Composting of Yard Waste and Wastewater Treatment Plant Sludge Mixtures

Composting of yard waste and sludge/yard waste mixtures was investigated during laboratory and field testing. A strong correlation between moisture content and windrow peak temperatures was observed. Odors were detected at cocomposting windrows when temperatures exceeded 54°C. The sludge to yard waste mixture ratio was found to affect resulting compost particle size and, consequently, oxygen transport. Compost quality was excellent, with pesticides below detection level and low concentrations of heavy metals.     

Wood Ash as an Amendment in Municipal Sludge And Yard Waste Composting Processes

Wood ash from a wood-fired, electrical generating plant was examined as a potential amendment in municipal biosolids and yard waste composting applications. The rate of composting and the final compost quality (chemical, physical, and plant growth characteristics) were examined. Yard waste (leaves, grass, and wood chips) and a municipal biosolids-chip mixture were either not amended or amended with wood ash at eight percent or five percent by weight, respectively, and then composted outdoors in insulated, 1700L, aerated reactors. Yard waste piles heated rapidly to 60°C within six to seven days, whereas biosolid piles heated more slowly to a maximum of 52 to 57°C within nine to 11 days. Ash had little, if any, effect on the time-temperature response. In general, ash-amended compost had higher pi I, plant nutrient, and salt contents. Tomato plants (Lycopersicum esculentum) produced 100 percent more shoot biomass in biosolids than in yard waste compost media. Poor plant growth in the yard waste compost was likely due to the high initial pH and salt content of the growth medium. In yard waste media, tomato plants germinated and produced more shoot biomass in the control compost than in the ash-amended compost.

A pH neutralization study indicated that wood fly ash could be used as an economical substitute for lime which is commonly used to stabilize municipal biosolids prior to land filling or land application. Wood fly ash (pH = 13.2-13.4), when added to biosolids at a 2 to 1 ratio by weight, raised the pH of the mixture to 12.0.     

Pesticide Screening in a Commercial Yard Waste And Biosolids Compost

The presence of pesticides in compost is of interest because of possible health, production and ecological risks. The presence of over 50 pesticides was assessed in raw yard waste, milled yard waste, and a finished compost (yard waste:biosolids) at a commercial compost facility in Florida. These pesticides were comprised of 38 herbicides, eight insecticides and two fungicides. Of the pesticides monitored for in this study, only atrazine, 4,4-DDE, alpha chlordane, gamma chlordane, and endosulfan I were detected, and were only present in raw yard wastes.     

Effects of Compost Source and Timing of Fertigation Initiation on Growth of Potted Poinsettia

Treatment combinations of four poinsettia (Euphorbia pulcherrima) cultivars, 20 substrates, and three fertigation treatments were evaluated in a completely randomized block design. Poinsettia cultivars included ‘V-14 Glory’, ‘Red Sails’, ‘Lilo Pink’, and ‘Annette Hegg Top White’. The compost substrates were compost:peat:perlite blended (by vol.) at 2:3:3, 1:1:1, and 2:1:1 ratios. Sunshine Mix 1 and Pro Gro 300S were used as controls. Composts tested were those prepared from crab offal, lime and polymer-dewatered biosolids, municipal solid waste (MSW), yard waste, and poultry litter. Fertigation treatments were initiated on the week of potting, delayed one or two week after potting and applied once per week. Controls produced premium quality plants. Composts prepared from poultry litter, yard waste, polymer-dewatered biosolids, crab offal, and MSW produced good quality plants. Plant width in 25 percent compost treatments were greater than those in 50 percent compost treatments. Total number of branches, plant height, canopy diameter, and plant grade on plants treated with fertilizer on the first week were only three percent greater than in treatments where fertilizer application was delayed one or two weeks.     

