A Comparison of Soil Sulfur Extraction Methods

Abstract

Ihere 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 imporunt 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 1S2 nm with curbidimetric determination of S using BaCl2x2H2O and a spectrophotometer at 420 nm. The six extraction solutions were 1.0 mol L"' NH^OAc, 0.016 mol L"' KHjPO^, 0.01 mol L"' CaiHjPO^jj, 0.01 mol L"' CaCI^, Morgan, and the Mehlich-3 solution. Four New York soils were treated with six S rates (0,28,56,84,112,168 kg ha~') applied as gypsum and incubated for 4 wk (in the dark, at room temperature, 75% ofñeld capacity, four replications). SulRir test results correlated with $ fertilizer application for all extraction and detection methods; however, the 0.01 mol L~' CaClj extraction with ICP-AES detection of S in solution was best correlated with S added (highest r^, 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~' CaClj extraction with ICP-AES detection of S is most promising and should be evaluated in field trials. Abbreviations: ICP-AES, inductively couple plasma atomic emission spectroscopy; OM, organic matter.

A Simple Method for Estimating Effective Cation Exchange Capacity, Cation Saturation Ratios, and Sulfur Across a Wide Range of Soils

“…The 0.01 M SrCl 2 extraction method with 5-min shaking time and 1:10 soil-to-solution ratio resulted in extractable S data that were directly comparable to those obtained with the 0.01 M CaCl 2 extraction method with 30-min shaking time and 1:5 soil-to-solution ratio reported in Ketterings et al (2011a): CaCl 2 extractable S (mg kg −1 ) = 0.97*SrCl 2 extractable S (mg kg −1 ), R 2 = 0.9976, and RMSE = 0.28 mg kg −1 (Fig. 3).…”

“…Briefly, 10 g of soil was shaken in 50 mL of 0.01 M CaCl 2 (1:5 soil-to-solution ratio; wt:vol) for 30 min as described in Ketterings et al (2011a). Briefly, 10 g of soil was shaken in 50 mL of 0.01 M CaCl 2 (1:5 soil-to-solution ratio; wt:vol) for 30 min as described in Ketterings et al (2011a).…”

“…In recent years, a comparison of soil test S methods resulted in the release of a new soil S test for detecting S deficiencies in alfalfa in New York (Ketterings et al, 2011a). This method uses a 30-min 0.01 M CaCl 2 extraction procedure with a 1:5 soil-to-solution ratio.…”

Sulphur status in agricultural soils determined using the Mehlich 3 method

“…Although Mehlich 3 extractant was not always reported to be the best choice in comparison with the other extractants (Matula 1999, Esmel 2010, Ketterings et al 2011) the results of our study clearly proved that Mehlich 3 extractant can be a valuable source of information about the S status in agricultural soils. But for a reliable fertilizer recommendation it is necessary to have also some information about subsoil S, local aerial deposition and possible access of plant roots to rich S groundwater or capillary ascending water (Haneklaus et al 2002), as well as the data about relationships between Mehlich 3 results and S content in plants and its uptake.…”

Soil and Tissue Testing for Sulfur Management of Alfalfa in New York State

“…The general conclusion is that no one procedure has proved consistently superior in predicting responses to S fertilization (Johnson and Fixen, 1990). In a recent study, Ketterings et al (2011) compared six S soil‐testing methods for their ability to detect S fertilizer addition using four New York soils. The 0.01 mol L −1 CaCl 2 extraction (Williams and Steinberg, 1959) with inductively coupled plasma atomic emission spectroscopy (ICP–AES) detection of S in solution was best correlated with the S added, and the regression equation had the largest slope and showed the greatest consistency between ICP–AES and turbidimetric determination of S in solution (Ketterings et al, 2011).…”