Determination of Soil Microbial Population and Enzyme Activities under Jasmine Cultivation as Influenced by Nutrient Sources

Multi nutrient deficiencies in soil have been reported with increasing frequency over the past two decades on a worldwide scale, is considered as an important factor that reduces yield and affects the quality of harvested products. Nutrient cycling and transformation of in soil is influenced by microbes and the availability of organic and inorganic nutrients to plants and microbes can both be controlled through enzyme activities. Keeping this in view a field experiment was conducted at O. Alangulam village of Thiruparankundram block, Madurai district, Tamil Nadu during 2016-18. The objectives of the study were to evaluate the influence of Sulphur at different levels of pressmud and gypsum with or without the recommended inorganic fertilisers through various sources such as single super phosphate(SSP) and Suphala on soil microbial population and enzyme activities and optimize the sulphur requirement of Jasmine (Jasminum sambac). The significantly higher bacterial population of 124 × 106 CFU g-1 was observed in the treatment that received pressmud as sulphur source @ 60 g sulphur/plant/year along with RDF (recommended dose of fertilisers were applied @ 60:120:120 g of N:P2O5:K2O/plant/ year in the form of urea, SSP and MOP).This was followed by the treatment that received pressmud @ 40 g sulphur/plant/year along with RDF (111 × 106 CFU g-1). Application of inorganic NPK fertilizers without organics decreased the activities of dehydrogenase and aryl sulphatase enzymes. The flower yield hectare-1 ranged from 3.8 to 15.4 tonnes ha-1as influenced by various nutrient sources. Application of RDF along with Gypsum @ 60 g sulphur/ plant/year recorded significantly higher yield followed by the treatment that received RDF along with Pressmud @ 60 g sulphur/plant/year.