Thus far in the presidential debates, no mention has been made about land and water conservation or the environment in general. Not a word about climate change. Nothing about the federal farm bill hung up in Congress and what it portends for crop land erosion, river siltation and wildlife habitat. Nor an utterance about the 40th anniversary of the Clean Water Act and its gutting in recent years by the U.S. Supreme Court.

Least surprised by these non-mentions are longtime observers of conservation politics. They know that, like gun control and abortion, the "environment" has become a third rail of American politics: hot, and potentially fatal.

The political calculus works like this:

Because some environment and animal-protection groups have proven themselves over time to be more interested in pushing their own political and personal agendas while masking their efforts as resource stewardship, few politicians want to carry their water publicly -- or, even, unfortunately, the water of more sincerely productive environment and conservation groups, fearing constituents will associate one with all.

Similarly, many in this country deny (or don't care) that the environment and, more broadly, the Earth, are suffering greatly under the weight of post-modernism.

The political muscle of this bunch, which spans all social-economic strata, is considerable. Often they need only to reference that one regulation or another will cost the country jobs, or subtract from the bottom lines of this industry or that, and for many politicians, risk-averse as they are, thoughts of the environment, or conservation, are out the window.

Between these two immoderations plod the rest of us, the great majority, plenty busy, one and all, trading a day's work for a day's pay, while hoping, regarding the environment, our political leaders balance exploitation with protection.

Uncomfortable with zealotry, we understand that everyone wants a job and most everyone wants to make more money next year than they do this year. But on our days off, we also enjoy camping in a park, hiking in woods left untrammeled, swimming in a clean lake or river, watching an autumn sky filled with waterfowl, and hiking for pheasants or other game with a gun in our hands.

Helpless on our own to ensure the continuation of these life-enriching opportunities, just as we are unable to provide our own police and fire protection, or build our own roads, we depend on our leaders to ensure their continuation, without diminution, forever. These activities, after all, and the wildlife and wild lands and waters upon which they depend, are rooted deeply in our individual souls and the nation's collective psyche, and have helped shape who we are as a people since the nation's founding.

Some leaders have understood this (Teddy Roosevelt) and prioritized conservation. Others (most) have comprehended it, but for lack of backbone couldn't resist the temptation to cash in politically, or financially, by selling, in various forms, the nation's natural heritage to the highest bidders.

Still another class of politicians -- ever larger as we evolve into a more urbanized society -- simply don't "get it."

This last, in my view, includes Mitt Romney and President Barack Obama. Both largely represent, and reflect, the nation's political class as presently composed, in that each suffers from what could be described as a poverty of geography; a lack of personal, experiential grounding in the nation's landscape.

Ask either of them, for example, why a conservation compliance provision should be included in the next farm bill, linking crop insurance participation to wetland and grassland protection, and each (both being smart and highly educated) perhaps could delineate the respective, and conflicting, positions of the "farm industry" and conservationists.

But neither will have known firsthand the heartbreak of watching a 20-bottom plow bust a native prairie, and the scattering thereon of bobolinks, upland sandpipers and short-eared owls.

Nor will they be able to imagine, from their own days afield, the further wetland drainage that will result if the House wins its farm-bill battle with the Senate, excluding conservation compliance; an outcome that should be calculated less as a statistic than, more accurately, as additional nails in the coffin of biological complexity. Not just for ducks, geese, muskrats and untold shorebirds and other wildlife. But for people.

Roosevelt said:

Here is your country. Cherish these natural wonders, cherish the natural resources, cherish the history and romance as a sacred heritage, for your children and your children's children. Do not let selfish men or greedy interests skin your country of its beauty, its riches or its romance.

Perhaps someday climate change or another natural calamity resulting from the priority perversion that defines today's politics will prompt us all to act -- not only our leaders, but those of us in the great majority who through our indifference enable them to remain silent on these important matters.

Until then, don't expect environment stewardship to be debated anytime soon, perhaps least on Monday, during the last presidential debate.

Dennis Anderson • danderson@startribune.com • Twitter: @stribdennis