Organic and Biodynamic Management: Effects on Soil Biology
L. Carpenter-Boggs,* A. C. Kennedy, and J. P. Reganold
Biodynamic agriculture is a unique organic farming system that utilizes, in addition to the common tools of organic agriculture, specific fermented herbal preparations as compost additives and field sprays. The objective of this work was to determine whether biodynamic compost or field spray preparations affect the soil biological community in the short term, beyond the effects of organic management. Four fertilizer options: (i) composted dairy manure and bedding (organic fertilization), (ii) the same material composted with biodynamic compost preparations, (iii) mineral fertilizers, and (iv) no fertilizer were investigated with and without the biodynamic field spray preparations.
Both biodynamic and nonbiodynamic composts increased soil microbial biomass, respiration, dehydrogenase activity, soil C mineralized in 10 d (MinC), earthworm (Lumbricus terrestris ) population and biomass, and metabolic quotient of respiration per unit biomass (qCO2) by the second year of study. No significant differences were found between soils fertilized with biodynamic vs. nonbiodynamic compost. Use of biodynamic field sprays was associated with more MinC and minor differences in soil microbial fatty acid profiles in the first year of study. There were no other observed effects of the biodynamic preparations. Organically and biodynamically managed soils had similar microbial status and were more biotically active than soils that did not receive organic fertilization. Organic management enhanced soil biological activity, but additional use of the biodynamic preparations did not significantly affect the soil biotic parameters tested.