Successive land application of sewage sludge for at least three years followed by no sewage sludge application for at least two years may well be a good practice economically because it will boost and/or maintain sustainable forage productivity and at the same time minimize probable accumulation of nutrients, especially trace metals. Consecutive applications of sewage sludge may result in build up of some trace metals in some other states with initial high metallic content, but in this study, no detrimental effects on soil chemical properties were detected. The possibilities for economically sound application strategies are encouraging, but more and additional research is required to find optimal timing and rates that minimizes negative impacts on soil quality in particular or the environment in general. For proper utilization of sewage sludge, knowledge of the sewage sludges' composition, the crop receiving it, are absolutely crucial, so that satisfactory types and rates are applied in an environmentally safe manner. There is still much to be learned from this study and this investigation needs to continue to determine whether the agricultural and ecological objectives are satisfied over the longer term.

In general, livestock producers face problems associated with the disposal of manures from their animal Amounts of manure generated by concentrated animal operations operations due to limited available land and strict envioften exceed the capacity of nearby land, and stricter environmental regulations lead to creation of pockets of highly impacted sites within ronmental regulations. Moreover, in concentrated ania watershed basin. Linking forage production with manure utilization mal operations, feeds are transported to farms while lack can be an effective approach for addressing both the problems of of manure transportation from the farms has resulted in manure disposal and impact reductions on water quality. In general, H.K. Pant and M.B. Adjei, Univ. of Florida, IFAS, RCREC, 3401 Experiment Station, Ona, FL 33865; J.M.S. Scholberg and C.G. Cham-Thus, their use may lead to accumulations of excess nutribliss, Univ. of Florida, IFAS, Dep. of Agron., Newell Hall, Gainesville, ents, including N and P in soils, and cause potential haz-FL 32611; and J.E. Rechcigl, Univ. of Florida, IFAS, GCREC, 5007ards to water quality. As eco-consciousness increases,

Sewage effluent is essentially clear water that contains low concentrations of plant nutrients and traces of or-Approximately 70% of Florida's biosolids is land-applied with little ganic matter. It is chlorinated to destroy any pathogens. supporting agronomic information. This experiment was conducted on bahiagrass (Paspalum notatum Flugge), on Pomona fine sand soil The solid material remaining after sewage treatment is (sandy, siliceous, hyperthermic Ultic Alaquods), to compare the agro-referred to as biosolids, domestic wastewater residuals, nomic value of aerobically digested slurry biosolid, lime-stabilized or sewage sludge (Kidder, 2001). Wastewater residuals slurry biosolid, lime-stabilized cake biosolid, and ammonium nitrate contain substantial amounts of plant nutrients, traces all applied to supply 90 or 180 kg N ha Ϫ1 vs. an unfertilized control. of heavy metals, and some pathogens (Table 1). Fresh Forage production (3-5 Mg ha Ϫ1 yr Ϫ1) was similar for the ammonium residuals contain 30 to 50 g solids kg Ϫ1 but may contain nitrate and the slurries in 1998 and 1999, highest for the lime-stabilized 200 g solids kg Ϫ1 or more if the material has been deslurry in 2000, but always 30% lower for the cake biosolid due to the watered or dried. For our discussion in this paper, the cake's lower N availability. The slurries and ammonium nitrate gave residuals with 95% or higher water content are referred 50% or more forage and higher spring crude protein (CP) concentrato as slurry biosolid and the drier material as cake biotion (100-170 g kg Ϫ1) than the control (75-110 g kg Ϫ1). The CP was improved with ammonium nitrate in early spring, after which, there solid. were no consistent differences in CP or in vitro organic matter diges-The cow-calf (Bos taurus) industry in Florida depends tion (460-600 g kg Ϫ1) among N sources. Tissue P (2.0-3.5 g kg Ϫ1), Ca almost totally on grazed pastures. Seventy-five percent (3.0-8.0 g kg Ϫ1), and Fe (40-250 mg kg Ϫ1) were increased by both of the 1 million ha of improved pastures in Florida contain biosolid slurries in the spring, whereas tissue Cu (6-15 mg kg Ϫ1) bahiagrasses. Nitrogen is the most limiting nutrient for and Mn (10-100 mg kg Ϫ1) were elevated periodically only by the pasture production so annual inputs of N from organic aerobically digested slurry. Forage was deficient in K and Mn in and inorganic sources are needed to produce adequate summer across treatments. Lime-stabilized biosolid could boost forage. Biosolids are applied to large areas in Florida. bahiagrass production in Florida because it is lower in pathogens, In 1995, 66% of the slurry and cake biosolids from inexpensive, and provides lime and organic matter.

