Open air market, Campo dei Fiore, Rome
It's not just because soils were deeper and thicker... which was most certainly the case. It had a lot to do with the microbe populations. When we examine the scant remnants of our soil heritage, we discover that they had a diversity we can only dream of in most places today.
I make this point because we're generally unaware of what we're losing. The damage we're doing to the microbe infrastructure of the planet is appalling, and no one ever talks about it. What we're headed for, however, is a steady degradation of quality in the critical underpinnings of the soils we depend on for agriculture.
Science... and governments... ought to be devoting major resources to studying this problem, but very little is being done. It comes down, once again, to the problem that people won't spend time or money on trying to understand the unseen aspects of our environment—even though they turn out to be some of the most important parts of what is taking place around us. A collapse of our microbial infrastructure—both that of the soils and that of the oceans, where plankton are the ground floor of the entire food chain—would spell absolute disaster. We don't know enough about it to know how to fix it if it breaks; and evidence suggests that collapses of this kind may have taken place for natural reasons in the past, with what amounted to catastrophic results for the macrobiotic species.
A long term study needs to be undertaken to analyze the wild relatives of our most important crops and the symbiotic bacteria and fungi they grow in conjunction with. It may well be that we can vitally enhance crop health, productivity and viability by better understanding the microbial relationships that support them.
Soil conservation is no casual thing. Yes, it's true we recognize the need to preserve soils now—and it's come to us very late in the game. Even in the US, where we have deep insight into this question (prompted, in part, by the self-inflicted disaster of the dust bowl) we have a spotty record right up to the present moment. Farmers may have learned to preserve soils, but real estate developers certainly haven't; and countless thousands, probably millions, of acres of some of the best farmlands in the United States have, over the last five decades, been completely destroyed in order to make room for shopping malls and suburban developments.
It takes thousands of years to build a good soil column. It takes a few days for a bulldozer to destroy it. The action is criminal; yet we call it progress. And in foreign countries the pressures of development are ruining soils much, much faster than they are in the United States.