Effect of different organic manures on enzyme activities in a flooded rice soil

摘要

A pot culture experiment was conducted to study the effect of organic manures viz., Sesbania aculeata, Sesbania speciosa, Crotolaria juncea, Azolla microphylla, cowpea, farmyard manure, coir pith compost and paddy straw applied at 100 kg N ha~(-1) onurease, dehydrogenase and phosphatase activities in the soil, with rice variety IR 60 as the test crop, Sesbania aculeata registered the maximum urease and dehydrogenase activities and Sesbania speciosa the maximum phosphatase activity. In general, greenmanures recorded higher enzyme activities than farmyard manure, coir pith compost and paddy straw. Activities of urease and dehydrogenase increased upto 20 days after transplanting (DAT) and phosphatase activity upto 40 DAT and declined thereafter, Therice rhizosphere recorded higher enzyme activities than the non-rhizosphere soil. The enzyme activities were positively correlated with organic carbon content.