During favorable growing conditions tropical stargrasses (Cynodon spp.) are highly productive, producing more forage than is utilized by cattle under normal stocking rates, and resulting in large amounts of low quality, standing residue. Therefore, grazing trials were conducted to study the effects of three stocking rates (SR) (7.5, low; 10, medium; and 15 cattle/ha, high) on forage yield, quality, utilization and animal performance of three stargrasses: ‘UF‐5’ and ‘McCaleb’ (Cynodon aethiopicus Clayton and Harlan) and ‘UF‐4’ (Cynodon nlemfuensis Vanderyst var. nlemfuensis). Additionally, the medium SR was imposed on “Transvala” digitgrass (Digitmia decumbens Stent.) and “Pensacola” bahiagrass (Paspalum notatum Flugge). The average annual dry matter (DM) yields of stargrasses at low, medium, and high SR and of digitgrass and bahiagass at medium SR were 17.0, 18.3, 20.1, 15.0, and 10.0 metric tons/ha, respectively. In 1976, the in vito organic matter digestibility of digitgrass (51%) and UF‐5 (49%) was superior to that of UF‐4 and McCaleb (46%) stargrass with bahiagrass averaging 46% and 50% in 1976 and 1977, respectively. Crude protein in all entries was similar, averaging 9.9%. Seasonal DM utilization (75 to 95%) of stargrass by cattle was directly related to SR. However, forage intake of 7.6 kg DM/animal/day at the high SR was lower than at the medium (9.3) and low SR (10.2). Forage DM consumed annually (168‐day period) at the medium SR averaged 16.7 metric tons/ha For stargrasses, 14.9 for digitgrass and 9.9 for bahiagrass. Cattle average daily gain (ADG) over seasons ranged from 0.18 to 0.56 kg/dayfor stargrasses, and was an inverse linear function of SR. The ADG measured at a 6‐week interval was a curvilinear function of grazing pressure (GP) with an optimum GP of 6 to 8 kg available forage DM/100 kg body weight/day at 7.5 cm height of cut. Seasonal (168 days) beef gains (2‐year average) on stargrasses were 470, 617, and 576 kg/ha at the high, medium, and low SR, respectively. The ADG and beef product/ha at the medium SR in 1976 on stargrass, digitgrass, and bahiagrass averaged 0.35, 0.28, 0.22, kg/day, 580, 461, and 396 kg/ha, respectively. These data indicated that although ADG is low, high yields of total beef/ha can be obtained with proper stocking rates and correct grazing pressure on stargrass pastures.

Although seed yield of bahiagrass (Paspalum notatum Fluegge) can be increased by burning and N fertilization, there is a need to establish the optimum stage of plant development for the application of such practices. A ‘Pensacola’ bahiagrass pasture, grown on Pomona fine sand (sandy, siliceous, hyperthermic, Ultic Haplaquods), was either burned or mowed at five stages of plant development: dormant, early vegetative, first‐raceme‐visible, and 2 or 4 wk after first‐raceme‐visible. After residue removal, plots were fertilized with 0, 50, or 108 kg ha−1 N. Seed yield, number of inflorescences, seed weight, and seed quality (1987 only) were determined in 1987 and 1988. Stage of plant development at time of residue removal affected all traits (P ≤ 0.05). Seed yield, seed weight, and seed quality were highest when residue was removed at the dormant or early‐vegetative stages of plant development. Seed dormancy, however, decreased as stage of plant development increased. Method of residue removal (burn vs mow) did not significantly (P ≤ 0.05) affect any trait except number of inflorescences in 1987, when more inflorescences were produced following mowing than burning. Nitrogen fertilization significantly (P ≤ 0.05) increased seed yield and number of inflorescences, but had no affect on seed weight or seed quality. Residue removal by burning or mowing prior to the first‐raceme‐visible stage of plant development, followed by application of 50 kg ha−1 N, produced high yields of quality bahiagrass seed.