An Improved Woodruff Buffer for Estimation of Lime Requirements

Abstract

The dominant quick‐test method of estimating soil lime requirements in the USA Corn Belt and adjacent area is the Shoemaker, McLean, Pratt (SMP) buffer method. This work was done to compare an improved Woodruff buffer with the SMP buffer to determine which most accurately estimated soil lime requirement. This study used a Ca(OH)2‐CaCl2 soil titration procedure and incubation of soils with finely ground, chemically pure CaCO3 to compare the accuracy of the original Woodruff procedure, the SMP single buffer procedure, and the new Woodruff procedure in estimating the lime requirements of 89 soil samples. The results supported 1961 findings by Ohio workers that the original Woodruff procedure drastically underestimated lime requirements. The results also supported the literature that the SMP procedure underestimates low lime requirements. The SMP tended to overestimate high lime requirements. Based upon the results of this study, the new Woodruff procedure was a better predictor of lime requirements than the SMP procedure.

Delineation of Management Zones for Site-Specific Information about Soil Fertility Characteristics through Proximal Sensing of Potato Fields

“…Phosphorus was measured using Olsen method [34], K using Flame photometric method [35], Fe with colorimetric method [36], CEC with BaCl 2 -compulsive exchange procedure [37], and pH was determined using a pH multimeter. The LI was determined by mixing the SMP buffer solution with soil and followed by measuring its pH [38]. Soil organic matter was determined using standard methods [39,40].…”

Evaluating buffer methods for determining lime requirement on acidified agricultural soils of the Palouse

“…The calibration recommended for the WR ranged from an overestimate of 0.37 Mg ha −1 on the Larkin soil to an underestimate of 2.82 Mg ha −1 on the Joel soil (Table 5). The SMP buffer method was developed on Ohio soils in response to the suggested inadequacy of the Woodruff buffer's ability to compensate for soil acidity contributed by Al (Brown & Cisco, 1984; Shoemaker et al., 1961). Acidity contributed by H + was the only form of acidity considered in the development of the original Woodruff method (Woodruff, 1948).…”

“…The Woodruff 6 method, using the existing calibration, was more effective at estimating lower lime rates compared with higher rates (Table 5). Underestimating recommendations when higher levels of lime are required could be attributed to a trend noted in previous evaluations of the Woodruff method, where the original method was indicated to be less effective at capturing exchangeable Al acidity (Brown & Cisco, 1984). The initial pH of the Woodruff 6 buffer solution is 6.0.…”

Double-Buffer Methods Revisited with Focus on Ionic Strength and Soil/Solution Ratio

“…uff er solutions are commonly used in soil testing for a quick assessment of soil acidity and the lime required to neutralize the soil acidity. A soil-buff er pH is the pH of a soil and buff er mixture commonly determined aft er a soil-water pH (1:1 soil/water) (Soil and Plant Analysis Council, 2000) or a soil-salt pH (1:1 soil/0.01 mol L −1 CaCl 2 ) (Brown and Cisco, 1984). Th e lower the soilbuff er pH is from the original pH of the buff er solution, the greater the amount of soil acidity and the greater the lime requirement (LR).…”