Evaluation of suitable extractant for estimating soil available potassium in soils of Tamil Nadu

Abstract

The assessment of soil available potassium (K) using a suitable extractant under various soil types is essential for making sound fertilizer recommendations. In the present study, suitability of six chemical extractants was evaluated using 50 georeferenced soils of Tamil Nadu for prediction of plant available K in maize (var CO-6) grown in Neubauer technique. Mean of soil K by different extractants were in the following order: Kelowna II (136.58 mg kg-1) > Ammonium Acetate (121.86 mg kg-1) > AB-DTPA (107.46 mg kg-1) > Mehlich 3 (91.23 mg kg-1) > 0.01 M CaCl2 (40.85 mg kg-1) > Distilled water (20.33 mg kg-1). The highest simple correlation with plant K uptake was obtained with Kelowna II (r = 0.74**) and lowest with 0.01M CaCl2 (r = 0.62**). Based on the R2 value, the Kelowna II extractant was found to be the most suitable one followed by 1 N NH4OAc irrespective of soil variables.