Ranjith Kumar, S., Nepolean, P., Babu, A., Manikandan, K. and Madhumitha, S. (2026) “Impacts of humic acid on soil microbial diversity and productivity in tea cultivation toward sustainable agriculture”, Journal of Plantation Crops, 54(2), pp. 73–79. doi: 10.25081/jpc.2026.v54.i2.10134.