IPI International Potash Institute
IPI International Potash Institute

Scientific abstracts

Correlation of Field-Moist, Oven-Dry, and Air-Dry Soil Potassium for Mid-Atlantic USA Soybean
Williams, A.S., Md. R. Parvej, D.L. Holshouser, W.H. Frame, and M.S. Reiter
Published in:
Soil Sci. Soc. Am. J. 81(6):1586-1594 (2018), English


The extractable soil-K concentration, used for fertilizer-K recommendations, may be affected by soil drying. Although air or oven drying are the most common soil processing me, K from field-moist soil has been documented to be a better predictor of soil-K availabilities and fertilizer-K needs for soybean [Glycine max. (L.) Merr.] grown on fertile silt loam to clayey soils. We evaluated the effect of four soil processing methods (field-moist [FM], air-dry [AD], air-dry followed by oven-dry [ADOD], and oven-dry [OD]) in predicting extractable soil-K availability for soybean production on less fertile Mid-Atlantic sandy-textured soils. Twelve soybean field trials were conducted in 2014 on Coastal Plain and Piedmont soils in Virginia and North Carolina. Soil K was extracted by Mehlich-1 with each soil processing method and correlated with soybean relative yield. Soil-K concentrations from each method were statistically similar and strongly correlated (r2 = 0.94-0.98) with each other having intercept and slope coefficients that were not different from zero and one, respectively. Extractable soil-K concentrations from each method were also strongly correlated with soybean relative yield and explained 93 to 95% of the relative yield variation for FM soil, 95 to 96% for AD soil, 83 to 86% for ADOD soil, and 94 to 95% for OD soil. Results suggest that soil-K concentrations from FM, AD, and OD samples are similar in predicting K availability for soybean. Soil drying should not be an issue of concern in extracting soil K and recommending fertilizer-K rate for soybean production on Mid-Atlantic coarse-textured Coastal Plain and Piedmont soils.

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