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Evaluating plant available potassium with strontium citrate

1994; Taylor & Francis; Volume: 25; Issue: 9-10 Linguagem: Inglês

10.1080/00103629409369152

1532-2416

R. R. Simard, Ján Žižka,

Soil and Unsaturated Flow

Abstract The 0.02M strontium chloride (SrCl2) and 0.05M citric acid solution (Sr‐citrate) was developed for the simultaneous determination of availability indices for plant nutrients from soils. The objective of this study was to compare the Sr‐citrate extracting solution with water, 0.002M SrCl2, 0.1M barium chloride (BaCl2), 0.1M hydrochloric acid (HCl), 1M ammonium acetate (NH4OAc), and Mehlich 3 soil extractants as predictors of plant‐available potassium (K) for alfalfa (Medicago sativa L.) in the greenhouse. The Sr‐citrate solution extracted more soil K than SrCl2 and BaCl2 but less than the other extractants. The Sr‐citrate solution was best for predicting K uptake from low cation exchange capacity (CEC < 15 cmolc/kg) soils and adequately predicted plant uptake from higher CEC soils and the relative yield of alfalfa in all soils. The relationship between Sr‐citrate K and plant uptake was slightly improved when boiling nitric acid (HNO3)‐extracted K or organic matter content was included in the multiple regression equation. The results of this study show that the Sr‐citrate procedure can adequately predict the amount of plant‐available K in soils.