Extractable Potassium as Affected by Soil Moisture Conditions

Soil moisture and probe characteristics affect core integrity and soil test results

“…In general, drying soil samples tends to increase soil K extraction on soils with low soil K concentrations and decrease the amount of K extracted from soils with high K concentrations (Grava et al., 1961; Luebs et al., 1956; Martins et al., 2015; Rechcigl et al., 1992), which might be associated with the release of K from 2:1 minerals with drying. Scott and Smith (1968) concluded that K is released when clay layers crack and separate on drying, a similar trend was also reported by Barbagelata and Mallarino (2012) when comparing oven‐dry and field‐moist soil K. Overall, the literature suggests soil drying and moisture status at the time of sampling have a less pronounced effect on P, S, and Zn as compared to K. Ferrando and Barbazán (2022) showed that higher moisture increased K availability in soils from Uruguay but reported that short‐term flooding did not affect soil test K. Research has documented that soil moisture affects nutrient solubility and extractability, but, for K, the effect tends to vary according to soil intrinsic properties and complex and largely unpredictable reactions between several soil nutrient pools.…”