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Evaluation of Various Extractants for Available Soil Sulfur
Author(s) -
Hoeft R. G.,
Walsh L. M.,
Keeney D. R.
Publication year - 1973
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/sssaj1973.03615995003700030027x
Subject(s) - soil water , chemistry , yield (engineering) , tonne , subsoil , soil test , organic matter , mathematics , soil science , zoology , environmental science , biology , materials science , organic chemistry , metallurgy
The S status of 49 Wisconsin soils was evaluated in field studies using alfalfa ( Medicago sativa ) as the test crop. The effectiveness of six soil S extractants for predicting yield and S uptake response to applied S were evaluated by means of correlation analyses. The best extractant, considering all dependent variables and the S range, mean and standard deviation for each procedure, was 2 N HOAc containing 500 ppm P as Ca(H 2 PO 4 ) 2 · H 2 O [Ca(H 2 PO 4 ) 2 ‐HOAc]. The correlation between extractable S and response to applied S was not improved by inclusion of percent organic matter, percent sand, or subsoil SO 4 ‐S in the regression equation. However, inclusion of soil pH with extractable S did significantly improve the prediction of S response. The best equation for prediction of yield response to applied S in the field was: Yield response (metric tons/ha) = 50.81 − 7.22 pH − 8.19 S + 1.171 (pH × S) + 0.167 (S) 2 − 0.00341 (pH × S) 2 where S is the ppm of S extracted with Ca‐(H 2 PO 4 ) 2 ‐HOAc. Significant response to applied S would be expected on soils having a calculated yield response of 0.40 metric tons/ha or greater when extractable S is between 6 and 10 ppm S. Soils testing less than 6 ppm would be expected to respond and those testing greater than 10 ppm S would not be expected to respond to application of S, regardless of the calculated response value. Use of the regression equation and the limits of 6 and 10 ppm S resulted in correct prediction of S response at 77.6% of the field sites.