“Ammonia Volatilization from Urea As Affected by Humic Substances Derived from Palm Oil Mill Effluent (POME) and Tropical Peat. (13)”. Tropical Agriculture 77, no. 1 (January 30, 2000). Accessed September 17, 2024. https://journals.sta.uwi.edu/ojs/index.php/ta/article/view/1431.