Regeneration of Nitrogen Fertility In Disturbed Soils Using Composts

Soil disturbance often results in loss of soil organic matter and nitrogen (N) fertility, making revegetation of barren areas difficult. Yard waste composts are a potential source material to regenerate soil fertility so that revegetation success is improved. The N release behaviors of several compost materials produced within California were evaluated during a long-term, 586-day aerobic incubation. Two general types of compost were tested, including yard waste compost materials (lawn clippings and chipped brush) and cocomposted materials (biosolids bulked and composted with yard waste materials). Nitrogen release from composted material was measured using periodic soil solution extraction and soluble N analysis. Nitrogen release rates varied widely between source materials during the initial portions of the incubation period, with cocomposts having much greater release rates than the yard waste composts. Yard waste composts that were poorly cured or had high woody fiber content showed net immobilization of N during the initial incubation periods, which could potentially lead to N-limitations for plant growth in field conditions. Following additional curing in the soil, however, all yard waste compost materials had positive net N mineralization release rates. Release rates were similar to some of the native soils used as reference materials. The relationship of long-term aerobic N release and several other indicators of mineralizable or “bioavailable” N were evaluated, but the relationship of these other indicators with the aerobic incubation data was low. Because the cumulative N release from yard waste compost materials was a small fraction of the material's total N content, N leaching losses in field conditions are expected to be small and of short duration. Steady, long-term N release patterns were observed from composts throughout the second half of the study and would be expected to continue for an extended period in the field. Composts are shown to provide a suitable replacement source of slowly available N for plant establishment on drastically disturbed, low nutrient soils.     

Growth of Impatiens ‘Accent Red’ In Three Compost Products

Growth of Impatiens wallerana Hook. ‘Accent Red’ was evaluated in three composted urban waste materials (composted biosolids and yard trash (SYT): 20 percent biosolids/sewage sludge, 44 percent yard trimmings, and 36 percent mixed paper; composted refuse fuel residues with biosolids and yard trash (RYT): 74 percent refuse-derived fuel residuals, 10 percent biosolids/sewage sludge, and 16 percent yard trimmings; and composted municipal solid waste (MSW): 100 percent municipal solid waste). Treatments consisted of 100 percent composted waste and media in which the composted wastes were combined with control medium components at 60 percent, 30 percent, or 0 percent composted waste, by volume. Shoot dry mass of plants grown in SYT increased as the percentage of SYT in the medium increased, while shoot dry mass of plants grown in MSW linearly decreased from 1.24 g to 0.15 g. There were no significant differences in shoot dry mass of plants grown in different percentages of RYT. Initial medium soluble salt concentrations in MSW media were more than double concentrations measured in SYT and RYT media. Soluble salt concentrations in both the 100 percent and 60 percent MSW media exceeded 1.75 dS.m^?1, while the soluble salt concentrations in 100 percent SYT and 100 percent RYT were 0.50 dS.m^?1 and 0.61 dS.m^?1, respectively. The C:N ratios in 100 percent SYT and RYT were 17 and 15, respectively, while 100 percent MSW had a C:N ratio of 29. The relatively higher level of compost maturity as indicated by lower C:N and soluble salt concentrations contributed to superior growth of impatiens plants in 100 percent SYT and RYT compared to 100 percent MSW.     

Mineralization and N Fertilizer Equivalent Value of Composts as Assessed by Tall Fescue (Festuca arundinacea)

The capability to determine nitrogen availability of composts is necessary to ensure that such materials will provide sufficient fertilization to the growing crop and cause minimal environmental degradation. A greenhouse study using tall fescue as a bioindicator was used to evaluate nitrogen availability of two biosolids composts, two mixed yard waste-poultry manure composts, and one commercially-processed poultry litter. Five inorganic nitrogen (as NH₄NO₃-N) treatments applied at 0, 22.5, 45, 67.7, and 90 mg N/kg soil were employed to establish an N calibration curve. Yield, fescue biomass total nitrogen (as total Kjeldahl N (TKN)), and soil TKN and KCl extractable NO₃^?-N and NH₄⁺-N concentrations of the organically amended treatments were compared to the inorganically fertilized treatments to determine amendment N mineralization rates and N fertilizer equivalent values (NFEV). Nitrogen mineralization rates were greatest in the poultry litter (21%) and Panorama yard waste compost (5%) amended pots. The NFEV of these amendments were 49% and 10%, respectively. Wolf Creek biosolids compost and Huck's Hen Blend yard waste compost immobilized N (?5% and 0.18%, respectively), and had percent NFEV of ?0.66% and 0.19%, respectively. Rivanna biosolids compost immobilized N (?15%), but the NFEV was 30% due to the relatively high inorganic N content in the amendment. Nitrogen mineralization and NFEV were generally greater in amendments with greater total N concentrations and lower C:N values. The total N concentration and C:N values were less reliable variables in predicting N mineralization and percent NFEV when a significant portion of the total N was in the inorganic form. Nitrogen equivalency value and N mineralization for each amendment increased with time of sampling, indicating the potential for early season N insufficiency to plants fertilized with compost due to lack of synchrony between N mineralization and plant N needs.     

