Abstract

Selected rhizosphere soil chemical properties were studied to establish changes in soil fertility status in response to Rhizobium inoculation in Phaseolus vulgaris L., molybdenum and lime supply after the growing season. The experiment was laid in a split-split plot and consisted of 2 levels of Rhizobium inoculation (with and without rhizobia), 3 levels of Mo (0, 6 and 12 g kg^-1 of seeds) and 3 levels of lime (0, 2 and 3 t ha^-1). Rhizobium inoculation showed significant increase in the soil pH, Ca and Na. The available micronutrients Fe, Cu, Zn and Mn were also significantly increased in the Rhizobium inoculated treatments compared with the uninoculated controls. Molybdenum and lime supplied individually significantly increased the soil pH. Furthermore, Ca and Mg levels in the soil were significantly increased with lime. Interactive effects were found between Rhizobium and Mo on pH changes in the rhizosphere. Rhizobium inoculation, liming and Mo application are the strategies used to appropriately supply nutrients to the plants. In this study, inoculation significantly increased the soil pH and the availability of Ca, Na, Fe, Cu, Zn and Mn in the rhizosphere. The increased available nutrients due Rhizobiuminoculation could be due to increased soil pH condition to near neutral values. Additions of lime resulted in increased soil pH and exchangeable Ca and Mg.Repeated applications of these inputs in the study area is recommended because soils are acidic in nature.

Key words: Calcium, copper, iron, magnesium, manganese, potassium, phosphorous, sodium, soil pH, zinc.