Ecoscience: Topsoil Erosion

Misguided agricultural policies in the 1970s threw aside decades of sensible soil conservation efforts and caused a dangerous increase in topsoil erosion rates, the authors warned in 1980.

ecoscience - topsoil erosion

Anne and Paul Ehrlich warned that topsoil erosion in the U.S. was exceeding sustainable levels.


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In the midst of today's fuss and furor about our present shortages (and continued depletion) of resources—especially of energy—the accelerating loss of one of our most precious treasures, our topsoil, has gone almost unnoticed, Yet this neglected resource—which is today, and has been in the past, the basis of much of America's wealth—is so slowly renewable as to be virtually irreplaceable.

Recent farming practices, abetted by federal and state farm assistance that has actually encouraged increased crop production at the expense of conservation measures, are leading to unprecedented topsoil erosion—by wind and water—of America's crop and grazing lands. The source of our future productivity is being overused, abused, blown away, and quite literally washed down the river.

How and why is this happening In a country where sophisticated agricultural technology has been almost universally adopted and where farmers have access to state and federal assistance and extension services? Was nothing learned as a result of the disastrous 1930's Dust Bowl? Just how serious is the problem anyway?

Lessons Learned

The Dust Bowl crisis did indeed stimulate an effective national soil conservation program. Farmers were taught—and encouraged through incentives—to employ various techniques that diminish soil erosion and protect fertility.

Among the methods were contour plowing, terracing, and strip planting (the alternation of earth-retaining crops with relatively erosive ones) ... all of which help protect topsoil on sloping land from water erosion. Wind erosion was reduced by planting windbreaks of trees or tall crops.

The depletion of soil nutrients, and both kinds of erosion, were combated with crop rotation ... that is, the planting of a cash crop (such as corn, soybeans, or wheat) in alternate years with grasses or soil-enriching legumes (alfalfa or clover, for example) that provide—in addition—good pasturage for livestock.

Then, in the 1950's, grain production soared as a result of the development of higher-yielding strains, the increased use of fertilizers, and—in some areas—the availability of improved water supply from irrigation projects. Production soon far outstripped demand, and prices began to fall.

To help stabilize farmers' incomes, the government instituted a grain reserve program through which it bought and held surpluses and actively promoted their sale abroad. The "Soil Bank"—which paid farmers to keep a portion of their land out of production—was also initiated at that time. Sensible agriculturists, of course, withheld their least productive fields, which were most often those on hillsides or those with the thinnest, poorest soil. Because this is the kind of land most susceptible to erosion if plowed and planted, the Soil Bank did effectively contribute to the nation's soil conservation efforts.

Lessons Forgotten

However, everything changed In 1972, when—in the face of a 2% growth in the global population—there was a 4% worldwide shortfall in the production of grain ... the basis of the diets of the majority of human beings. One of the worst-hit nations was the Soviet Union, which quietly proceeded to buy over 20 million tons of grain—mostly wheat—from the United States.

Our country suddenly became very hard pressed to meet its domestic demand and other foreign obligations. As a result, grain prices went through the roof in 1973 ... and were soon followed by substantial price rises for grain-fed meat and poultry.

A second major drop in grain production in 1974 aggravated the entire situation, nearly wiping out U.S. grain reserves (which, for practical purposes, are the world's only real food reserves) and bringing on severe famine in several impoverished countries.

The U.S. government's response was to abolish the Soil Bank. (The grain reserve program was already being dismantled by Secretary of Agriculture Earl Butz and friends, whose fondness for "free market" farm policies had a lot to do with the disastrous fluctuation of farm incomes in the 1970's.) Farmers were encouraged by the Department of Agriculture's (USDA) policies -to plant fence-to-fence and boost production by every possible means.

The higher production that resulted, however, was followed by rock-bottom prices, which—together with increased farming costs (mainly a result of increased consumption of fuel and fertilizer) and higher loan interest rates—reinforced the pressure to produce more. In order to stay in business , many farmers had to coax every possible kernel of grain out of the ground, so corn and wheat growers responded to the economic squeeze by abandoning or cutting back on soil conservation practices. The costs of increased erosion would be paid decades in the future ... while the profits gained from bigger harvests were needed immediately. 

Courting Disaster

In 1976 severe droughts reappeared in the western plains, complete with dust storms. Some farmers, unable to make a living, simply gave up and left their bare land to blow away with the wind.

