Dahanayake, P.M.Premetilake, M.M.S.N.Henegamage, A.P.Herath, H.M.S.K.2019-04-062019-04-062019-029789550481255http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/93/53.pdf?sequence=1&isAllowed=yNutrient cycling is essential for the stability of an ecosystem where soil microorganisms play a significant role. Some allelochemicals such as α-pinene produced by certain plant species may suppress the activity of these microorganisms. Eucalyptus, which is a popular plantation species in Sri Lanka, is known to emit α-pinene. However, its effect on soil microorganisms and soil fertility is not well known. The present study investigated the relationship between α-pinene content, soil microorganisms and soil organic carbon content in 7-year-old Eucalyptus grandis and Eucalyptus torelliana plantations. As the control plantation, an adjacent Patna grassland (previous land-use before afforestation) was used. Three subplots (20 × 20 m) were established within each site and soil was sampled up to 15 cm depth. Soil organic carbon content was measured according to the Walkley-Black method. Following a serial dilution, bacteria and fungi were cultured and CFU mL-1 was calculated. The α-pinene in soil samples was extracted using petroleum ether and was analyzed using GC-MS. According to the results, there was a significant (P<0.05) variation between organic carbon, α-pinene content and bacteria quantity between the plantations and the adjacent grasslands. However, there was no significant (P>0.05) variation in fungi quantity. The highest organic carbon content was observed in E. torelliana plantation (2.08% ±0.3), however; the highest α-pinene content was found under E. grandis plantation (0.14% ± 0.09). Interestingly, the highest bacterial count was recorded under E. grandis plantation (3.0 x 105 CFU mL-1) while the highest fungi count was recorded in grassland. There were no significant (P>0.05) correlations between the soil α-pinene content, soil bacterial and fungal count fungal and the organic carbon. There is no significant effect (P>0.05) of α-pinene content on the bacterial and fungal counts and organic carbon in young E. grandis and E. torelliana plantations.enBioprocess TechnologyBiotechnologyBio Chemicals EngineeringOther