A Comparison of Soil Sulfur Extraction Methods
- Quirine Ketterings *a,
- Chie Miyamotoa,
- Renuka Rao Mathurb,
- Kevin Dietzela and
- Sanjay Gamib
There are currently no field calibration data for interpretation of soil S tests in the U.S. Northeast and limited data elsewhere. Given the reduction in the S deposition rate during the past decade in the Northeast, it is important to evaluate the potential for soil testing as a tool for S management in the region. An incubation study was conducted to compare: (i) the accuracy and effectiveness of six S extraction methods to identify an increase in available S; and (ii) S detection in solution using inductively coupled plasma atomic emission spectroscopy (ICP–AES) at 182 nm with turbidimetric determination of S using BaCl2×2H2O and a spectrophotometer at 420 nm. The six extraction solutions were 1.0 mol L−1 NH4OAc, 0.016 mol L−1 KH2PO4, 0.01 mol L−1 Ca(H2PO4)2, 0.01 mol L−1 CaCl2, Morgan, and the Mehlich-3 solution. Four New York soils were treated with six S rates (0, 28, 56, 84, 112, 168 kg ha−1) applied as gypsum and incubated for 4 wk (in the dark, at room temperature, 75% of field capacity, four replications). Sulfur test results correlated with S fertilizer application for all extraction and detection methods; however, the 0.01 mol L−1 CaCl2 extraction with ICP–AES detection of S in solution was best correlated with S added (highest r2, smallest RMSE across all four soils), the regression equation had the largest slope, and this method showed the greatest consistency between the two detection methods. We conclude 0.01 mol L−1 CaCl2 extraction with ICP–AES detection of S is most promising and should be evaluated in field trials.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2011. Copyright © by the Soil Science Society of America, Inc.