Sewage Sludge as an Alternative Fertilizer for Tropical Pasture Grasses

This study was conducted to determine the effects of source (Liquid sludge at pH 7 (LS7) or pH 11 (LS11), cake biosolid (CB) or ammonium nitrate (AM)) by rate (0, 80 or 160 kg ha-1) of N application on bahiagrass forage yield, quality and tissue composition. Same plots were fertilized in March 1998 and 1999. Forage yield was measured at 30 d intervals from May through November and subsamples were dried and ground for quality analyses. The 2-year mean forage yield was similar for AM, LS7 and LS 11 fertilizer applications. Forage yield from CB application was 30% lower than yield from other N sources at comparable N rates. Forage crude protein content was highest for the AM treatment only during the initial harvest. Tissue concentrations of plant nutrients were increased by organic sources of fertilizer. These results, in conjunction with data from soil and groundwater analyses, suggest that processed domestic septage could be a safe and inexpensive substitute to inorganic fertilizer for tropical pasture grasses