Characterization of several on-farm and industrial composted materials

Manure management and composting methods may greatly affect compost charact eristics. An experiment was conducted to characterize 23 on-farm and 6 indu strial composts in Quebec (Canada). Cluster analysis identified two major g roups characterized by their chemical composition, source materials, manage ment intensity and degree of decomposition. Electrical conductivity, total N and K, water-soluble NH4+, PO4, K, Al and organic C, and a cress test wer e the best chemical and biological parameters for grouping composts. These groups were strongly associated with bedding rate, turning frequency, compo sting duration, profile windrow appearance, material aggregation and odor. When restricted to dairy manure composts, no clear relationship could be es tablished by cluster analysis between material grouping and their farm mana gement. Statistical analysis on single chemical parameters of dairy manure composts, however, identified five farm management factors: type and amount of bedding, system of manure handling and storage, compost windrow turning , composting length and milk production intensity. These factors affected o ne or several major parameters: pH, dry matter, electrical conductivity, to tal and water-soluble C, N, P and K, and humic components characteristics. This study demonstrated the importance of leaching losses in the on-farm co mposting operations in humid cold regions and the need for more environment ally sustainable composting methods.