SOLUTION, EXCHANGEABLE, AND NONEXCHANGEABLE POTASSIUM IN FIVE SOIL SERIES FROM THE ALLUVIAL SOILS REGION OF NORTHERN INDIA

Abstract

We investigated soils belonging to five soil series from the alluvial belt of northern India. These series differed in their solution, exchangeable, and nonexchange- able potassium (K). Potassium desorbed by electroultrafiltration (EUF) in 10 min (EUF-10) was almost equal to water-soluble K (1:5 soil water extract). Potassium desorbed by EUF in 35 min (EUF-35) was less than ammonium-acetate-extractable K (NH4OAc), which was much less than boiling nitric-acid-soluble K (reserve). Water-soluble K was 17 to 30% of NH4OAc K, which, in turn, was 6 to 16% of reserve K. Soils with high amounts of exchangeable K and percentage of K saturation recorded higher amounts of K in solution. At constant exchangeable K, the water-soluble K in the Nabha series was almost double that of the Khatki and Rarha series. The Khatki and Rarha series with comparatively heavier texture had high reserve K, although the rate of release of K was low. The Nabha series with comparatively less reserve K had the highest rate of K release. The Lukhi series, low in both NHjOAc and reserve K, had an intermediate rate of K release. The Nabha soils, with the maximum rate of K release, are expected to deplete much faster than the Khatki and Rarha series that have high reserves of K, but slow rates of release. © Williams & Wilkins 1986. All Rights Reserved.