Poultry Residual Composts: Materials Balance and Crop Response

This paper discusses compost production yields as a percent of raw product mix using poultry litter, poultry processing plant dissolved air flotation skimmings, sawdust, wood chips and ground yard debris. Three different mixes were used and identified as Mixes 1, 2 and 3. Mixes 1 and 2 were produced using windrows and a windrow turner and Mix 3 was made using a covered in-channel compost turner. Mixes 1 and 2 were poultry litter compost with a screened mass yield of 80 and 77 percent, respectively. Mix 3 was a dissolved air flotation compost with a screened mass yield of 40 percent. Results from plant experiments show poultry litter compost can be used successfully in potting mixes for poinsettia and chrysanthemum production. A compost produced from dissolved air flotation skimmings, a poultry processing waste, can be used in field corn production but had little influence in the production of soybeans.     

Effects of Compost Sources and Seeding Treatments on Germination and Emergence of Four Turfgrass Species

Greenhouse pot trials were conducted to compare the effects of compost sources and planting treatments on turfgrass germination and emergence. Eight seeding treatments and 4 turfgrass types were factorially combined and replicated four times in a completely randomized block design. The seeding treatments were: 1) seed planted on surface of 2.6 cm compost overlying soil, 2) seed planted on soil surface below 0.65 cm compost, 3) seed planted on soil surface below 1.3 cm compost, 4) seed planted on soil surface below 2.6 cm compost, 5) seed planted on soil surface covered with a 2.6 cm straw mat, 6) seed planted below 1.3 cm soil, 7) seed planted below 1.3 cm of 1:1 compost:soil mix, and 8) seed planted on soil surface. Tall fescue (Festuca arundinacea Schreb.), Kentucky bluegrass (Poa pratensis L.), bermudagrass (Cynodon dactylon L.), and zoysiagrass (Zoysia japonica Steud.) were used as the bioassay crops. The experimental design was repeated over time using composts produced with the following feedstocks: yard waste, food waste, dairy manure, biosolids, and paper mill sludge. Emerged seedlings were counted at 11 days for tall fescue, at 3 weeks for Kentucky bluegrass and at 7 weeks for bermudagrass and zoysiagrass. There were significant (P<0.05) effects of seeding treatment x turfgrass type on germination and emergence for each compost type. All of the composts appeared to be well stabilized using routine compost laboratory testing except the biosolids compost, whose use resulted in the lowest overall germination and emergence rate. The highest rates of germination and emergence occurred in the treatments in which the seeds were planted on the surface, regardless of whether the surface was compost or soil. The lowest rate of germination and emergence occurred where the seed was placed under 2.6 cm compost, regardless of compost maturity.     

Stability Evaluation of Mixed Food Waste Composts

As interest in food waste composting grows, so does the need for proven composting methods. Stability testing has been proposed as a compost quality assurance tool. We conducted this study to: (i) to evaluate the efficacy of simple outdoor composting methods in producing a compost with a low, stable decomposition rate, and (ii) to determine the reliability of simple, 4-h compost stability evaluation methods. Composting was conducted outdoors in winter and spring in Eugene, Oregon without moisture addition. Mixed food waste was combined with screened dairy solids and ground yard trimmings. Sawdust was used to cover windrows for the first 27 d of composting. Compost windrow temperatures remained above 55°C for 30+ d. Carbon dioxide evolved with several 4-h test methods was strongly correlated (r² > 0.7) with CO₂ evolved using a 48-h test. A limited-turn windrow (LTW) composting system produced compost with slightly greater stability than a passively aerated windrow (PAW) composting system. Food waste compost samples had a low CO₂ evolution rate after 71 to 99 d using either composting system. Compost CO₂ evolution rate at 25°C decreased with composting time, reaching approximately 1 to 4 mg CO₂-C g compost C^?1 d^?1 for the PAW method and 0.5 to 2 mg CO₂-C g compost C^?1 d^?1 for the LTW method. Putrescible organic matter in food waste was effectively decomposed in outdoor windrows using composting methods that did not employ forced aeration, self-propelled windrow turners, or manufactured composting vessels. Several 4-h stability tests showed promise for implementation as quality assurance tools.     

Heavy Metals in Soil Treated with Sewage Sludge Composting, their Effect on Yield and Uptake of Broad Bean Seeds (Vicia faba L.)

