Potassium deficiency in agricultural soils is a largely unrecognized but potentially significant threat to global food security if left unaddressed, finds new research involving researchers at UCL, University of Edinburgh and the UK Center for Ecology & Hydrology.
I do, and read the source paper linked by another commenter as well. The paper itself refers to ‘plant available K’, which is exchangeable K. That’s the potassium dissolved in the water in the soil at the time of the sample being taken, and is not indicative of the total amount of potassium held in the soil. Chasing results from a bad test is a surefire way to get bad results, like starting life saving measures because someone only took a pulse for the split second in between someone’s heartbeats.
The soils in the deficient regions are not just deficient in bioavailable but also in the forms that would need to be liberated for plant use throughout the growing season. just look at the chemistry of a Brazillian or sub-Saharan Oxisol.