The-Application-of-Biogas-Sludge-as-Organic-Fertilizer-on-the-Grwoth-of-Spinach-Plant–(Amaranthus-tricolor-L.)- The-Application-of-Biogas-Sludge-as-Organic-Fertilizer-on-the-Grwoth-of-Spinach-Plant--(Amaranthus-tricolor-L.)-