POTASSIUM STATUS IN MAIZE RHIZOSPHERE OF SMECTITIC SOILS

This study has been taken up to generate information on potassium stat us in maize rhizosphere soils differing in their clay content at diffe rent levels of added potassium. Soils with larger amounts of clay show ed greater amounts of water soluble and ammonium acetate extractable K (NH4OAc K) in both the rhizosphere as wells as non-rhizosphere. In th e absence of added K (control), non-rhizosphere samples showed higher water soluble and NH4OAc K ranging from 8.0 to 28.9 mg kg(-1) and from 132.5 to 294.0 mg kg(-1), respectively compared to rhizosphere sample s where water soluble K varied between 6.0 and 26.5 mg kg(-1) and NH4O Ac K from 125.0 to 262.5 mg kg(-1). The difference in K content betwee n rhizosphere and non-rhizosphere which could have been resulted from plant K uptake was significantly related with clay content (r = 0.98* ) in control whereas at 150 mg kg(-1) K addition this relationship was found to be non significant (r = 0.64(NS)). Electro ultra filtration (EUF) fractions also showed similar differences in K contents in soil between rhizosphere and non-rhizosphere.