Growth of golden shrimp plant (Pachystachys lutea Nees.) transplants was evaluated in media containing 0%, 25%, 50%, 75%, or 100% compost derived from biosolids and yard trimmings. A commercial coir- or peat-based media was amended with compost. As compost composition in the peat or coir-based media increased from 0% to 100%, carbon/nitrogen ratios decreased; and media stability, nitrogen mobilization, pH, and electrical conductivity increased. Bulk density, particle density, air-filled porosity, container capacity, and total porosity increased as more compost was added to either peat- or coir-based media. Plants grown in media with high volumes of compost (75% or 100%) had less leaf area and lower shoot and root dry weight compared to the controls (no compost). Regardless of percentage of compost composition in either peat or coir-based media, all plants were considered marketable after 8 weeks.
S.B. Wilson, P.J. Stoffella, and D.A. Graetz
Kimberly A. Klock-Moore and George E. Fitzpatrick
Analytical determination and confirmation of minimum compost processing times and minimum curing times can aid commercial growers in selecting compost materials that should give them more reliable and consistent results in their operations. Five-cubic-yard volumes of yard-trimmings were assembled into three 1.25-cubic-yard compost piles at 60-day intervals. At the conclusion of the experiment, there were three piles each of compost of the following ages: 10 months, 8 months, 6 months, and 2 months. Compost was collected from each pile and screened through a 0.75-inch screen. Bulk density, water-holding capacity, air-filled porosity, carbon to nitrogen ratio, electrical conductivity, and ATPase activity were determined on samples from each reference compost pile. A bioassay using beans also was performed. These data will be presented.
Monica Ozores-Hampton and Thomas A. Obreza
In 1997, 24.7 million t of solid waste were produced in Florida (about 4.3 kg per person per day). If all biodegradable material was composted, 12.4 million t of compost would be produced annually. If this compost was used as a soil amendment in fruit and vegetable production, knowledge of its N mineralization rate would be important to determine the application rate. We measured the field N mineralization of four commercial Florida composts mixed with sandy soil (dry weight rate): Jacksonville (yard trimming compost, 127 t•ha-1), Sumter (municipal solid waste compost, 67 t•ha-1), and Nocatee and Palm Beach (yard trimming and biosolids composts, 63 and 56 t•ha-1). The control treatment was unamended soil. Open-top, 20-cm long PVC columns were filled with soil/compost mixtures and fitted at the bottom with a trap containing cation and anion exchange resin to capture leaching NO3 and NH4-N. The columns were buried in the soil at ground level and incubated in situ for 45 and 90 days in the spring. The resin was extracted with 1 N KCl and the mass of NO3-N and NH4-N adsorbed was determined. A similar procedure measured the NO3-N and NH4-N left in the soil/compost mixture. After 90 days in the field, net N immobilization was observed with Nocatee (-4.3%), Sumter (-3.0%), and Jacksonville (-1.3%) composts, while N mineralized (6.4%) from Palm Beach compost. Where N immobilization occurred, composts had initial C: N greater than 20: 1 and N concentration <1.6%. Mineralization occurred where compost had C: N ratio lower than 20: 1 and N concentration greater than 1.6%.
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.
Catherine S.M. Ku and John C. Bouwkamp
Production of `Top White', `Peterstar Pink', `Lilo Red', and `Red Success' poinsettias were evaluated in a treatment combinations that included 10 compost blends, three compost levels, and two commercial soilless substrates of Sunshine Mix 1 and Pro Gro 300S as controls. The compost feedstocks included PSG polymer dewatered biosolids (PSG), lime dewatered biosolids (CP), yard trimmings (YT), poultry litter (PL), and municipal solid waste (MSW Bedmininster). The PSG, PL, YT, and MSW were co-blended with CP on a 2:1 ratio (v/v), all other composts were co-blended on a 1:1 ratio (v/v). The compost levels of 33%, 50%, and 67% were mixed with peat:perlite (1:1, v/v). There were five replicates per treatment. Plants were fertilized once weekly with 200 mg·L–1 N from 21N–2.2P–16.6K. Sunshine mix produced control plants that had greater canopy diameter and plant grade than Pro Gro mix. Plant height was reduced as compost level increased from 33% to 67%. Blends of PSG:PL at the 33% and 50% levels and PSG:YT at the 33% level produced premium-quality plants. Good-quality plants, similar to those grown in Sunshine Mix, were produced with the PSG or PL compost blended with immature MSW at the 33% level; PSG:PL blend at a 67% level; PSG:YT blend at the 50% and 67% levels; and PL:YT blend at the 33% level.
The objective of this experiment was to compare the growth of impatiens `Accent Orange' in substrates containing compost made from biosolids and yard trimmings with four slow-release fertilizer application rates. Plugs of impatiens were transplanted into 400-ml pots filled with 100% compost as a stand-alone substrate or with 60%, 30%, or 0% compost combined with control substrate components. Six days after transplanting, all plants were top-dressed with 0.5, 1, 2, or 4 g of Nutricote 13N-5.7P-10.8K (type 180) per pot. Shoot dry mass increased as the percentage of compost in the substrate increased from 0% to 100%. Shoot dry mass also increased as the fertilizer application rate increased from 0.5 to 4 g per pot. Plants grown in 30% and 60% compost with 0.5 g of fertilizer were similar in size to plants grown in 0% compost with 4 g of fertilizer per pot. Plants grown in 100% compost at all of the fertilizer rates were larger than all other plants in this study.