The final use that may be given to biosolids that result from the treatment of residual municipal waters depends on their physicochemical and microbiological characteristics. Their organic matter content and wealth of essential elements may allow their use for agricultural fertilization purposes. The objective of this research project was to evaluate the physicochemical interactions between soil treated with biosolids and compost from municipal residual waters, and the nutritional parameters of broad bean seeds (Vicia faba L.). The studied area is located in the central region of the Mexican Republic. The biosolids were treated with aerated static pile composting. The experimental work was performed in the area surrounding the East Toluca Macroplant, where nine 2 × 3 m plots were defined and distributed in a Latin square; 3 plots were used as controls (without conditioning), 3 were conditioned with 4.5 Mg ha^?1 of biosolids on a dry base, and 3 were conditioned with the same amount of compost. The parameters determined for biosolids, compost, and soil were: pH, electrical conductivity (EC), organic matter (OM), total nitrogen, available phosphorus, cation exchange capacity (CEC), exchangeable cations (Ca, Mg, Na and K), total and available heavy metals (Cd, Cr, Cu, Ni and Zn); for the plant: height reached, green seeds productivity and yield per treatment (ton ha^?1); for the seeds: humidity, ashes, fiber, fats, protein, starch and total and available heavy metals (Cd, Cr, Cu, Ni and Zn). pH was slightly acid in soil treated with biosolids (6.71). OM and CEC did not represent significant differences. Total concentrations of Cr, Zn, Ni and Cu in soil presented significant differences (p < 0.05) between treated soil and the control, Cd was not detected. Cu was the most available metal in soil treated with compost (15.31%), Cd and Cr were not detected. The plants had higher growth rates with biosolids (112.22 cm) and compost (103.73 cm); higher green broad bean productivity and higher seed yield, especially in plots containing biosolids, which had rates three times higher than the control. In regards to broad bean seeds, content of ashes, fiber, fats, protein, starch and heavy metals (Cu, Ni and Zn), there were no significant differences between the treatments. Cd and Cr were not detected. In conclusion, it has been proven that the use of biosolids and compost studied in this broad bean crop do not involve an environmental risk, and thus give way to a solution to the problem of final disposition of biosolids in the region.     

Effects of Turning Frequency,Leaves to Grass Mix Ratio and Windrow vs. Pile Configuration on the Composting of Yard Trimmings

Because of proposed bans on the landfilling and incineration of leaves, grass and brush, large-scale composting is fast becoming the primary disposal option for yard trimmings in many states. Few systematic studies have been done to compare the effects of turning regime, feedstock mix ratio, or windrow vs. pile configuration on composting and the characteristics of finished compost. In this study, various ratios of leaves, grass and brush were mixed and composted in two series of windrows; and one set of static piles. One windrow series (#1) was turned seven times every four weeks, while the other windrow series (#2), and the piles, were turned once every four weeks. The effects of the different treatments were examined by measuring compost temperature, oxygen concentration, pH, organic matter and moisture content, volatile fatty acid content, bulk density, stability, humification and seed germination indices, total and available nutrient levels, and particle size distribution. Results showed that turning frequency had little impact on oxygen concentrations, VFA content and temperatures during the composting of yard trimmings in windrows, however, in piles temperatures were substantially higher and oxygen concentrations fluctuated greatly. The composts from all the treatments were stable, (oxygen uptake rates < 0.1 mg O₂/g OM/hr) after 60 days of composting regardless of the turning frequency, mix ratio or configuration. The bulk density inereased much more rapidly in frequently turned windrows than in the other treatments and particle sizes were smaller in these windrows. In most respects however, the final composts (day 136) were remarkably similar and none inhibited Cress seed germination or root elongation. The pH of all the composts, and the soluble salts and nitrate levels in composts made with high levels of grass, exceeded guidelines for greenhouse growth media.     

Prolonged compost curing reduces suppression of Sclerotium rolfsii

Composts have long been recognized to facilitate biological control of soil borne plant pathogens. Composts can introduce biocontrol agents into growth media and serve as a food base for their establishment and activity. Mature biosolids compost (a blend of sewage sludge and yard waste) was found to be suppressive to germination of the sclerotia of S. rolfsii on compost plates and also suppresses the disease development in bean plants (Phaseolus vulgaris L.). Microscopic observations revealed that sclerotia placed on suppressive compost were attacked by mycoparasites. However, prolonged curing of compost negated this phenomenon. This research was aimed to study the changes in chemical and biological properties occurring during prolonged curing and their relation to compost suppressiveness. Correlations were found between the decrease and subsequent loss of suppression of sclerotia germination and the decrease in basal respiration, dissolved organic carbon (DOC) and concentrations, and the increase in concentration and specific UV absorbance. A shift of both bacterial and Ascomycetes populations as a consequence of curing was observed. Interactions between micro-organisms and their chemical environment are discussed.     