In the Corn Belt, still under the pressure to produce, farmers increased corn and soybean acreage enormously by putting land under continuous cropping. The loss of nitrogen, formerly obtained by rotating cash crops with leguminous pasturage, was compensated for by applying more and more synthetic fertilizers. (Even though soybeans are legumes and do add nitrogen to the earth, they tend to contribute to erosion problems because their root systems don't hold soil well.)

Some farmers gave up strip cropping and terracing on slopes, partly to increase grain production (the alternate crop used in the former techniques had often been less remunerative than the in demand corn and wheat) and partly because such procedures are incompatible with using the latest oversized farm machinery. Worse still, some farmers even completely abandoned the practice of contour plowing!

The most scandalous aspect of all, though, is that such activities have been encouraged—and even financially supported—by the USDA. In recent years, perhaps half of the funds intended to support farmers' conservation practices and paid out through the Agriculture Stabilization and Conservation Service (ASCS) have, In reality, been spent on such measures as improved irrigation and drainage systems ... that do more to increase yields than they do to protect soil.

In 1977, when the Carter administration instituted Its new "set aside" program (the Soil Bank by another name), the ASCS didn't allow pasture to be counted as cropland. So, in order to establish their less-valuable land as "normal" cropped acre age—and thereby qualify it for federal subsidies—many farmers plowed and planted every square Inch of their property in cash crops.

As a result of this lack of attention to conservation, the USDA's Soil Conservation Service warned, in the mid-1970's, that—through water erosion alone—the nation was losing topsoil at an annual rate of three billion tons ... as much as was being lost before the first national conservation programs were established in the 1930's, and twice the amount that should be allowed. The Council for Agricultural Science and Technology (CAST), a private group supported by several mid-western universities, estimated in 1975 that "one-third of All U.S. cropland was suffering soil losses too great to be sustained without a gradual but ultimately disastrous decline in productivity." And in late 1978, Secretary of Agriculture Bob Bergland dramatically announced, "We are on a collision course with disaster. "

Heavy Losses

The most recent—and the most exhaustive—study of this problem is a comprehensive "Soil Erosion Inventory" undertaken by the Soil Conservation Service (SCS) in 1977, and released last spring. It showed that the nation (excluding Alaska) lost some two billion tons of topsoil to water erosion during 1977 and—in ten Great Plains states alone—nearly 1.5 billion tons more to the wind.

Water erosion losses that year averaged four to five tons per acre on cropland, pasture, and range land. Since only the deepest soils can sustain losses at such rates, the average is clearly far too high.

Moreover, the average figure tends to conceal the much higher rates that prevail in some of our most fertile states. Iowa, for instance, loses an estimated 9.9 tons per acre ... Illinois, 6.7 ... Missouri, 10.4 ... and Louisiana, 7.9. (Worse yet, the soil in our Caribbean possessions is being eroded at an average rate of over 40 tons per acre per year!)

Wind damage is a serious problem mainly in the relatively dry Great Plains states and the cultivated parts of the arid West, which are—in turn—not terribly vulnerable to water erosion. The average loss of cropland soil to wind erosion, in the ten states surveyed by the SCS, was over five tons per acre in 1977 ... but in three of those states, losses exceeded eight tons per acre (in Texas, the rate of erosion was nearly three times the average).

The SCS concluded that well over half of the nation's cropland needs conservation treatment ... as does the great majority of our pasture, rangeland, and woodland.

Annual soil losses that can be "tolerated"—that is, the rates at which they can be replenished by natural processes and good husbandry—vary from one to five tons per acre, depending on the depth and quality of the topsoil. (Complete destruction of cropland is—for practical purposes—irreversible. Although severe damage can, in time, be repaired, it can be done only at very high expense in comparison to the cost of conservation practices designed to preserve and protect the soil in the first place.)

With careful husbandry (which includes erosion protection and the regular addition of crop residues and other organic material), new soil can be built up ... at the rate of about one inch per century. Nature, however, takes several times longer.

Lower Yields

So far, fortunately, no serious general decline in national productivity has manifested itself as a result of the recent trends toward "chemical" farming and the neglect of conservation ... probably because soil losses can—for a while—be masked by the application of more fertilizers and other chemicals. But high erosion rates clearly cannot be sustained for very long.

