The energy content of food produced for residents of the United States has risen from 3200 calories per person per day in the 1970s to almost 4000 today (1), approaching double the average daily requirement. Much of that is wasted. For many such reasons, shrinking the economic "throughput" of agriculture and associated industries can be a much more straightforward process than in other areas of human society, and it need not mean that anyone go undernourished.
The purpose of growing crops and pasture is to convert solar energy into food and other useful products. But as it is currently organized, US agriculture and the businesses it feeds absorb more energy in the form of fossil fuels and other resources than they capture from the sun. Reducing through-put would not only save energy, it could pay a host of other ecological dividends. That's because as it stands, agriculture is the planet's chief cause of soil erosion (2), biodiversity loss (3), and creation of coastal hypoxic areas, or "dead zones" (4).
Efforts to bring agriculture into line with ecological reality fall into two classes. Some efforts can be started today and will help get humanity through mid-century. Others (which also must be accelerated, and soon) will take longer to complete but will be necessary to sustain agriculture to the end of the century and beyond.
In the short run: go to the roots of the economy
The roots of every economy are largely in agriculture; ultimately, all economic activity depends on energy from the farm, the mine, or the well . But farming differs qualitatively from industrial work in that it is tied closely to seasonal cycles and uncontrollable environmental fluctuations. That clearly isn't the ideal pattern for efficient capital accumulation, so the past century has seen relentless efforts to mold agriculture into the factory model as closely as possible.
But because of its dependence on natural cycles, the "factory farming" ideal can be realized in only the crudest ways. So a growing range of more easily regimented industries has been grafted onto an agricultural rootstock. Although we call American agriculture a "food system," it generates food only as a by-product; the primary product is wealth to support companies that produce seed, machinery, fertilizer, pesticides, diesel fuel, and other inputs, and others that feed on the food leaving the farm. That leaves a lot of high-energy fat that could be cut.
The table below, based on figures from the government's Bureau of Economic Analysis, shows that agriculture's contribution to the GDP, measured in real, inflation-adjusted dollars, has grown significantly over the past quarter-century but that the real action has been in industries that depend on the output from agriculture. The processing of raw agricultural products into food--what the government classifies as food "manufacturing"--has grown twice as fast as agriculture, and food service has grown almost four times as fast, much of that growth attributable to Americans' increasing tendency to eat out. Compared with farming, which is bound to seasonal rhythms and natural processes, food processing and service are highly adaptable to organization along industrial lines. That brings greater capacity for economic growth.
Meanwhile, the value of food marketing--including packaging, labor, transportation, energy, advertising, profit, and other items--has risen even faster, reaching four times the value of the food produced on farms. Reductions that...