In-Vessel Cocomposting of Green Waste With Biosolids and Paper Waste

In comparison to traditional windrow composting, in-vessel composting techniques often represent more effective waste management options due to the reduced production of bioaerosols and leachate and the potential for better process control. Chemical processes occurring during the cocomposting of three common wastes (green waste, biosolids and paper processing waste) were studied using the forced aeration, static pile, in-vessel EcoPOD® composting system. Since no turning of the compost occurs within the static piles, spatial differences in the vessel were also monitored. These measurements revealed significant spatial gradients in temperature; however, this did not result in spatial differences in nutrients within the composting vessel. Significant differences in soluble N production were observed during the composting process following the series: green plus paper waste < green waste < green waste plus biosolids. After the active compost phase was over, and the compost was removed from the vessel and matured outside, we demonstrated that covering the compost was essential to preserve compost quality. Our study clearly shows that cocomposting of common waste feedstocks can be used to successfully manipulate the chemistry of the final compost making it suitable for multiple end uses. In addition, our study demonstrated that careful management of the compost maturing phase is also required to maximise quality and minimize pollution.     

Nutritional Values of Some Biowastes As Soil Amendments

As a result of increased population, improved standards of living, and strict environmental laws, biowastes have been generated in huge quantities. Thus, land applications of these wastes are desirable, or even necessary, to keep the environment healthy and to conserve natural resources. Yet, the success of such uses requires knowledge of complex biochemical reactions when the wastes are applied to soils. To obtain this knowledge, we evaluated soil amendment properties, primarily nitrogen (N) mineralization/immobilization of six bio wastes when used as plant growth media. An immature yard trimmings compost, ground fresh corn stovers, a commercial peat moss, a chicken manure, and two biosolids were each mixed with a Mollisol at either 25 percent and 50 percent by volume for the plant based wastes, or at 2.5 percent and 5.0 percent by weight for the animal based wastes. Treatments with urea at 0, 70 and 210 mg N kg^?1 were included for comparison. The treated soils were incubated moist for two weeks at which time they were sampled for chemical analysis, and planted to tomatoes. The results showed that those wastes, when added to soil, produced growth media with C/N < 15, and released inorganic N that increased dry matter yield of tomatoes many times over that of the unamended control. In contrast, a waste amended soil with a C/N > 20 immobilized some inorganic N, reduced plant growth, and caused N deficiency in tomatoes. Such a deficiency was characterized by low N concentrations in leaves (< 2.0 percent) and chlorosis, which corresponded to a color index of 0.25 or less. Biowaste amendments also affected soil P extractability differently: Chicken manure increased NaHCO₃-extractable P many fold over the control, whereas corn stover, peat moss and raw biosolids did not. The yard trimmings compost and the anaerobically digested biosolids increased soil P moderately.     

Growth of Ornamental Plants in Container Media Amended with Biosolids Compost

The use of biosolids compost, in the formulation of media used in the commercial production of container grown nursery crops, has been slow in the Northeast region of the United States. When biosolids compost is used in growing media, it is limited to small percentages. Regulations in Connecticut restrict the use of most biosolids compost to growing media for containerized ornamental plants and landfill cover. Information on the benefits of using biosolids compost, to grow a wide range of plant species in containers, could increase usage by nurseries. Seven species of flowering annuals, nine species of herbaceous perennials and eight species of woody ornamentals were grown in media containing 0, 25, 50, and 100 percent (by volume) biosolids compost, in combination with a mixture of bark, peat and sand. Biosolids compost came from the Metropolitan District Corporation (MDC) facility in Hartford, Connecticut. It was a mixture of wood chips and digested biosolids (3:1 by volume). Optimal plant growth generally occurred in media containing 50 and 100 percent compost. Plants growing in media high in compost were often somewhat stunted and chlorotic for several weeks after planting probably due to higher levels of salinity and ammonium nitrogen in their media. However, by the middle of the growing season these plants had recovered and at season's end, they were often superior to plants grown in media with less compost. Increasing proportions of compost generally increased the amounts of plant nutrients and heavy metals in media while decreasing air filled pore space. All heavy metal concentrations were below levels of concern.     

