Session- Compost Utilization II
Performance of Various Composts and Compost Blends for the Production of Bedding Plants
BOUWKAMP, JOHN (1) and Catherine S. M. Ku (1)
Dept. NRSL, Univ. of Maryland, USA
We used compost from 16 sources, made from various feedstocks, and 10 two-way blends of four composts at two levels (33 and 50%) as bedding plant substrates. We grew four species of bedding plants (ageratum, marigold, petunia and vinca) in 804 flats for 30 days to a marketable stage. We harvested, dried and weighed both shoots and roots to estimate growth. We also determined the chemical (pH, electrical conductivity, C:N ratio and water soluble N and P) and physical (air filled porosity, water holding capacity and container capacity). The chemical and physical properties of the composts was used to predict the success of the resulting substrates as measured by plant growth. Producers and users can use this information in order to formulate successful substrates. It was also noted that the two-compost blends were usually superior in performance to either component separately. This can be explained, in part, by the chemical and physical properties of the blends.
Potential of Using Composts in Tropical Ornamental Foliage Plant Production and Utilization
Jianjun Chen (1), Dennis B. McConnell (2), Russell D. Caldwell (1), and Yingfeng Huang (1)
University of Florida, IFAS, (1) Mid-Florida Research and Education Center and (2) Environmental Horticulture Department, USA
Florida leads the nation in the production of tropical ornamental foliage plants. Millions of tons of potting media have to be used each year for foliage plant production. Florida is a major generator of municipal solid waste (MSW), biosolids (BS), and yard trimmings (YT) in the nation. Most of these waste materials are biodegradable and thus could be composted. This study was undertaken to exploit the potential of using composts as potting media components in foliage plant production and utilization. Representative composts were obtained from three Florida compost facilities. After determining physical and chemical properties, including metal speciation and leachability, the composts, each in percent combinations by volume, were mixed with peat and bark to formulate 12 potting media. The media were used for foliage plant production, seed germination, and rooting cuttings. Marketable foliage plants produced using the compost-formulated media were moved to an interior evaluation site to determine the suitability of compost-formulated media as growth substrates under interior conditions. Results indicated that five of the 12 compost-formulated media were comparable or superior to a control medium in rooting cuttings, germinating seeds, producing marketable plants, or interiorscape use. This study indicates that composts, after being appropriately mixed with peat and bark, can be used as potting media in every phase of tropical foliage plant production and utilization.
Biosolid and Compost Evaluation as Rooting Substrate in a Crop in Bogota
Eugenio GERALDO (1), Edna L Delgado (1)
(1) Environmental Engineering Research Center, University of Los Andes, Colombia
This project establishes potential uses of biosolids for the agricultural sector in Colombia. The biosolids analyzed come from the El Salitre plant, which is the first wastewater treatment plant in the city of Bogota, Colombia. Three materials were evaluated for use as a rooting substrate in flower crops (Christantemus). The first material was biosolid from the E1 Salitre treatment plant. The second material was composted biosolids from the El Salitre plant. The third material was composted primary sludge from a pilot plant. Composts were obtained from an aerated static pile system. All materials were classified as Class B with respect to the EPA pathogen reduction and as exceptional quality in terms of chemical contaminants. The capacity of the materials analyzed for use as a rooting substrate was compared to the standard material used (burned rice hulls alone or mixture with river sand or coal cinder). This analysis was done using the materials alone and using different mixture proportions of each material with the standard substrate. The mixtures evaluated were 0, 10, 15, 20 and 25 percent in volume for the biosolids. For the compost, the ratios were 0, 25, 50, 75 and 100 percent in volume. The experimental design consisted of complete blocks at random generalized. The statistical variables analyzed were the rooting percentage and the root dry weight, and the statistical analysis was made with the method of analysis of variance. Results show that for the biosolids mixed at low proportions (10 and 15 percent v/v), rooting was enhanced but required additional reduction of pathogens, odor control and homogenization of the mixture before use. Composts from primary sludge can be used as a rooting medium in different proportions without decreasing the rooting percentage. Biosolids composted over a period of four months were successfully used as a rooting substrate both with and without mixing with the standard material. However, composts subjected to deficient aeration and short maturation periods (two months) resulted in decreased rooting as the proportion of compost incresed.
Impacts of mulches on soil organic matter, microbial activity, nutrient availability, plant growth and plant pests
DANIEL A HERMS (1), John E Lloyd (1), Benjamin R Stinner (1,2), and Harry A J Hoitink (3)
(1) Department of Entomology, (2) Agroecosystem Management Program, and (3) Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, USA
We investigated effects of mulching with composted yard waste and recycled ground wood pallets on soil organic matter, microbial activity, nitrogen cycling, and plant health in ornamental landscapes. Both mulches increased soil organic matter and microbial biomass, but effects of composted yard waste were more substantial. Effects on nitrogen cycling and plant growth, however, were dependent on the C:N ratio of the mulch. As microbes decomposed low C:N (17:1) composted yard waste, high rates of mineralization increased nitrogen availability, which increased the growth and flower production of ornamental trees and shrubs. Conversely, mulching with high C:N wood pallets (120:1) decreased soil fertility and plant growth as microbes immobilized a high proportion of available nitrogen and phosphorus. Fertilization of plots mulched with ground wood relaxed this competition between plants and microbes for nutrients and increased the growth of both. Fertilization of plots mulched with composted yard waste had no effect on plant growth, indicating that decomposing compost fully met the nutritional requirements of both microbes and plants. Both mulches impacted the incidence of pest problems. Mulching with composted yard waste substantially decreased the incidence of root rot disease and mortality of rhododendron, which was increased by mulching with wood pallets. Trees mulched with composted yard waste were less resistant to leaf-feeding insects, but still grew faster in spite of experiencing more defoliation, suggesting that compost increased their ability to tolerate insect damage. This research demonstrates that mulching with composted yard waste can improve soil quality and enhance plant health in ornamental landscapes, thereby decreasing the need for pesticides and fertilizers in urban environments while diverting a valuable natural resource from landfills.