The Unnaturalness of Agriculture
I recently brought a cake to a friend's party, and several people asked me if I had made it from scratch, which I had. In an age dominated by manufactured, pre-prepared foods, the ability to make a cake from raw ingredients seems to inspire awe in some folks.
Back when I farmed, the ability to grow food from scratch -- just seeds, soil and tools -- earned me similar admiration. I appreciated this then, but now that I do agricultural research, growing food from scratch seems more than a little troubling.
Let me explain.
Nature rarely mixes interdependent plants and animals from scratch. Instead, the Earth is carpeted with complex communities of organisms that don't change much over time. These communities are stable, partly because they're built around perennial plants: trees, shrubs and grasses that live for many years.
Perennials typically have deep roots. Both the roots and the aboveground parts are present year-round, keeping wind and water from carrying soil away. Perennials also can capture more -- and waste less -- water and nutrients.
Unlike most of nature, our food depends largely on annual plants, which grow, make seeds and die in one year. The typically large and numerous seeds of annuals like rice, wheat, corn and beans are what we eat to provide most of our calories. This almost certainly was an important reason our ancestors worked at learning how to grow annuals. These plants also must have attracted attention because the extra energy in their large seeds gives them a head start in growth over smaller-seeded perennials, especially -- as early farmers discovered -- if the starting line is bare soil.
But in the wild, bare soil is rare. This means that if we want to grow particular annuals, we have to get out there and clear lots of ground, and we have to do it every year. The huge, recurring expanses of bare earth that result are something I call "unnatural disturbances."
To be fair, there are natural forces that leave soil bare. But even what we call natural disasters change things on a tiny scale compared with growing annual crops. The eruption of Mount Saint Helens in 1980, one of the largest recent natural disturbances, buried 6 square miles outright and dusted ash over another 22,000. But American farmers clear 500,000 square miles with machines and chemicals every year.
What's so bad about bare soil? A quick recipe for soil erosion would say, "Expose soil, then wait for wind or rain." In the upper Midwest, we follow that recipe to the letter not only every spring at planting time, but also from October through May, when the annuals are all dead and gone. Even during the growing season, annuals shield too little of the soil with their leaves and hold too little of it with their roots. This means that any significant amount of rain washes soil from every field. This soil is irreplaceable, and our supply of the stuff is running out.
We don't rely on them nearly as much as we could, but there are time-tested ways to get more of the food we need without relying so much on annual plants. One would be to grow more alfalfa, grass and other deep-rooted perennials that we can't eat but which animals like cows, sheep and goats make into meat and milk. We also could shift annual cropland to fruit and nut trees.
Another option would be to coax perennial plants into making more, larger seeds than they do in the wild. This way we can continue our reliance on grains but without the faults of annuals. Plant breeders are progressing toward this, but achieving competitive yields with perennials will take decades. Such sustained effort will require big commitments from government and the private sector.
However we end up "perennializing" our agriculture, one thing is clear: While cooking from scratch may be great, growing food that way is not.