Effect of compost on erodibility of loamy sand under simulated rainfall

Three types of composts [vegetable, fruit and yard waste compost (VFYW), garden waste compost (GW), and spent mushroom compost (SM)] were applied at a rate of 30 m³ ha⁻¹ for 10 years to loamy sand, to determine its effect on the aggregate stability and susceptibility to water erosion. Aggregate stability was measured using the stability index derived from the wet sieving method while a laboratory rainfall simulator was used to measure runoff, sheet and splash erosion. Only GW recorded a significant increase (45%) in aggregate stability. Runoff, sheet erosion, and splash erosion did not show significant improvement for any of the compost types. SM application resulted in a significant increase (51%) in the shear strength of the soil after rainfall. Long term compost application does not appreciably improve the resistance of loamy sand to water erosion.     

Cocomposting biosolids and municipal organic waste: effects of process management on stabilization and quality

The quality of compost made from the organic fraction of municipal organic waste (MOW), in terms of organic matter and nutrient concentrations, is inferior to that of compost from other feedstocks. The aim of this work was to improve the quality of MOW compost by means of cocomposting with biosolids (at ratios of 1:1, 2:1, and 3:1 MOW/biosolids) and vermicomposting. Vermicomposting (ground beds with worms) treatments were prepared from traditional pile material after 40 composting days; ground beds without worms were also included. Several parameters, including pH, electrical conductivity, carbon dioxide production, organic matter, total nitrogen, water-soluble carbon, nitrate, ammonium, and extractable phosphorus, were measured throughout the process. Organic matter in the products at 120 days ranged between 39 and 45%, whereas total nitrogen was between 1.7 and 2%. Considering these parameters, the quality of MOW and biosolids cocompost was better than that of MOW composted alone in a previous study (18% organic matter and 0.7% total nitrogen concentration). Extractable phosphorus was also greatly increased from 128 mg/kg in MOW compost to 542–722 mg/kg in the cocompost. Of the three MOW/biosolids ratios employed, only the 2:1 and 3:1 mixtures were adequate for composting and produced similar product qualities. However, the 2:1 mixture required more turnings and exhibited higher N losses. The improvement of quality by vermicomposting was limited. Compared to traditional piles, it did not affect concentrations of organic matter or total nitrogen. The direct action of worms, measured by comparing ground beds with and without worms, increased nitrate concentrations for mixtures 2:1 and 3:1 and extractable phosphorus concentrations for mixture 3:1.     

Comparison of Herbaceous Perennial Plant Growth in Seaweed Compost and Biosolids Compost

Liners of angelonia ‘Pink’ (Angelonia angustifolia Benth.), shooting star (Pseuderanthemum laxiflorum), coreopsis ‘Early Sunrise’ (Coreopsis grandiflorum Hogg ex Sweet.), and scutellaria ‘Purple Fountains’ (Scutellaria costaricana H. Wendl.) were transplanted into containers filled with, by volume, 1) 100% compost; 2) 60% compost, 25% vermiculite, 15% perlite; 3) 30% compost, 30% sphagnum peat, 25% vermiculite, 15% perlite; 4) 0% compost, 60% sphagnum peat, 25% vermiculite, 15% perlite. Two compost products were evaluated: SW, a 1:1 by volume mixture of partially composted seaweed and partially composted yard trimmings and SYT, a 1:1 by weight mixture of biosolids compost and yard trimmings compost. There was no difference in angelonia shoot dry mass among the different percentages of SW compost but angelonia plants grown in 0 and 30% SYT had greater shoot dry mass than plants grown in 60 or 100% SYT. Shoot dry mass of shooting star plants increased as the percentage of SYT compost increased from 0 to 30 % and then decreased while shoot dry mass of plants grown in SW compost decreased as the percentage of compost increased. There was no difference in coreopsis shoot dry mass or scutellaria shoot dry mass between the two compost products and there also was no difference in shoot dry mass among the different percentages of either compost product.     

Growth of Salt Sensitive Bedding Plants in Media Amended with Composted Urban Waste

Growth of Impatiens wallerana Hook.f (impatiens) and Antirrhinum majus L. (snapdragon) was evaluated in media containing 0, 30, 60, or 100 percent compost made from biosolids and yard trimmings. Shoot dry mass, size, and height of both impatiens and snapdragon linearly increased as the percentage of compost in the medium increased. Initial media soluble salt, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentrations also linearly increased as the percentage of compost in the medium increased. However, final shoot N, P, K, Ca, and Mg concentrations in both impatiens and snapdragon plants were not different among the media examined. Results suggest that impatiens and snapdragons can be successfully grown in 100 percent compost made from biosolids and yard trimmings.