And even though overall U.S. cropland productivity hasn't suffered a decline, neither has it grown significantly since the early 1970's ... and it's quite possible that declining soil fertility, due to over-intensive cropping and erosion, is a factor in that lack of growth.

Soil erosion is a major contributor to national pollution problems as well. In the past decade, our government has made considerable progress in forcing industry to clean up its act. The greatest cause of water pollution today is runoff from what are called "non-point sources" ... that is, mainly farms. Most of the two billion or more tons of soil washed annually from U.S. croplands ends up in our rivers, lakes, and estuaries. The silt fills up reservoirs and clogs irrigation ditches, drainage systems, harbors, and river channels.

And along with the billions of tons of soil go additional millions of tons of fertilizers and pesticides. In two-thirds of the river basins in the United States, water quality is adversely affected by such agricultural pollution.

Poorly managed farms also produce air pollution ... in the form of dust particles blown from unprotected dry land. The ultimate in this form of pollution Is the dust storm, for which the 1930's were famous. Few Americans outside of the plains states realize, however, that such storms recurred in the 1950's and 1970's. (Each generation of plains farmers apparently must learn the same lesson all over again.)

In the United States, a return to sensible policies encouraging soil conservation ironically may come about, not because American agriculturists and the USDA have suddenly become farsighted and concerned about future productivity, but because federal clean water laws require that streams and lakes be "fishable and swimmable" by 1983. And the most effective way to control and prevent the water pollution resulting from farm runoff is to employ conventional soil protection practices. Of course, the effects of such techniques can—and should—be abetted by a curtailed use of farm chemicals.

Yet despite the mandate of our national cleanwater laws, not much is being done. Farmers are still being encouraged by USDA policies—and forced by economic circumstances—to struggle for bigger harvests while ignoring conservation practices and allowing their resource base to be undermined and destroyed.

A Rural Clean Water Program was enacted by Congress in 1977 ... but fell victim, in 1978, to administration budget cutting and bureaucratic wrangling over which agency should run it. No funds were appropriated for the program during that year.

That President Carter, who proudly calls himself a farmer, should head an administration which has consistently slashed funding for soil conservation programs is both astonishing and disgraceful. Such "cost cutting" strikes us as the falsest of economies in a hungry world in which the population is expected to increase by nearly two billion by the end of the century.

A sizable-and growing-number of the earth's people are dependent on U.S. food exports. The U.S., in turn, depends on the $25 billion or more that such food exports earn each year to help meet Its oil import bill.

It remains to be seen how much if any of the damage that has already been done to United States farmland can be reversed. At the very least, we as a nation must do our utmost to prevent any further destruction of our irreplaceable soil resources.  

Sources for this study included James Risser's "Soil Erosion Creates a Crisis Down on the Farm" a series of articles published in the Des Moines Register inSeptember 1978 and reprinted in the Conservation Foundation Letter, December 1978 ... the Soil Conservation Service's 1977 National Resource Inventories (U. S. Department of Agriculture, 1979) ... and William Lockeretz's "The Lessons of the Dust Bowl" which appears in the American Scientist, vol. 66, September/ October 1978, page 560.  

For background material on U.S. agricultural problems, see S.M. Schneider and L. Mesirow's The Genesis Strategy (Plenum, 1976) ... and Chapters 6 and 7 of Paul R. Ehrlich, Anne H. Ehrlich, and John P. Holdren's Ecoscience: Population, Resources, Environment (W. H. Freeman and Co.).  

Paul Ehrlich (Bing Professor of Population Studies and Professor of Biological Sciences, Stanford University) and Anne Ehrlich (Senior Research Associate, Department of Biological Sciences, Stanford) are familiar names to ecologists and environmentalists everywhere. As well they should be. Because it was Paul and Anne who—through their writing and research—gave special meaning to the words "population", "resources", and "environment" in the late 1960's. (They also coined the term coevolution, and did a lot to make ecology the household word it is today.) But while most folks are aware of the Ehrlichs' popular writing in the areas of ecology and overpopulation (most of us—for instance—have read Paul's book The Population Bomb) . . . far too few people have any idea of how deeply the Ehrlichs are involved in ecological research (research of the type that tends to be published only in technical journals and college textbooks). That's why it pleases us to be able to present—on a regular basis—these semi-technical columns by authors/ecologists/educators Anne and Paul Ehrlich.