Influence of inorganic and organic nutrient sources on soil enzyme activities

Abstract

Pot experiments during rabi 2004-05 and 2005-06 in lysimeter and an incubation study in laboratory were conducted with 12 treatments comprising of recommended doses of fertilizers (RDF) i.e. NPK (120, 60 and 60 kg ha-1), RDF +10 kg N through 5 organic sources viz., farmyard manure (FYM), carpet waste (CW), pressmud (PM), digested sludge (DS) and poultry manure (PyM), and alone treatments of above organic wastes equivalent to 120 N ha-1 on wheat cv. HUW-533 in lysimeter at Banaras Hindu University (BHU), Varanasi. The content of nitrogen in above organics was 0.5, 12, 1.0, 1.0 and 2.5%, respectively. All the integrated treatments of RDF +10 kg N ha-1 through each of the above five organic sources showed greater urease activity than the other treatments at different days after incubation (DAI) whereas the activity of dehydrogenase (DHA) and alkaline phosphatase were more with absolute treatments of the above organic sources of nutrients. In case of incubation study, highest and significant urease (300 μg urea hydrolyzed g-1 h-1) activity was recorded at 30 DAI in the treatment receiving full doses of RDF + 85 kg CW ha-1 followed by treatments of RDF + 2 t FYM and RDF + 1 t PM significantly superior over absolute control (T1). Similarly, maximum build-up of dehydrogenase (74.5 μg TPF g-1day-1) and alkaline phosphatase (90.7 μg pNP produced g-1 h-1) was found in the soils treated with FYM (T8) and with press-mud (T10) at 30 DAI and 120 DAI, respectively.