There’s still much I don’t understand about our farm policy, but let me start by telling you what I do know about the federal Farm Bill.

What I do know is that this obscure piece of legislation that comes along every five years or so largely sets the rules by which the entire American food system is organized. And that, as important as it is to "vote with your forks" for change, unless we also vote with our votes, there’s a whole lot that simply won’t change.

The Farm Bill determines what your children will have for lunch in school tomorrow afternoon, down to the number of calories. It determines not only how much, but exactly what low-income women with infants and children will eat for dinner tonight. Even for those meals we Americans pay for ourselves, the Farm Bill to a considerable extent shapes what will be on the menu and how much it will cost. What will be cheaper and more accessible: processed fast food from far away or fresh food grown locally? Will the meat come from animals raised in confinement or outdoors on family farms?

Right now, the Farm Bill encourages American farmers to grow as much corn and soy as they possibly can, and then sell it for less than it costs them to grow it. The result? The best calorie deals in the American supermarket are added fat and added sugar—precisely the sort of calories that are making us overweight and diabetic. Few pieces of legislation have as profound an impact on the public health.

But to speak of the bill’s impact on the American food system does not begin to get at its full impact, which is global. The Farm Bill helps determine the price of corn in Mexico, the price of cotton in Nigeria, and whether small farmers in those places will prosper or fail—stay on the land or migrate to the cities or to the United States. You can’t comprehend the pressures driving immigration without comprehending what U.S. agricultural policy is doing to rural agriculture in Mexico.

The bill determines, to a considerable extent, what happens on nearly half of the private land in the United States. We tell ourselves that we don’t have a national land-use policy, that the market decides what happens on private property in America, but that’s not exactly true: The Farm Bill helps decide what land is farmed and how, as well as what land is restored to grass- or wetland. Few pieces of legislation have as profound an impact on the environment.

Given all this, you would think the politics of the Farm Bill debate would engage the nation’s political passions every five years, but that hasn’t been the case. To a remarkable extent, the bill is decided by a small handful of people—mostly Midwestern farm state legislators and lobbyists for agribusiness corporations. Most of the action takes place behind closed doors, out of the public gaze. Why? Because most Americans take it for granted that the Farm Bill is a parochial piece of legislation mostly affecting Midwestern farmers, and irrelevant, not to mention incomprehensible, to the rest of us. Deeply encrusted with mind-numbing jargon and prehensile programs that date back to the 1930s, it is almost impossible for the average legislator to comprehend, much less the average citizen. It’s doubtful this is an accident.

But there are signs that 2007 will different. To use a word that is much abused, U.S. agricultural policy has become unsustainable, and pressure for reform is mounting. It is full of internal contradictions that can’t be sustained—while parts of the bill concern themselves with improving America’s nutrition, other parts make it nearly impossible to eat healthily. While parts of the bill offer progressive environmental programs, others encourage farmers and concentrated animal feeding operations (CAFO) owners to grow food in the most environmentally destructive manner imaginable.

A perfect storm of political energy and opportunity gives us reason to hope this could be the year for change; constituencies that have never before demanded a seat at the Farm Bill table are insisting they be heard. The public health community has woken up to the fact that, in the midst of an epidemic of obesity and diabetes, U.S. farm policy is, rather perversely, subsidizing the production of high-fructose corn syrup, and treating school children as a Dispose-All for surplus agricultural commodities.

The development community has woken up to the fact that global poverty can’t be adequately addressed without confronting the Farm Bill’s impact on world agricultural markets. The World Trade Organization has ruled that the way the U.S. currently subsidizes its cotton farmers is illegal and must change if trade negotiations are to go forward. And the environmental community has recognized that issues as diverse as clean water, clear air, land conservation, energy, and climate change all need to be addressed through reform of U.S. agricultural policy.

Yes, many of the powerful forces, and political money, that have stood in the way of reform in past Farm Bill debates haven’t gone away. When I mentioned this to a congressman on the Ways and Means Committee, he said that, although that is true, it is also true that political money is no match for the voices and votes of aroused citizens. If the public can be engaged in the Farm Bill debate this year—if citizens can get the attention of legislators in places such as California who have ignored the bill in the past—real change will come.

What does that mean? It means educating yourself on the Farm Bill, following the debate as it unfolds this year, and then, very simply, writing to your legislators to let them know you are paying attention. Let them know that, even though you are not a farmer, you are an eater, and that the Farm Bill is, in truth, a food bill, and so needs to be written with the interests of eaters placed first.

What do eaters want? They want a bill that aligns agricultural policy with public health and environmental needs, with incentives for producing food sustainably and humanely. They want to see a bill that makes the healthiest calories in the supermarket cheaper—and the least healthy calories more dear. They want to see a Farm Bill that feeds children fresh food from local farms rather than surplus commodities from far away. They also want a bill that guarantees farmers fair prices, rather than subsidies, because they want to live in a country that produces its own food and that doesn’t hurt the world’s farmers by dumping our surplus crops on their markets.

You may have other priorities. The important thing is to get them on the table, to expand the circle of people that will decide these questions—because they are momentous, and too important to be decided by a few behind closed doors. Let your legislators know you know the Farm Bill is really a food bill, and it’s time that the eaters were heard.

Journalism professor Michael Pollan is the best-selling author of The Omnivore’s Dilemma. Portions of this article are excerpts from his opening remarks at a recent Berkeley symposium on the Farm Bill.