Bahiagrass production and nutritive value as affected by domestic wastewater residuals

Approximately 70% of Florida's biosolids is land-applied with little supporting agronomic information. This experiment was conducted on bahiagrass (Paspalum notatum Flugge), on Pomona fine sand soil (sandy, siliceous, hyperthermic Ultic Alaquods), to compare the agronomic value of aerobically digested slurry biosolid, lime-stabilized slurry biosolid, lime-stabilized cake biosolid, and ammonium nitrate all applied to supply 90 or 180 kg N ha(-1) vs. an unfertilized control. Forage production (3-5 Mg ha(-1)yr(-1)) was similar for the ammonium nitrate and the slurries in 11998 and 1999, highest for the lime-stabilized slurry in 2000, but always 30% lower for the cake biosolid due to the cake's lower N availability. The slurries and ammonium nitrate gave 50% or more forage and higher spring crude protein (CP) concentration (100-170 g kg(-1)) than the control (75-110 g kg(-1)). The CP was improved with ammonium nitrate in early spring, after which, there were no consistent differences in CP or in vitro organic matter digestion (460-600 g kg(-1)) among N sources. Tissue P (2.0-3.5 g kg(-1)), Ca (3.0-8.0 g kg(-1)), and Fe (40-250 mg kg(-1)) were increased by both biosolid slurries in the spring, whereas tissue Cu (6-15 mg kg(-1)) and Mn (10-100 mg kg(-1)) were elevated periodically only by the aerobically digested slurry. Forage was deficient in K and Mn in summer across treatments. Lime-stabilized biosolid could boost bahiagrass production in Florida because it is lower in pathogens, inexpensive, and provides lime and organic matter.