Sewage sludge is being converted to compost by many municipalities. Its use in the production, establishment, and/or maintenance of horticultural crops is dependent on soluble salt concentration, particle size, stability, dewatering procedures, storage conditions, and crop needs. Soluble salt concentration has the greatest effect on the amount of compost that can be used as a soil or potting media amendment. Because composted sewage sludge is rich in plant nutrients, it can supply many of the nutrient needs of plants, depending on the amount used and if the plants are growing in the ground or in containers. However, improper storage of composted sewage sludge can render the product useless due to the accumulation of acetic acid and alcohol that occur under anaerobic conditions.
Francis R. Gouin
Robert F. Bevacqua and Valerie J. Mellano
Compost made from sewage sludge (40% by volume) and chipped trimmings of Eucalyptus trees (60%) was evaluated as a soil amendment for the field. production of onion (Allium cepa cv. Spanish Sweet Utah), lettuce (Lactuca sativa cv. Black Seeded Simpson), snapdragon (Antirrhinum majus cv. Sonnet Yellow), and turfgrass (Festuca arundinacea cv. Marathon). Turf shows a strong reponse to preplant compost applications and is relatively tolerant of the buildup of soluble salts that can occur with compost applications. Also since it is not a food crop the possible uptake of heavy metals is not a major concern. These results indicate the amending of soil for the planting of turf is a likely commercial use of the compost. The authors are presently evaluating the use of the compost as a top dressing on turf plantings.
S. A. Mackintosh and R. J. Cooper
Environmental concerns associated with traditional methods of sludge disposal have spurred research exploring alternate avenues of disposal. A potentially significant alternative is the beneficial use of sludge as a turfgrass fertilizer. Studies were initiated during 1991 to compare a commercially available pelletized sludge to urea; 12-4-6; Ringer Lawn Restore; and Milorganite. Fertilizers were evaluated for their effect on turfgrass quality, color, and growth rate. Treatments were applied to a stand composed of 65% Kentucky bluegrass (Poa pratensis L. `Baron') and 35% Perennial ryegrass (Lolium perenne L. `Manhattan II') in South Deerfield, MA. Urea and 12-4-6 were applied at 49 kg N ha-1. Ringer Lawn Restore and Milorganite were applied at 98 kg N ha-1. Pelletized sludge was applied at 98, 196, 294, and 392 kg N ha-1 with all rates providing acceptable to good turfgrass color throughout the season. Rates of 294 or 392 kg seldom provided quality better than the 196 kg rate. While urea initially produced quality superior to pelletized sludge, all rates of sludge resulted in quality equal to or better than urea beginning one month after application and lasting approximately 11 weeks. Turf receiving similar rates of either pelletized sludge or Milorganite performed similarly. No sludge application rate produced burning or foliar discoloration. Clipping production was directly related to sludge application rate. Pelletized sludge applied at 98 kg N ha-1 resulted in growth comparable to similar applications of Ringer Lawn Restore and Milorganite. In summary, using pelletized sewage sludge as a turfgrass fertilizer promotes healthy turfgrass while creating an alternate avenue of sludge disposal.
Valerie J. Mellano and Robert F. Bevacqua
Municipal sewage sludge, previously amended with Eucalyptus tree trimmings and composted, was incorporated to a depth of 30 cm at rates of 0, 12.3 and 24.6 dry MT/ha for a field planting of onion, snapdragon, turf and spinach. In a similar subsequent planting, the sludge compost was incorpoated to a depth of 10 cm. Additional treatments address the residual effect of the material. The results indicated sludge compost incorporated to a depth of 30 cm had no effect on crop yields, but when incorporated to a depth of 10 cm there was a significant increase in yields for all test crops. No buildup of heavy metals, soluble salts or changes in soil pH that would depress crop growth were detected.
