(Concepts from the book Biomimicry).
With the documentary Dirt: The Movie coming out, it seems relevant to throw around some topsoil ideas. Well, at least to me anyway. Humans started farming 10,000 years ago, and over that time we've co-evolved with our crops, to where they are now mostly dependent on us for their survival, and us on them. Over that time and especially in the last 100 years, we've inadvertently made them weak by using pesticides, we've isolated them from other biodiversity, and stripped the topsoil of most of its nutrients, replacing them with fertilizer.
I was surprised to learn that topsoil is not a renewable resource (in the relevant near-term). Once it is washed away or poisoned with pesticides and herbicides, it takes thousands of years to rebuild. Each time the soil is plowed, its complexity is diminished, and it is less rich. It also loses its ability to clump, which, in normal topsoil, allows water to run down to roots. Instead, farmed topsoil packs tight and cannot hold water. The ground dries and the topsoil blows away as dust. Since the rain can't go into the dirt, it pulls the soil with it to the streams and rivers. Worldwide, from 5 to 100 tons of topsoil per acre per year are lost.
Most topsoil on farms today is just a shadow of its former black, rich prairie or forest soil. Most of the fungi and microorganisms are gone. In many places we're already mixing into the layer of subsoil beneath the topsoil. So we add fertilizer, which runs off into our estuaries and poisons them. We attack insects and weeds with chemicals, something that worked in the short term but today insects and weeds are evolving around the chemicals. Each year a few survive, and those come back so that the more chemicals you use, the more chemicals you need to use. Since 1945, for example, pesticide use has gone up 3,300% to 2.2 billion pounds of pesticides each year - and crop loss from pests has increased 20% since then. So to boost production, we throw on 20 million tons of anhydrous ammonium fertilizer each year. All of this activity makes agriculture the number 1 polluting industry in the USA - doesn't that seem a bit odd? Growing food is the most damaging thing to our nation's land. Amazing, ain't it?