ENHANCING THE SANDY SOIL NITROGEN CONTENT OF THE SAMAS COASTAL AREA USING ANAEROBIC DIGESTION SLUDGE DERIVED FROM PALM OIL MILL EFFLUENT. j Trop. Soils [Internet]. 2026 Sep. 30 [cited 2026 Jul. 16];31(3). Available from: https://journal.unila.ac.id/index.php/tropicalsoil/article/view/665