Potassium availability and soil extraction tests in agricultural soils with low exchangeable potassium content

• DOI: 10.17221/8190-pse
• Publication Date: 2015-05-20T14:45:11Z
• Authors: M. Madaras; M. Koubová
• Keywords: Soil test; Potash; Cation-exchange capacity

Low application of fertilizer potassium (K) in intensive agriculture leads to a gradual decrease and, afterwards, steady state soil K determined by tests which are based on exchangeable (Kexch) extraction. In this situation, non-exchangeable (Knon-exch) is being released and therefore real plant availability does not necessarily correspond test K. This incoherency was investigated 14 agricultural soils with low as the Mehlich 3 method. Plant-available exhaustive cropping perennial ryegrass Neubauer seedling were compared 8 extraction methods, total content relative K-bearing minerals. (314 mg/kg average) more than 3-times higher Kexch but from 2 times lower Knon-exch extracting methods. The mixed-layer phyllosilicates significantly related extracted tests. orthoclase correlated only mica-group minerals none extractions. best prediction plant-available obtained sodium tetraphenylboron StepK