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Compost Science & Utilization, (2009), Vol. 17, No. 1, 4

Materials and Methods

Nitrogen and Sulphur Transformations in Composts Containing Chicken Feathers
Investigators: Justyna Bohacz, Teresa Korniowicz-Kowalska
Chair of Agricultural Microbiology, Laboratory of Mycology, University of Life Sciences, Lublin, Poland
Objectives: Estimation of nitrogen and sulphur transformations, with special emphasis on forms available to plants, in composts containing keratin wastes (chicken feathers). Chicken feathers

composted with pine bark and rye straw are subject to intensive mineralisation and biotransformation with efflux of water-soluble components: N-NH4, N-NO3 and S-SO4. The content of N-NH4, N-NO3 and S-SO4 in water extracts of the studied composts was positively correlated with the time of composting. The release of those components reached a maximum after 15 weeks of composting of feather wastes. The highest amounts of soluble forms of nitrogen and sulphur were recorded in composts enriched with straw, especially those with C/N=25, and the lowest in composts without straw, with C/N=25. It was also demonstrated that changes in the concentration of N-NH4 were correlated with increase in the concentration of N-NO3 and S-SO4 in water extracts of the composts. Increase in the content of N-NO3 and S-SO4 in extracts from the compost mass, with simultaneous decrease in the level of soluble N-NH4, may be used as a reliable indicator in the estimation of the maturity of composts containing waste feathers.

Vermicompost as a Potting Amendment to Improve Growth and Flowering of Two Commercially Grown Ornamental Species
Investigators: Cristina Lazcano, Departamento de Ecología y Biología Animal., Facultad de Ciencias, Universidad de Vigo, Vigo, Spain; Jorge Domínguez, Departamento de Ecología y Biología Animal, Universidad de Vigo, Vigo, Spain
Objectives: To evaluate the feasibility of incorporating vermicompost as a plant growth and flowering promoter into a commercial ornamental production system. Pansies and Primulas were grown in peat-based conventional greenhouse medium substituted with 5%, 15% and 25% (v/v) commercial and pig slurry vermicompost. In order to observe plant growth-promoting effects independent of nutrient supply and pathogen control, both plants were supplied with recommended inorganic fertilization and chemical fumigation for pathogen control. Vegetative growth and flowering were evaluated and compared to plants grown with no vermicompost addition. A general reduction of growth was observed in both species with increasing concentrations of commercial and pig slurry vermicompost. The highest percentage of vermicompost (25%) showed 20% of plant mortality, high levels of stress and damage to the photosynthetic apparatus, as well as a significant reduction in the number and biomass of leaves and in flower production. Most likely, the increase in electrical conductivity, and pH and the decrease in air space produced after the application of vermicompost interacted synergistically and were magnified under sub-irrigation, causing the observed effects on plant growth. Therefore the cultivation system must be taken into account when incorporating vermicompost as a plant growth promoter in commercial conditions.

Compost-Based Nursery Substrates: Effect of Peat Substitution on Organic Melon Seedlings
Investigators: F. Tittarelli, E. Rea, S. Canali, A. Trinchera, C.M. Rivera, Agricultural Research Council - Research Centre of soil-plant system (CRA-RPS) Rome, Italy; V. Verrastro, F. Ceglie, Mediterranean Agronomic Institute (CIHEAM-IAMB), Bari, Italy; J.A. Pascual, Department of Soil Water Conservation and Waste Management, Centro de Edafologia y Biologia Aplicada del Segura (CEBAS-CSIC), Murcia, Spain
Objectives: To test a bovine manure compost and a green compost, as a partial peat substitute in growing media formulated for organic melon transplant production. In particular, to accomplish this objective, composting parameters were monitored during the whole process to guarantee the necessary uniformity of the final products’ characteristics for their utilisation as quality organic components of substrates. The performances of the compost-based growing media were evaluated in two greenhouse experiments in which melon seedlings for organic farming were grown. Treatments, differentiated on the basis of the volume percentage of the two analysed composts, were compared to the control (a mixture of peat, coconut fibre and perlite). In order to respect the guidelines of organic production, all the treatments were fertilised, at the beginning of the trial, with guano. Compost-based substrates were analysed for physical, physico-chemical and chemical parameters (bulk density, porosity, pH, EC, nutrients content etc.). Even though significant differences were observed, recorded values were in the range of acceptability for growing media. In terms of performance, seedling growth in treatments containing 30% and 50% of composts was significantly higher than in control.