CUMULATIVE AND RESIDUAL EFFECTS OF INM OF KHARIF RICE ON SOIL ENZYME ACTIVITIES IN RABI GREENGRAM (Vigna radiata)

The cumulative and residual effects of integrated nutrient management of kharif rice on soil enzyme activities i.e urease, phosphatase, dehydrogenase and cellulase at different growth stages of rabi greengram were tested in an Inceptisol in North Coastal Zone of Andhra Pradesh during rabi 2009 and 2010. Results revealed that all the cumulative treatments showed higher soil enzyme activities at different stages of greengram than their corresponding residual treatments in both the years. Urease, phosphatase, dehydrogenase and cellulase activities at different growth stages of the greengram gradually increased over the age of the crop and attained higher activity at flowering and gradually decreased at harvest. All the enzyme activities except cellulase were significantly higher in the plots which received 75 % RDFN + vegetable market waste vermicompost @ 2.5 t ha-1, during preceding rice crop. It was closely followed by 75 % RDFN + weed vermicompost @ 2.5 t ha-1 and 100 % Prathista organic manures. Whereas higher cellulase activity was recorded in paddy straw vermicompost treated plots. The over all effect of chemical fertilizers was found to be lower than integrated use of different vermicomposts with respect to enzyme activity during both the years.