Influence of leguminous cover crops on microbial and selected enzyme activities in soils of a plantation

A study dealing with ecological sustainability of plantation based land use initiated in 1991 and in a 19 yr old coconut plantation consists of growin g certain leguminous crops like Atylosia, Pueraria, Centrosema and Calopogo nium as soil cover in separate plots with lemon grass as live bounds. These cover crops are grown during the rainy season and incorporated into the so il towards the end of the monsoon every year. The effect of such cover crop s on soil microbial counts (total counts, fungi, actinomycetes and bacteria ), biomass C, organic C, total N and on the activity of enzymes like urease , amidase, L-glutaminase, aryl sulphatase and dehydrogenase was determined in soils (Ap horizon) collected from these plots after 5 years. Soils with cover crops registered significantly higher microbial biomass, b iomass C, organic C and total N compared to control. Consequently, all the enzymes were activated to different degrees in soils with cove crops. Signi ficant and positive relationships of enzyme activities with organic C, mine ral N and total N suggested that growing cover crops, increased C turnover and N availability and therefore, provided a conducive environment for micr obial proliferation, enzyme synthesis and accumulation in the soil matrix.