At present, 80 percent of our farmable acreage is planted in annual crops, only 20 percent having the beneficent coverage of perennials. This, by the standard of any healthy ecosystem, is absurdly disproportionate. Annual plants are nature's emergency medical service, seeded in sounds and scars to hold the land until the perennial cover is re-established. By this rule, our present agriculture, which gives 80 percent of our farmland to annuals, is in a state of emergency.

You can't run a landscape, any more than you can run your life, indefinitely in a state of emergency. To live your life, to live in your place, you have got to bring about a settlement that does not involve you continuously in worry, loss, and grief. And so "A 50-Year Farm Bill" proposes a 50-year schedule by which the present ratio of 80 percent annual to 20 percent perennial would be exactly reversed. The ratio then would be 20 percent annual to 80 percent perennial. And perhaps I need to say plainly here that the perennial crops would be forages and grains. Nobody at present is talking about the possibility of breeding and raising perennial table vegetables, though they should.

By reversing this ratio, reducing annual plowing by four-fifths, and making it possible to plow in any year only the least vulnerable land, soil erosion would be radically reduced. So would chemical pollution, because perennials grown in mixtures such as grasses with legumes, as they are in most pastures and many hayfields, are more self-sustaining and less chemical-dependent than annual monocultures.
Link
Interesting article published in The Atlantic which discusses the perils of monoculture and how factory farming plays a role in soil depletion (and thus decreased nutrition in the food we eat).