Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/1/1999
Publication Date: N/A
Citation: Carpenter-Boggs, L., Kennedy, A.C., and Reganold, J.P. Organic and biodynamic management: effects on soil biology. Soil Sci. Soc. Amer. J. 64:1651-1659. 2000. Interpretive Summary: The biodynamic preparations are fermented herbs and minerals, used in very small amounts as additions to compost and as field sprays on biodynamic farms. Although practitioners of biodynamic agriculture claim that the preparations benefit microbial activity and populations, little scientific research has addressed this claim. Effects of the biodynamic preparations on the soil microbial community were investigated in field trials. Four fertilizer options: biodynamic compost, nonbiodynamic compost, mineral fertilizers, and no fertilizer were tested with and without the biodynamic field sprays. Addition of either type of compost to soil resulted in greater microbial activity and populations. Whether or not the biodynamic compost preparations had been used in the compost had no effect on overall microbial activity of populations. The types of activity and populations, however, were affected by use of the biodynamic preparations. Generally, microbial populations inoculated onto a single carbon source substrate wil use increasingly more of the substrate over the course of an incubation. Microbes in soils that received biodynamic compost initially were less able to use some carbon substrates, although after further incubation this difference disappeared. Use of the biodynamic field sprays also affected the microbial population's use of some carbon substrates. The meaning of these effects is not clear, but they suggest that the biodynamic preparations affect soil microbial physiology. This research will impact scientists who study microbial inoculants and volatile chemical signals, farmers who use the biodynamic preparations, farmers who are considering using the preparations, and extension agents who may advise farmers on the use or disuse of the preparations.
Technical Abstract: Biodynamic preparations were investigated in field trials using a 4 x 2 factorial design of fertilizers and field sprays. Four fertilizer options: biodynamic compost, nonbiodynamic compost, mineral fertilizers, and no fertilizer were tested with and without the biodynamic field sprays. Compost treated with biodynamic preparations 502 through 507 and compost not treated with biodynamic preparations caused similar changes in soil microbial parameters as compared to mineral fertilized or unfertilized plots. Classical microbial parameters of soil quality were affected by presence, but not type, of compost. Composts increased soil microbial biomass, respiration, dehydrogenase activity, readily mineralized soil carbon, earthworm populations and biomass, and qCO2. Functional abilities of microbial communities in soils were affected by type of compost applied. Early utilization of potential carbon substrates was lower in soils receiving biodynamic compost than in soils receiving nonbiodynamic compost Use of biodynamic field sprays was correlated to higher readily mineralized soil carbon (RMC) and lower dehydrogenase activity per unit RMC in 1995. Biodynamic field sprays also altered the soil community's use of carbon substrates. Biodynamic preparations used in compost and as field sprays affected the soil microbial community.