Assessment of microbial biomass and enzyme activities in soil under temperate fruit crops in north western himalayan region

Microbial communities are important for the functioning of the ecosystem, both in relation to direct interactions with the plants and with regard to nutrient and organic matter recycling. A study in field condition was undertaken in Kashmir valley to reveal the effect of various temperate fruit crops viz. apricot, peach, plum and cherry along with a control (no-plantation) on microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP) and dehydrogenase, phosphomonoesterase (acid and alkaline) and urease activities in soil at two different depths (0-20 and 21-40 cm). All the fruit crops showed a sharp decline in microbial biomass and enzyme activities with the increase in soil depth. Each of the four fruit crops showed significant (p<0.05) impact on MBC over the control and the maximum MBC was recorded in plum (1000 mg kg -1 ) and the lowest value was observed in control (457 mg kg -1 ), at the surface layer. Since there is a relationship between MBC and MBN, the similar trend was also observed in MBN as in case of MBC. For MBP, fruit crops showed any significant effect neither on surface soil, nor on subsurface soil layer over control. At the surface layer, unlike microbial biomass the highest dehydrogenase activity was observed in peach (318 g TPF g soil -1 h -1 ) and the lowest value (166 g TPF g soil -1 h -1 ) was attained at control plot. Maximum alkaline phosphomonoesterase activity was observed in peach (381 g PNP g soil -1 h -1 ), although for acid phosphomonoesterase the highest value recorded in apricot (306 g PNP g soil -1 hr -1 ), at surface soil. A significant positive correlation (p <0.01) was observed amongst MBC, MBN and MBP. Both the phosphomonoesterase activities were significantly (p <0.05) correlated with MBP in soil. It can be concluded that the influence of the studied fruit crops on the soil was not uniform, in terms of the measured parameters.