If the U.S. government's farm policies over the last few decades had been as botched as its urban policies, probably we would all be dead of starvation.

The same can be said about urban research and technology. While farming, like communication and manufacturing, has been revolutionized in this century and we have all become used to computers and space rockets, our cities -- in fact, everything that has to do with organizing and building human settlements -- have been strangely stagnant.

The massive and expensive urban research we launched after the riots a dozen years ago has yielded mostly jargon and statistics, neither being very helpful.

Technologically, there has been no important urban breakthrough since the elevator and the streetcar were invented in the 1850s and automatic traffic lights were introduced in the 1930s. Minor breakthroughs, such as Metro's farecard machines, keep breaking down.

None of the promises of industrialized housing construction (to get us more decent shelter for less money) or of monorails, "skybuses" and "dial-a-ride" (to get us there without cluttering the world with combustion engines) has proven economically practical.

Feasibility aside, no one really wants the city, or "non-city," that the futurologists keep predicting. Who wants to stay home all day and earn his living by pushing videocomputer buttons in the new "electronic cottage industry" that Issac Asimov says will replace offices, factories and cities? Who wants to live in the "disposable post-urban homes," not built, but sprayed with polyuretham foam, that Eugene Raskin has in store for us?

The truth is that through the confident 1950s and the turbulent 1960s our "affluent society," as John Kenneth Galbraith called it, had no clear idea of what it did want in the way of a living environment.

We took what we could get, and what the federal government gave us were the FHA loans and freeways of suburbia. The cities and the intellectual vacuum left behind were filled with dreadful mistakes.

In the 1970s we learned what we did not want. We recognized the mistakes. We blew up a high-rise housing project called Pruitt-Igoe. We stopped the freeways from tearing up the cities and we replaced urban renewal with loving rehabilitation of old buildings.

As we enter the 1980s, most of us finally know what a good place to live should be like, but now we no longer seem to have the money to build it.

Luckily -- or perhaps unluckily -- what we need most, however, is not money and hardware so much as the will to overcome narrow parochialism within our local jurisdictions and the flexibility to reform the real estate tax system.

But spending money or building some monster, even spending or building foolishly, has so far seemed easier than breaking old habits. The American people, experts say, just will not hear of regional planning and real estate tax reform. This leads to a vicious circle. The American people do not hear about it because the experts think it is hopeless to tell them.

There is now some hope, however, that California's Proposition 13 may herald relief. A recent report by the House subcommittee on the city, chaired by Henry S. Reuss (D-Wis.), sees the property tax rebellion not as a disaster, but as a "prelude to new opportunities."

So far the great tax revolt of 1978, which has been compared to the Boston Tea Party, seems nothing but the defeat of all efforts to clean up "the mess that is man-made America," as someone put it.

Among other things, when two-thirds of California's voters on June 6, 1978, backed a drastic cut in property taxes, they also indirectly, cut back the Carter administration's urban program announced two months earlier.

In a catch-all sort of way, Carter's urban policy reflects, I believe, current collective hopes and priorities for our metropolitan areas. They are modest enough. As the latest Harris survey on the subject has shown, we don't want "non-cities" and "post-urban," disposable polyurethane foam houses. What the majority does seem to want, and what the Carter policy promises, is "urban conservation."

In city and suburbs, America wants to settle down, clean up the place and make it safe.

We want to strengthen neighborhoods and the neighborhood spirit. We want a sense of identity and belonging. We like to see megalopolis not as a sea of anonymous buildings, billboards and traffic jams, but as an aggregation of Norman Rockwell small towns, where the grocer saves prunes for you and the policeman drops by to tell you your car lights are on.

We want open space and greenery, along with a nearby pastrami-on-rye at 3 o'clock in the morning.

Not that the Carter program could provide and instant idyll. But it might, slowly and creakingly, get us started toward urban conservation by revamping federal policies and aid mechanisms.

The president thought this would take $13.6 billion in budget authority for 1979 and 1980.

Due mostly to the fear Proposition 13 had struck in the hearts of Congress, Carter received $2.5 billion -- 18 percent of what he had requested.

To the extent that we rely on federal funds, we now must move 82 percent more slowly and creakingly toward a livable living environment.

But government, politicians, civic leaders and experts can also go back to the people and say, in effect, "Okay, if you are sick and tired of paying local government for worsening the mess, insist that government does better, more effective planning. If you are sick and tired of paying property taxes and getting too little in return, change the tax system to make it more effective."

None of America's 5,000-odd counties is an island. No rural, suburban or city jurisdiction can create a pleasant environment, assure a harmonious balance of rich and poor people, run good schools, control crime, excessive commercialism and land speculation, provide parks and playgrounds, keep traffic moving smoothly and protect the ecology, if a neighboring county is a mess.

It is ridiculously simple: The balkanized jurisdictions within our metropolitan regions either plan together or deteriorate together.

Councils of government such as the one we have in the Washington metropolitan region are a beginning. They collect data, identify problems, set goals and assure some degree of cooperation. That is essential, but not enough.

There are also a few regional planning agencies in this country, notably the Northeastern Illinois Planning Commission. How well they do is hard to tell. Because they have no power of enforcement, most of their plans remain untested.

In the end, American taxpayers can only get better services and greater benefits for their money, in the same way American corporation stockholders get more profit from their investment: with good, workable product design, efficient production methods, sound management, elimination of waste and duplication, sensible research and pooling of all available resources. A corporation that is an agglomeration of partly bankrupt, partly affluent, partly progressive, partly retarded, squabbling, competing and jealous small businesses will not survive for long.

In the 1980s, perhaps, America's local politicians will learn to understand this.

The decade also may be one of property tax reform, an effective answer to Proposition 13 complaints.

As the Reuss report puts it, "Under the current operation of the property tax, the more one invests in a home, the higher the property tax. No matter that this investment puts people to work and improves the neighborhood. No matter that just about everybody wrestling with urban problems decries the loss of city jobs and the decay of neighborhoods. Those who act to improve their properties receive a stiff financial punishment for their good behavior. Commercial and industrial property improvements similarly are burdened with taxes in direct proportion to the social benefits they sow.

"In short, the better one uses property -- the more people it houses or puts to work -- the higher it is taxed. Abusing or wasting property are the occasion for lowering one's tax."

Some experts would therefore eliminate property taxes, but that, the Reuss report says, neglects the fact that the other part of the tax -- the tax on land values -- is one of the best weapons for improving land-use patterns.

Low land tax encourages land speculation, which ultimately raises the costs of housing and other development to intolerable levels. If a speculator has reason to believe land values will rise, he will play the waiting game, holding the land out of the market, covering his holding costs with porno shops, ramshackle apartments and -- most notoriously -- surface parking lots.

If land taxes are high but housing and other building improvements on the land are exempted or partly exempted from taxation, we discourage blight and sprawl caused by land speculation and encourage productive, compact development.

What we need is to tax the land but not the buildings on it, as simple strategy which, to judge by the good results where it has been tried, is too promising to be ignored much longer.

With any luck, the future of suburbia and of metropolis spells a decrease in federal botching and spending and a reassertion of local initiative. A better living environment requires sound planning and plan enforcement. That is a matter for local governments working under a national urban policy.

Most of what happens in our cities and suburbs happens not by government, but by commerce and industry. But government must guide this powerful force so it becomes more responsive to the needs of urban America.