Two greenhouse experiments employed equivalent rates and the same four crops. Two materials, sludge compost and heat-dried sludge were compared. The former contained composted Eucalyptus tree trimmings. The latter did not. The results showed both materials were equally beneficial to crop growth and the presence of Eucalyptus trimmings did not decrease yields
Michael D. Orzolek and John H. Murphy
A long term study was initiated in 1993 to evaluate the effect of composted sewage sludge on growth, yield, and quality of different vegetables. The composted sewage sludge consisting of 40% hardwood sawdust and 60% clean municipal wastewater sludge was obtained from the University Area Joint Authority (UAJA) in State College, PA. The composted sewage sludge is currently sold by UAJA as a fertilizer amendment under the name CornposT. Two rates of the ComposT product (11 and 22 dry T/A) were compared to a granular fertilizer application of 800 lbs/A of 10-10-10. The low rate of ComposT also received half of the fertilizer rate. After incorporation of the amendments into a Hagerstown clay loam soil, lettuce, tomato, muskmelon, cabbage and pepper were transplanted in the field in a Randomized Block Design with 3 replications. ComposT application did not reduce yield or quality of cabbage, lettuce tomato,and muskmelon; in fact, yields were generally higher with the application of composted sewage sludge. The application of ComposT did not reduce the macro or micro nutrient concentration of leaf tissue below optimum levels nor did it result in any phytotoxic effects in plant growth. In addition, the application of ComposT did not increase the heavy metal (Cd, Ni, Pb) concentration in leaf tissue or increase the risk of microbial contamination in the edible portion of the vegetables.
David Devenney, John Frett, Wallace Pill and Gary Smith.
Ten 10 wildflower species grew satisfactorily in a 1:1 (vol.) mix of Ironrich (IR, mineral co-product of the titanium dioxide industry) and Fairgrow (FG, co-composted sewage sludge and solid waste). Shoot fresh weights in the low fertility IR and in the high fertility FG averaged 35% and 157%, respectively, those grown in IR+FG. Wildflower establishment in 10cm-deep outdoor seedbeds of IR, FG, or IR+FG were compared to those in soil (control) plots. Maximum percentage seedling emergence and emergence rate and synchrony were lower in FG than in IR, values in IR+FG being intermediate and similar to those for control plots. Shoot fresh weights, however, were greater from the IR+FG than from IR, FG or the control plots. Total shoot dry weights of wildflowers from 1 m2 subplots after 3 months were FG > IR = IR+FG > control, being respectively 8.4, 8.5, 5.1 and 1.1% those of total shoot dry weights of weeds.
M. Ozores-Hampton, H.H. Bryan, B. Schaffer and E.A. Hanlon
The effects of municipal solid waste (MSW) materials on growth, yield, and mineral element concentrations in tomato (Lycopersicon esculentum Mill.) (1991 and 1992) and squash (Cucurbita maxima Duch. Ex Lam.) (1992 and 1993) were evaluated. Agrisoil compost (composted trash), Eweson compost (co-composted trash and sewage sludge), or Daorganite sludge (chemically and heat-treated sewage sludge) were incorporated into calcareous limestone soil of southern Florida. The control had no MSW material added to the soil. The effect of MSW on crop growth, yield, and mineral element concentrations varied considerably between years for tomato and squash. In 1991, tomato plants grown in soil amended with Eweson or Daorganite had a greater canopy volume than plants in the control treatment. Tomato plants grown in Daorganite had greater total fruit weight (1991) than plants in Agrisoil and more marketable fruit (1992) than control plants. In both years, tomato plants in Agrisoil had higher root Zn concentrations than plants in the other treatments. In 1992, tomato plants in Eweson had lower root Mn concentrations than plants in the other treatments, whereas Mg concentrations in the roots were higher in the Daorganite treatment than in Eweson. Tomato plants in Agrisoil had higher Pb concentrations in the roots than plants in all other treatments. In 1991, leaves of tomato plants in Agrisoil had lower Ca concentrations than leaves of plants in the control treatment. In 1992, leaf Zn concentrations were greater for tomato and squash in Agrisoil than in the control or Daorganite. In 1992, canopy volume and yield of squash were greater for plants in Daorganite than for plants in the control and other MSW treatments. Although canopy volume and total squash fruit weight did not differ among treatments in 1993, plant height was greater for squash plants in the MSW treatments than for those in the control. In 1993, leaf Mg concentrations were greater for squash grown in Daorganite than for plants in the control or Agrisoil. In 1993, fruit Cd concentration was higher for plants with Eweson than for plants in the control or Agrisoil. However, the fruit Cd concentration in squash grown in Eweson compost (1.0 mg/kg dry weight) was far below a hazardous level for human consumption. Our results indicate that amending calcareous soils with MSW materials can increase growth and yield of tomato and squash with negligible increases in heavy metal concentrations in fruit.
