Correlation and Calibration of Soil Potassium Availability with Soybean Yield and Trifoliolate Potassium

• Published in: Soil Science Society of America journal Vol. 74; no. 5; pp. 1642 - 1651
• Main Authors: Slaton, Nathan A, Golden, Bobby R, DeLong, Russell E, Mozaffari, Morteza
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.09.2010; Soil Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Availability; Biological and medical sciences; Calibration; Correlation; Crop rotation; Crop yield; Cultivars; developmental stages; Earth sciences; Earth, ocean, space; Exact sciences and technology; fertilizer rates; field crops; Fundamental and applied biological sciences. Psychology; Glycine max; Irrigation; Leaves; Loam soils; Loams; Mathematical models; Methods; nutrient availability; Nutrient deficiency; nutritional status; Pest control; plant nutrition; Potassium; potassium fertilizers; Silt loam; Silts; Soil (material); soil fertility; Soil nutrients; Soil science; Soil testing; Soils; Soybeans; Surficial geology; Arkansas; Vegetals; potassium; alkali metals; Available nutrient; Earth science; Inorganic element; Glycine max; Grain legume; Leguminosae; correlation; Dicotyledones; Angiospermae; Spermatophyta; Yield; Soil science; soils; C3-Type; calibration; Oil plant (vegetal)
• ISSN: 0361-5995; 1435-0661; 1435-0661
• DOI: 10.2136/sssaj2009.0197

The ability of soil tests to identify nutrient-deficient soils and recommend fertilizer rates that optimize agronomic yield is essential for profitable soybean [Glycine max (L.) Merr.] production. Our objectives were to correlate relative soybean yield to Mehlich-3 and 1 mol L−1 HNO3–extractable soil K and trifoliolate-leaf K concentration at the R1 to R2 development stage and calibrate the K rates for Mehlich-3-extractable soil K. Experiments were established on silt loams at 34 site-years planted with a Maturity Group IV or V cultivar and fertilized at five K rates (0–148 kg K ha−1). Mehlich-3-extractable soil K ranged from 46 to 167 mg K kg−1 and produced relative soybean yields of 59 to 100% when no K was applied. Eleven sites had Mehlich-3-extractable K < 91 mg K kg−1 and all responded positively to K fertilization. Soybean grown in soil having 91 to 130 mg K kg−1 responded positively at nine of 15 sites. Mehlich-3 soil K explained 76 to 79% of the variability in relative yields and had critical concentrations of 108 to 114 mg K kg−1, depending on the model. The linear-plateau model predicted the critical HNO3–extractable soil K to be 480 mg K kg−1. Trifoliolate-leaf K concentration increased significantly, positively, and linearly as Mehlich-3- and HNO3–extractable soil K increased, but Mehlich-3 soil K explained only 49 to 53% of the variation in trifoliolate-leaf K. Mehlich-3-extractable K is an excellent predictor of soil K availability for soybean grown on silt loams in eastern Arkansas.