Comparative Assessment of Extractants for Available Potassium in Calcareous Soil of Punjab

The overestimation of potassium (K) levels in ammonium acetate extractant has led to a significant concern in calcareous soil (CS). Therefore, a pot experiment was conducted to investigate the response of K application on grain yield and to determine the most suitable extractant along with their critical limits. The study utilized soil collected from both calcareous and non-calcareous soils, which were subjected to ten levels of K in a completely randomized design with three replications. The findings revealed that K application had a positive effect on yield and yield parameters in calcareous soils, up to 13.5%, with a response up to 7.5 mg kg−1. The study also demonstrated that grain and straw K concentrations were 2.5% and 8.9% higher, respectively, in calcareous soils when compared to non-calcareous soils (NCS). The study also tested the effectiveness of different extractants in extracting K from both soils. The available K extracted using various extractants varied, with the highest correlation coefficient (r = 0.87***) found in the barium chloride (BaCl2) extractant. The critical limit of soil-K by Cate-Nelson method was found to be 964.3 kg ha−1 for 0.1 M BaCl2, 0.74% for grain, and 3.55% in straw in CS. In conclusion, K application had a significant effect on yield and yield parameters in calcareous soils, with barium chloride being the most effective extractant for estimating potassium levels. The findings of this study provide valuable insights into the appropriate extractants and critical limits for the accurate evaluation of K levels in calcareous soils.