Comparison of some extractants for extracting available potassium for rice in some soils of Kohgiluyeh Province

Potassium and nitrogen are two major nutrients, have important role in increasing rice quantity and quality. Potassium like nitrogen is taken up in large amount by rice. Evaluation of nutrient status in soil is important from nutritional, environmental and economical aspects. This study was conducted in order to evaluate 11 different chemical extractants for determining suitable extractants for estimation of available potassium of rice in 11 selected soils of Kohgiluyeh Province. Rice seeds were cultivated in 1.5 kg pots in three replications and harvested after 10 weeks. Plant potassium was extracted with 1N HCl. Soil available potassium was extracted using 1M NH4OAC, 1 and 2M sodium chloride, 0.025 M sulfuric acid, 0.1M barium chloride, 0.01M calcium chloride, Morgan-Wolf, AB-DTPA, 1N NaOAC, 1M magnesium acetate and 2M Hydrochloric acid. The amount of K extracted by 1N NaOAC and 1N NH4OAC, was significantly (r=0.85** and 0.73**, respectively) correlated with K concentration, followed by Morgan and 2N NaCl. The lowest correlation is belonged to 1N HCl. Therefore, due to the simplicity and economy, the rate of extraction and the high correlation, extractants of 1N NaOAC and 1N NH4OAC are recommended as suitable extractants for determining the available K uptake by rice in the soil studied.