The first possibility of breaking through the hardened layer of current orthodox opinion came through discoveries that cluster around the concept of the so-called trace elements. Dr. Steiner had pointed out as early as 1924 the existence of these finely dispersed material elements in the atmosphere and elsewhere, and had stressed the importance of their contribution to healthy plant development. But it still remained an open question whether they were absorbed from the soil by roots or from the atmosphere by leaves and other plant organs. In the early thirties, spectrum analysis showed that almost all the trace elements are present in the atmosphere in a proportion of 10-6 to 10-9. The fact that trace-elements can be absorbed from the air was established in experiments with Tillandsia usneodis. It is now common practice in California and Florida to supply zinc and other trace elements, not via the roots, but by spraying the foliage, since leaves absorb these trace elements even more efficiently. (Steiner 2007:7)
It was found that one-sided mineral fertilising lowers the trace-element content of soil and plants, and — most significantly — that to supply traceelements by no means assures their absorption by plants. The presence (or absence) of zinc in a dilution of 1:100 million decides absolutely whether an orange tree will bear healthy fruit. But in the period from 1924-1930 the bio-dynamic preparations were ridiculed “because plants cannot possibly be influenced by high dilutions.” (Steiner 2007:7)
Zinc is singled out for mention here not only because treatment with very high dilutions of this trace element is especially essential for both the health and the yield of many plants, but also because it is an element particularly abundant in mushrooms. A comment by Rudolf Steiner indicates an interesting connection which can be fully understood only in the light of the most recent research. We read in the Agricultural Course: “… Harmful parasites always consort with growths of the mushroom type, … causing certain plant diseases and doing other still worse forms of damage. … One should see to it that meadows are infested with fungi. Then one can have the interesting experience of finding that where there is even a small mushroom-infested meadow near a farm, the fungi, owing to their kinship with the bacteria and other parasites, keep them away from the farm. It is often possible, by infesting meadows in this way, to keep off all sorts of pests.” (Steiner 2007:7)
STEINER, Rudolf. 2007. The Agriculture Course. (Trans.: George Adams) Shrewsbury: Wilding & Son Ltd.