Biodynamic agriculture, a method of organic farming that has its basis in a spiritual world-view (anthroposophy, first propounded by Rudolf Steiner), treats farms as unified and individual organisms, emphasizing balancing the holistic development and interrelationship of the soil, plants, animals as a closed, self-nourishing system. Regarded by some proponents as the first modern ecological farming system, biodynamic farming includes organic agriculture's emphasis on manures and composts and exclusion of the use of artificial chemicals on soil and plants. Methods unique to the biodynamic approach include the use of fermented herbal and mineral preparations as compost additives and field sprays and the use of an astronomical sowing and planting calendar.

The development of biodynamic agriculture began in 1924 with a series of eight lectures on agriculture given by Rudolf Steiner at Schloss Koberwitz in what was then Silesia, Germany. The course was held in response to a request by farmers who noticed degraded soil conditions and a deterioration in the health and quality of crops and livestock resulting from the use of chemical fertilizers.[5] An agricultural research group was subsequently formed to test the effects of biodynamic methods on the life and health of soil, plants and animals. In the United States, the Biodymanic Farming and Gardening Association was founded in 1938 as a New York state corporation.

In Australia the first biodynamic preparations were made by Ernesto Genoni in Melbourne in 1927 and by Bob Williams in Sydney in 1939. Since the 1950s research work has continued at the Biodynamic Research Institute (BDRI) in Powelltown, near Melbourne Australia under the direction of Alexei Podolinsky. In 1989 Biodynamic Agriculture Australia was established, as a not for profit association. It has well over 1100 members and has local and regional groups throughout Australia. It publishes the biodynamic journal News Leaf quarterly and is the largest organic growers association in Australia.

Today biodynamics is practiced in more than 50 countries worldwide. The University of Kassel has a dedicated Department of Biodynamic Agriculture.

Studies of efficacy

Studies have compared biodynamic farming methods to both other organic methods and to conventional methods. Yields and soil quality have generally been found to differ little from those of other methods of organic farming, significantly from conventional farming methods.

• A study of the effect of biodynamic preparations on compost found that biodynamically treated compost contained 65% more nitrate than untreated compost, as well as significant differences in microbial life, composting temperature, carbon-dioxide respiration.

• A 1993 study compared soil quality and financial performance of Biodynamic and conventional farms in New Zealand. The study reported that, "The Biodynamic farms proved in most enterprises to have soils of higher biological and physical quality: significantly greater in organic matter, content and microbial activity, more earthworms, better soil structure, lower bulk density, easier penetrability, and thicker topsoil." The biodynamic farms were just as financially viable on a per hectare basis. The study compared biodynamic farms with adjacent conventional farms, but didn't attempt to compare farms of similar size, or with similar crops.

• A further study investigated whether biodynamic preparations had any effect on the yield and growth of lentil and wheat crops, weed populations and soil fertility in the short term. The study found that "[i]n general, soils and crops treated with biodynamic preparations showed few differences from those not treated". Plots tended with biodynamically treated compost produced results for yield, crop quality and soil fertility that were similar to those tended with non-biodynamic composts and NPK fertilizers. Some alteration was observed in the nitrogenous chemistry of the soil and grain where biodynamic field sprays were applied, however the study did not ascribe or discern any biological significance to the difference. Among the variables considered by the study, some measured outcomes correlated with biodynamic field spray usage, including a higher per-unit biomass yield ratio for lentils and a lowering of carbon and crude protein contents in wheat grains. The study's conclusion remarked that "any additional short-term benefits from biodynamic preparations remain questionable."

• A long-term study conducted at a commercial vineyard in California compared vineyard blocks treated with biodynamic preparations alongside those tended with general organic farming methods, to examine effects upon soil and crop quality. "No differences were found in soil quality" during the first six years of the study, and analyses of other indicators including the yield per vine, clusters per vine, cluster and berry weight also showed there were no differences. The study did find a statistically significant (p-value < 0.05) difference in the yield-to-pruning weight ratio, indicating an "ideal vine balance for producing high-quality winegrapes" for the biodynamically treated crop, but noted the control vines had been "slightly overcropped". In one particular year of the study the biodynamically treated winegrapes had significantly higher brix and notably higher total phenols and anthocyanins. In conclusion, the study found that biodynamic preparations "may affect" the vine canopy and chemistry, but showed no effects on the soil and tissue nutrient parameters measured in the study.

• A 21-year study by the FiBL Institute in Switzerland compared the agronomic and ecological performance of biodynamic, organic and two conventional systems. The study found that nutrient input in the biodynamic and organic systems was 34 to 51% lower than in the conventional systems but crop yield was only 20% lower on average, indicating more efficient production. The total energy (for fuel, production of mineral fertilizer and pesticides, etc.) to produce a dry-matter unit of crop was 20 to 56% lower for the biodynamic and organic systems, and pesticide input was reduced by 97% (by 100% for the biodynamic system). In regards to soil aggregate stability, soil pH, humus formation, soil calcium, microbial biomass, and faunal biomass (earthworms and arthropods), the biodynamic system was superior even to the organic system, which in turn had superior results over the conventional systems. With the significant increase in microbial diversity in the biodynamic and organic systems, there was a significant associated decrease in metabolic quotient, indicating a greater ability to use organic material for plant growth.