Nancy E. Roe, Peter J. Stoffella, and Donald Graetz
The composition of composts derived from municipal solid wastes can affect emergence and seedling growth. Composts consisting of biosolids and yard trimmings [standard compost (SC)] alone or with mixed waste paper (MWP), refuse-derived fuel (RDF), or refuse-derived fuel residuals (RDFR) were evaluated in seedling trays and pots for vegetable crop seedling emergence and growth. In trays, tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), and pepper (Capsicum annuum L.) seedlings emerged faster from a commercial peat-lite mix and from sandy field soil than from the composts. Plants were tallest and shoots were generally heaviest in the peat-lite mix and aged SC and smallest in the field soil. MWP compost generally inhibited early seedling growth more than RDF or RDFR composts. Among the composts, seedlings were tallest and heaviest in SC. In pots, growth of each vegetable was generally greatest in SC, followed by other composts, and lowest in sandy soil. Tomato and pepper seedling emergence was more sensitive to the inhibitory effects of the RDF, RDFR, and MWP composts than cucumber seedling emergence. Fertilizer increased plant growth in each medium except SC, in which cucumber stem diameter was not increased. Adding MWP, RDF, or RDFR to SC generally decreased seedling emergence and growth. The composts prolonged days to emergence and decreased percent emerged seedlings. However, subsequent seedling growth in composts was equal to or greater than seedlings in the peat-lite mix and much greater than those in the sandy field soil.
Sandra B. Wilson and Peter J. Stoffella
Peat is used extensively in the nursery industry as a primary component in commercial “soilless” potting media. The increased use of peat as an organic amendment with superior water-holding capacity is challenged by economic and environmental pressures. Developing inexpensive and nutrient-rich organic media alternatives can potentially reduce fertilization rates, irrigation rates, and ultimately, nursery costs. In addition, controversy over the effects of peat mining has inspired a national search for peat substitutes. With our burgeoning population, it is logical to screen waste products as potential alternatives to peat. Growth of Pachystachys lutea Nees. (Golden Shrimp Plant) transplants was evaluated in media containing 0%, 25%, 50%, 75%, or 100% compost derived from biosolids and yard trimmings. Compost was amended with a commercial peat- or coir-based media. As compost composition in the peat or coir-based media increased from 0% to 100%, carbon/nitrogen (C/N) ratios decreased, and media stability, N mobilization, pH, and electrical conductivity (EC) increased. Bulk density, particle density, air-filled porosity, container capacity, and total porosity increased as more compost was added to either peat- or coir-based media. Plants grown in media with high volumes of compost (75 or 100%) had reduced leaf area and reduced shoot and root DW than the controls (no compost). Regardless of percentage of compost composition in either peat or coir-based media, all plants were considered marketable after 8 weeks.
Catherine S.M. Ku and John C. Bouwkamp
Blending compost from various feedstocks may increase the beneficial effects of compost as potting substrate. A factorial treatment combinations included 10 compost combinations, Sunshine Mix and Pro Gro 300S as controls, three compost levels, and three chrysanthemum cultivars. The compost combinations were Compro (CP), poultry litter (PL), PSG polymer dewatered biosolids (PSG), yard trimmings (YT), CP:PL, CP:PSG, CP:YT, PL:PSG, PL:YT, and PSG:YT; all blends were on a 1:1 ratio (v/v). The compost levels were 50%, 75%, 100%; and chrysanthemum cultivars included `Boaldi', `Cherry Davis', and `Yellow Favor'. All treatments were replicated six times. Plants were fertilized with 100 mg/L N from 20N–8.8P–16.6K twice weekly. All compost substrates, except PSG blends produced plants that were shorter than the controls. All compost blends produced similar or greater number of flower than the controls. Plants grown in substrates containing PSG and/or CP produced dark green or green foliages, and other substrates produced plants with pale green leaves. The PSG:PL and PSG: YT blends produced premium-quality plants. All other compost blends produced good-quality plants that were similar to the controls.
The success of long-term vegetable production and maintenance of environmental quality is dependent on soil quality. Indicators of soil quality include cation exchange capacity (CEC), organic matter (OM), carbon (C), pH, and the number and community structure of soil organisms. The use of appropriate compost has been shown to improve soil quality and enhance the response to fertilizer, therefore improving growth and yield of vegetable crops. The objective of this study was to evaluate changes in the chemical and biological properties of soil in response to compost use in conventional vegetables production systems. A survey was conducted on 5 farms (three in Immokalee, and one each in Delray Beach, and Clewiston) growing tomato, pepper, and specialty vegetables. Most of the farms were applying composted yard trimming waste alone or in combination with biosolids or horse manure at application rates of between 7 to 112 Mg·ha-1 once a year. Soil samples were taken from composted and non-composted areas in each farm during Feb. and Mar. 2002. Soil pH, OM, C, K, Ca, Mg, Cu, Fe, MN and Zn were higher in the composted areas compared with the non-composted areas for each farm. CEC values in composted areas were double those in non-composted areas. Most importantly, application of compost enhanced the overall soil microbial activity as determined by total microorganism number, SRD (species richness diversity), and TSRD (total species richness diversity) of six functional groups including heterotrophic aerobic bacteria, anaerobic bacteria, fungi, actinomycetes, pseudomonads, and nitrogen-fixing bacteria, in all the participating farms. The greatest soil quality improvement was seen in soils receiving the highest rates of compost for the longest time.