Evaluating Quality and Suppressiveness Of Austrian Biowaste Composts

Abstract

Twenty-one composts from source separated household biowaste plus other organic materials were evaluated for their biomaturity. The major part of the samples proved to be mature and enhancing plant development in a plant growth assay with cress. In addition to the standard physical and chemical parameters, water soluble C/N, humic/fulvic acid ratio, ratio of optical absorbances at 400 nm (E₄) and 600 nm (E₆) and cation exchange capacity were determined. None of these parameters was correlated with plant growth. Thus neither was suitable as an indicator to predict biomaturity in terms of growth enhancement and lack of phytotoxicity. The results of a germination test with compost extract were well correlated with the results of the plant growth test. Composts were suppressive to Pythium damping-off. The extent of suppressiveness was connected with the composts' content of organic matter.