As Alan Chadwick says, fertility is a marriage of the elements. "
The marriage of the four elements are combined in this matter, and cannot be separated."
Fertility as such is a chymical wedding of polarities, from which greater abundance emerges. When we tend the earth, we are really officiating an analogous marriage of Heaven and Earth from which their children the plants arise. This is a hierogamy, a divine marriage, between heaven and earth.
If we didn't have the perfect combination -- the perfect marriage -- of the elements, life as we know it would not exist. If things were just a bit dryer, or wetter, or colder, or hotter, everything would be different. If things were only slightly less balanced here, we would be like Venus or Mars, desolate landscapes. Likewise, on the farm, we are orchestrators of the elements. The gardener is always adding water when it's too dry, adding enlivening organic matter when the soil is to deadened, providing shade when it's too sunny, etc. If you weren't already doing all this, biodynamics wouldn't make much sense. But this is where we must remember that biodynamics is not about replacing anything but rather supplementing whatever works with enlivening practices such as the biodynamic preparations. Even Steiner says in the Agriculture Course that it is virtually "inconceivable" to consider farming these days -- in 1924 -- without a tractor. He was not recommending a return to draft power or doing away with technology but rather making sure that technology must serve LIFE.
With the introduction of tractors, we quickly produced the Dust Bowl in the USA due to irresponsible investments driving irresponsible farming practices. Only after the Dust Bowl was "conservation" tillage introduced on a large scale. We humans learn from our mistakes, perhaps slowly, but we do gradually learn.
The key to biodynamics may be found in this: “The proof that we are regenerated,” as Saint-Martin said, “is that we regenerate everything around us.”