Douglas T. Linde and Lawrence D. Hepner
Using composted biosolid waste as a soil amendment for turfgrass is becoming a common method for disposing of municipal waste. This study was conducted to evaluate turfgrass seed and sod establishment on subsoil amended with various rates of biosolid compost. To a soil that had its A-horizon removed, biosolid compost derived from sewage sludge was incorporated at rates of 0, 132, 270, and 402 yard3/acre. A fifth treatment included a single application of fertilizer at time of sowing. Kentucky bluegrass (Poa pratensis) was seeded immediately after treatment application. The treatments were repeated on an adjacent area using kentucky bluegrass sod. For 1.5 years, turfgrass percent cover, color, density, and weeds were evaluated. Overall, the compost performed well as a soil amendment for turfgrass. A 2- to 3-inch depth of compost appeared to be the best incorporation rate for the soil and compost used in this study. High salinity and excessive ammonium nitrogen (NH4-N) levels in the compost-amended soil at the time of establishment caused a 2- to 3-week delay in seed and sod establishment. After the 2 to 3 weeks, the compost-amended plots outperformed the one-time fertilized plots in turfgrass color and density. Turf managers may want to account for the delay in establishment when incorporating a 60-day-cured compost.
Mike Litvany and Monica Ozores-Hampton
Commercial citrus (Citrus sp.) groves in Florida use an average of 150 lb/acre (168 kg·ha-1) of elemental nitrogen (N) per year. There are about 853,000 acres (345,000 ha) of commercial citrus requiring about 63,975 tons (62,652 t) of N. At an average analysis of 12% N, about 533,125 tons (483,811 t) of blended nitrogenous fertilizers are applied to citrus annually. To meet this annual N demand from compost, it would be necessary to produce 3,198,750 tons (2,901,906 t) of 2% N compost. The market for high-quality compost products in Florida is far greater than the current or projected production capacity of the state. As long as the cost benefits of compost are clear to citrus growers, demand will always exceed supply. Not all composts are equal in their nutrient availability. The best composts for use as fertilizers are derived from sewage sludge or biosolids, municipal solid waste and sludge, food waste, and/or animal manure combined with a bulking agent such as sawdust or wood chips. Composts made from wood waste as their only feedstock contain large amounts of lignin and cellulose to break down within a reasonable period to directly offset chemical fertilizers. Ultimately, they will mineralize in the soil and provide all of the benefits described earlier, but their rates of availability are in years rather than months, like the other composts.
Nancy E. Roe, Peter J. Stoffella and Herbert H. Bryan
Increasing disposal problems with polyethylene (PL) mulch and greater availability of compost prompted an investigation into the effects of using compost as a mulch on horizontal raised bed surfaces with living mulches (LMs) on vertical surfaces. Wood chips (WC), sewage sludge-yard trimming (SY) compost, and municipal solid waste (MW) compost were applied at 224 t·ha-1 on bed surfaces. Sod strips of `Jade' (JD) or `Floratam' (FT) St. Augustinegrass (Stenotaphrum secundatum Kuntze) or perennial peanut (Arachis glabrata Benth.) (PP) or seeds of a small, seed-propagated forage peanut (Arachis sp.) (SP) were established on the vertical sides of the raised beds before transplanting bell pepper (Capsicum annuum L.) into the beds. Phytophthora capsici reduced pepper plant stand in PL-mulched plots compared with organic mulch (OM) and LM. Despite the stand reduction, total pepper yields were highest in PL plots and, in the OM plots, decreased in the order SY > MW > WC. Early fruit yields and yield per plant were highest from plants in PL plots followed by SY. Among LMs, plants in SP plots produced highest early yields and FT produced the lowest. Plants in PL plots produced the largest fruit. When the same plots were seeded with winter (butternut) squash (Cucurbita pepo L.), plant stands were higher in MW than WC and SY. Squash yields were similar between PL and OM plots.