Effect of Different Kharif Paddy Straw Management Options and Different Levels of Nitrogen on Soil Dehydrogenase and Urease Activity

A field experiment was conducted during rabi 2020-21, at Regional Agricultural Research Station, Polasa, Jagtial, PJTSAU to study soil dehydrogenase and urease activity as influenced by different kharif paddy straw management options and nitrogen levels. The results reveal that dehydrogenase and urease activity of soil was significantly influenced by paddy straw management options and activity was increased with crop duration up to 60 DAT and decreased after harvest. Dehydrogenase activity was reduced after burning (1.93 mg TPF produced g-1 soil d-1) as compared to the initial values (2.34 mg TPF produced g-1 soil d-1). The highest dehydrogenase activity of 3.74 and 3.54 mg TPF produced g-1 soil d-1 was recorded at 60 DAT in paddy straw incorporation with phosphorus and incorporation without phosphorus and decreased to 3.36 and 3.03 mg TPF produced g-1 soil d-1 after harvest respectively. Soil urease activity was showed an increasing trend with crop duration up to 60 DAT and then declined. Maximum activity of 3.05, 4.84, 5.17 mg NH4+ released g-1 soil h-1 was observed at 60 DAT under paddy straw burning, paddy straw incorporation with phosphorus incorporation without phosphorus respectively. Paddy straw incorporation with phosphorus recorded higher urease activity and paddy straw burning recorded lower urease activity at all the intervals of crop growth. The effect of nitrogen levels on soil urease activity was found to be significant. Soil urease was highest with 120% RDN followed by 115% RDN, followed by 110% RDN, followed by 100% RDN and the similar trend was observed at all the intervals of crop growth.