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

Abstract

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.

Potassium‐fertilizer management in winter oilseed‐rape production in China

“…Both the M3 and ASI extraction methods, which are similar to the NH 4 OAc method, have been more readily accepted in recent years as a measure of available soil K because they are convenient in permitting the extraction of other mineral nutrients in one procedure and improve laboratory efficiency. Many studies have shown that available soil K as determined using the ASI and M3 methods is significantly positively correlated to that using the NH 4 OAc method (Loide et al, 2005;Xiong et al, 2007;Slaton et al, 2010). Positive correlations between soil NH 4 OAc-K and ASI-K and M3-K were also observed in our studies (data not shown).…”

On-farm trials of optimal fertilizer recommendations for the maintenance of high seed yields in winter oilseed rape (Brassica napus L.) production

“…The positive correlation between soil NH 4 OAc-K contents and the yield response to K fertilizer have been mentioned in many studies (Mallarino et al 2003;Loide et al 2005;Slaton et al 2010). But the relationship between soil NH 4 OAc-K content and relative yield was weak in our study because of minor response to K fertilization.…”

Potassium Fertility Effects Yield Components and Seed Potassium Concentration of Determinate and Indeterminate Soybean

“…Soybean seed yield can be decreased by more than 50% by K deficiency (Nelson et al, 1946; Jones et al, 1977), but losses of 5 to 20% are more common (Coale and Grove, 1990; Mallarino et al, 1991; Slaton et al, 2010; Clover and Mallarino, 2013). Crop yield loss associated with the physiological effects of K deficiency is partially attributed to reduced assimilate production (Ashley and Goodson, 1972; Sale and Campbell, 1986) and partitioning to the seeds (Ashley and Goodson, 1972; Huber, 1984) due to the reduction in enzymatic activity (Huber, 1984).…”