By Tom Mansell

We now come to some of the most famous and well-known preparations in biodynamics, the field sprays. Cow manure or silica fermented in the ground in cow horns is practically the very symbol of biodynamics. These preparations are highly representative of the movement, but what, if anything, do they do?

Field spray preparations

These preparations are diluted in water, "dynamized" (more on that later), and sprayed onto vines.

Dynamization

What is dynamization? From Steiner:

"You must, however, thoroughly combine the entire content of the horn with the water. That is to say, you must set to work and stir. Stir quickly, at the very edge of the pail, so that a crater is formed reaching very nearly to the bottom of the pail, and the entire contents are rapidly rotating. Then quickly reverse the direction, so that it now seethes round in the opposite direction. "Do this for an hour and you will get a thorough penetration. Think, how little work it involves! The burden of work will really not be very great. Moreover, I can well imagine that […] the otherwise idle members of a farming household will take pleasure in stirring the manure in this way. Get the sons and daughters of the house to do it and it will no doubt be wonderfully done.

Nowadays, some farmers have lots of spray to make and stirring by hand for an hour, in spite of Steiner's assertion, can be tedious. Thus we have seen the development of flowforms. Flowforms are large structures containing basins with geometries that allow water to swirl in oppposing vortices as Steiner suggests (seen at the beginning of the video below).

The theory behind this process is that it adds "energy" and oxygen to the water. What this "energy" is is ill-defined. From Nicolas Joly's book Wine from Sky to Earth: "Dynamization creates a profound intimacy between the solid and the subtle, between what one dynamizes and the water. The rhythm acts like an appeal." He then digresses into a discussion of artificial insemination of cows.

The addition of oxygen to the mixture, though, is real. Agitating the liquid will saturate it with oxygen, except this happens fairly quickly, not after an hour. The reason for this is that oxygen is not very soluble in water to begin with, only soluble at about 8 ppm, or 8 mg/L and it is even lower when the water is warmer. This low solubility is the reason we require the protein hemoglobin to transport oxygen in our blood, since the saturated level wouldn't be nearly enough to sustain our oxygen needs.

While it is possible that the fermented product could be consuming oxygen during this hour (fermenting wine, for example, would consume about 2 ppm of oxygen per minute), the small amounts of compost and/or silica added to the large amount of water make this unlikely.  Therefore, it is probably safe to conclude that dynamization of a preparation of 100L will add approximately 800 mg of oxygen, about half the oxygen contained in one breath of air.

Spraying Science

While preparations 500 (horn manure) and 501 (horn silica) have been found to contain high levels of cytokinins (plant stimulatory hormones), research done by Dr. Jennifer Reeve (as mentioned previously) showed that "The biodynamic field sprays (500, 501 and barrel compost) were not shown to have any effect on soil quality."  Thus, the mode of action, if any, of preparation 500 is likely similar to that of the compost preparations mentioned previously. 

For more information about compost preparations, see the previous post in this series.

Silica and Sunlight

Steiner's proposed mechanism for the effectiveness of preparation 501 is the intimate connection of silica to cosmic forces. Recent rationalizations of silica's effect on leaves include postulating that the silica crystals (ground quartz) focus and/or refract sunlight like a "prism", causing more sunlight to contribute to photosynthesis. 

The accompanying video has Mike Benziger of Benziger Vineyards giving his explanation of this phenomenon (around 1:18).

This is rather unlikely for several reasons. First, the silica is white and thus reflective, so some sunlight that could have fallen on the leaves is reflected back. Second, prisms do not magnify light or shift colors. When light is refracted through a prism, it is broken into its constituent wavelengths, not redshifted significantly. Third, even if the silica did "bend the sunlight more towards infrared", the maximum absorbance of chlorophyll occurs in the purple-blue range of visible light, with a minor peak in the red-orange area.

Essentially, the hypothesis that quartz crystals intensify the sunlight that reaches leaves is likely bunk.

Silica and Fungus

An interesting thing about silicon is that while it is mostly inert (in sand, glass, quartz, etc.), it can be converted into bioactive forms and used by organisms. One obvious example of this is diatoms, whose silica skeletons form diatomaceous earth (kieselguhr). Silicon is also taken up by plants and incorporated into stems or, in some cases, segregated to large silicous masses inside the plant. This is the case with horsetail (Equisetum), the dry weight of which can be up to 70% silica.

Indeed, spraying plants with bioactive forms of silica has been shown to help protect them against fungal disease. Most of this research has been done with rice, but there exists studies where spraying with potassium silicate decreased incidence of powdery mildew on grapevines. In a 1996 study in the American Journal of Enology and Viticulture, Reynolds et al. concluded that applying potassium silicate did reduce incidence of powdery mildew, but not as well as the fungicide Kumulus S (sulfur).

It's unlikely that silica is directly toxic to microbes, so what could the mechanism of this silica effect be? We might speculate that the spraying of silica onto plants via horsetail tea and/or preparation 501 might invoke some sort of resistance in the plant. The hypothesized mechanism is due to what is known as systemic acquired resistance. 

Essentially, since silicon naturally builds up at sites of plant injury and infection, it stimulates the production of the plant's natural defenses, antimicrobial compounds. Increased uptake of silica may trick the plant into thinking it is under attack, prompting the synthesis of these compounds so that when fungus does attack, the plant is at the ready.

It's possible, then that the silica, which enters a cow horn as inert quartz, could be converted by microorganisms into bioactive forms like silicates. In horsetail, much of the silica is already present in bioactive form.  If this is true, preparations 501 and 508 could indeed be providing some measure of fungus control in the vineyard, but it probably has nothing to do with crystals refracting sunlight or dynamization imbuing these mixtures with cosmic forces.

Further reading

R Steiner, Agriculture

N Joly, Wine from Sky to Earth: Growing and Appreciating Biodynamic Wine

AG Reynolds et al., "Use of potassium silicate for the control of powdery mildew [Uncinula necator (Schwein) Burrill] in Vitis vinifera L. cultivar bacchus", AJEV, 1996.

Fauteux et al., "Silicon and plant disease resistance against pathogenic fungi", FEMS Microbiology Letters, 2005