Nutrient Availability and Biochemical Properties in Soil as Influenced by Organic Farming of Papaya under Coorg Region of Karnataka

In the recent years, papaya cultivation in India has become more popular because of its high yield and nutritive qualities. There also have emerged niche markets for organically produced fruits especially in the urban areas. Keeping in view the emerging trend, a study was conducted at Central Horticultural Experiment Station (IIHR) during 2004-07 in order to organize modules for sustainable production of organic papaya var. 'Coorg Honey Dew' under Coorg region of Karnataka, India. In this study, the effects of seven different treatments viz., recommended dose of NPK fertilizers (250: 250: 500 g NPK plant(-1) year(-1) as check (T-1); FYM 20 kg/plant (T-2), urban compost 13.5 kg/plant (T-3), sun hemp 25 kg/plant (T-4), sun hemp 40 kg/plant + rock phosphate 300 g/plant (T-5), neem cake 4 kg + wood ash 2.5 kg/plant (T-6) and rural compost 35 kg/plant (T-7) applied to 'Coorg Honey Dew' papaya crop were studied on nutrient availability, microbial population and enzyme activities in sandy loam soil in a field experiment laid out in randomized block design with three replications. Soil analysis after three years of study indicated no significant effect of treatments on the status of available P and K and the pH of the soil. Organic matter content in soil was significantly influenced by different treatments with the highest values recorded under T-2 and T-3 treatments. Soils under different organic modules had significantly higher microbial population (bacteria, fungi and actinomycetes) and activities of urease, phosphatase, dehydrogenase and cellulases as compared to that under recommended dose of fertilizers (T-1). Significant positive association between organic matter status, microbial populations and enzyme activities in soil was recorded. Application of FYM 20 kg/plant (T-2) was the best organic module with regard to higher microbial populations and enzyme activities in soil.