Evaluation of some soil test methods in acid soils for available phosphorus for soybean of Imphal East District, Manipur (India)

Abstract

Evaluation of nutrient status in soil is important for nutritional, environmental and economical aspects. Phosphorus is a very important nutrient for leguminous crops. In order to evaluate the phosphorus availability, six soil test methods were carried out for predicting response of soybean to phosphorus application on twenty surface soils (0-15 cm) of Imphal East District, Manipur were studied. The suitability of these extractants was in the descending order: Bray P 1 > Mehlich P 1 > Bray P 2 > Troug P > Olsen P > Morgan P. Bray's P 1 extractable phosphorus showed the highest and positive correlations with phosphorus content (control), phosphorus uptake (control), Bray's percent yield and uptake. Therefore, this extractant may be used as an index of available phosphorus for soybean (JS-335) grown on acid soils of Imphal East District, Manipur, the critical level being 13 ppm (mg kg-1). The critical limit of phosphorus concentration in plant at 40 days of planting was 0.22%.