Jorhat's Tea Soil Microbes Grow Best at 18 to 30°C

Sampling between 2016 and 2019 on five Jorhat tea estates has put a figure on the soil's microbes: its bacteria and fungi grew best between 18 and 30 degrees Celsius (about 64 to 86 degrees Fahrenheit), according to a study Nagaland University announced in late July.

The study was published June 3 in the journal Environments. The more bacteria and fungi a soil held, the more active its enzymes were, a link the authors read as the microbes' role in sustaining vital soil processes. By their microbes and enzymes the five estates fell into two groups, and each group kept its pattern across the seasons.

A separate study by Tocklai and UPASI scientists, published in June, found daytime highs on Assam's South Bank and at Nagrakata in West Bengal running 1.1 to 1.3°C (about 2°F) above their long-term averages. Neither paper says how often Jorhat now runs outside the 18 to 30 degree band.

The paper's 14 authors are led by Bobita Payeng of the Tea Research Association's Upper Assam Advisory Centre and include two scientists from the soils department at the Tocklai Tea Research Institute in Jorhat. Tanmoy Karak of Nagaland University's Department of Soil Science, the last-listed author, said the team set out "to determine seasonal thresholds that favour beneficial microbial communities."

Sources: Payeng et al., "Seasonal and Climatic Influences on Soil Microbial Communities and Their Enzymatic Activities in Five Tea Plantations in Jorhat, Assam, India", Environments 13(6):314, June 3, 2026; Team EastMojo, "Nagaland Uni study links climate shifts to soil health in Assam tea gardens", EastMojo, July 28, 2026; "Nagaland University-led study examines impact of climate variability on soil microbes in Assam tea plantations", Morung Express, July 28, 2026; Azariah Babu and others, "Impact of climate change on plantation crops with special reference to tea (Camellia sinensis) in India", Frontiers in Climate, June 8, 2026.