Effects of biodynamic preparations on compost development

Biodynamic (BD) agriculture is an organic farming system that relies heavil y on compost as a fertilizer. Six herbal preparations are added to composti ng materials in order to make BD compost. Proponents claim these additions produce higher quality compost under farm conditions. In this study, BD com post preparations were applied to 3.5 t compost piles made of dairy manure and woodshaving bedding. Application of the BD preparations also requires 6 1 soil and 8 1 water; therefore control piles received the same additions of soil and water as BD compost piles, but no BD preparations. Biodynamic-t reated composts maintained an average 3.4 degrees C higher temperature thro ughout the eight-week active composting period, suggesting more thermophili c microbial activity and/or faster development of compost with BD treatment . Final samples were taken when active composting slowed and the piles ente red a ripening stage. At the final sampling, BD-treated piles respired CO2 at a 10% lower rate and had a larger ratio of dehydrogenase enzyme activity to CO2 production. Microbial communities in the finished BD and control pi les were differentiated by principal component analysis of microbial phosph olipid fatty acids. Final samples of BD-treated composts also had 65% more nitrate than control piles. Biodynamic preparations thus effected discernib le changes in compost chemical and microbial parameters.