Impithuksa, V., and W.G. blue. “The fate of fertilizer nitrogen applied to three warm-season grasses on a spodosol in florida as indicated by nitrogen-15”. Agriculture and Natural Resources 15, no. 2 (July 1, 1981): 38–45. accessed April 13, 2025. https://li01.tci-thaijo.org/index.php/anres/article/view/240854.