Applied Biosolids (Municipal Sewage Sludge) on Forage Nutrient Concentrations over a Grazing Season in North Florida

Effects of applications of exceptional quality (low toxic minerals), high molybdenum (Mo)containing biosolids (sludge) to bahiagrass (Paspalum notatum) pastures in successive years, or residual effects of applications the previous year, on minerals, crude protein (CP) and in vitro organic matter digestibility (IVOMD) status of forages in north Florida were studied in relation to beef cattle nutrient requirements. Thirty 2acre pastures were assigned one of nine treatments representing two sources of biosolids. Biosolids (Baltimore and Tampa) were applied at an “agronomic rate” (X) and 2X. Four of the treatments represented residual applications of the previous year. Treatments slightly improved calcium (Ca), phosphorus (P), and potassium (K) status of some forages. Little or no difference (P>0.05) was observed between pairs of residual and reapplied treatments. Forage CP concentrations were high and met beef cattle (Angus crossbred) requirements for all treatments. Forage digestibility was similar for all treatments. Forage Mo concentrations were minute, and though some treatment effects were observed (P<0.05), there was no threat of toxic accumulations observed at any time. However, biosolids increased forage S concentrations (>0.4%) which brings about Cu deficiency. Cattle grazing these pastures did exhibit visual signs of Cu deficiency. In relation to beef cattle requirements, the majority of bahiagrass pastures were deficient in sodium (Na), cobalt (Co), Cu, Selenium (Se), and zinc (Zn).