximum yield decreased 9.5% with nonuniformity of fertilizer distribution. Amounts of K associated with 95% maximum yield were 97, 113, and 444 kg K ha −1 for UCF values of 1.0, 0.42, and −0.02, respectively. Corresponding tissue K concentrations associated with 95% maximum yield were 3.5, 3.8, and 4.0%. Increased variation in exchangeable K from CV = 44.1% to CV = 96.6% resulted in critical levels of soil K of 0.28 and 0.73 cmol c ha −1 , respectively.