Chemicals May Speed Topsoil Loss : Organic Farming Pays Off in Battle Against Erosion

Like most American farmers in the early 1950s, Don Lambert and his father decided to try a new concept that was sweeping across the nation’s farmlands.

So they set aside 25 acres on the 800-acre farm that the elder Lambert had started in 1909 in the rolling hills of southeastern Washington. They used that small parcel to see if the chemicals that had recently become commercially available really would increase the yield of their land while killing the weeds that competed with the crops for the nutrients in the rich soil.

The first year’s harvest looked promising, but the next year they found they had to add far more chemicals to achieve the same result. And the year after that, it took even more.

“We saw that we were just getting sucked in,” Don Lambert said as he sat on a woodpile on the farm he inherited from his father. “So the third year, we just plowed it under.”

They went back to the organic techniques--including growing their own fertilizer--that had turned the land into one of the most successful farms in this incredibly productive region.

And now, all these years later, as Don Lambert looks forward to the day when he knows he will have to turn his farm over to his son, Dan, he has the scientific proof that he and his father made the right decision four decades ago.

In a report with far-reaching implications published today in Nature magazine, scientists have discovered that the Lamberts’ decision to stay with organic farming instead of using commercial fertilizers has spared their land much of the erosion that threatens to wipe out the fertile soils that make this region so rich in agricultural production.

It has taken a lot of hard work, including rotation of crops and physically weeding large areas, but Lambert’s crop yield is only slightly less than some of the conventional farms in this area, and it is slightly more than others.

The region, part of the Palouse River Basin, is one of the most productive farming areas in the United States, but its rolling hills and loose soil make it particularly susceptible to erosion, one of the greatest threats facing American farmers in wide regions of the country, especially the Midwest.

Catches Researchers’ Interest

That was one of the things that interested John P. Reganold, a soils management expert at Washington State University in nearby Pullman, when he began studying Lambert’s farm. Reganold and Lloyd F. Elliott of the federal Agricultural Research Service in Pullman and Yvonne L. Unger, now with the University of Maine, wanted to know whether the few farmers who have stayed with organic farming had gained anything from their hard labors.

What they found here startled them. The Lambert farm is eroding far less than adjacent, but equally well-managed, conventional farms.

“The differences were dramatic,” Reganold said recently as he turned a large auger into the soil to take another sample.

The rich topsoil on the Lambert farm ranged around two feet in thickness. It was about six to 10 inches thinner on the adjacent farm, which switched over to the use of chemicals--now called conventional farming--around 1950.

The finding, Reganold believes, is particularly important because it is based on side-by-side farms. One of them has been farmed organically ever since the soil was tilled for the first time in 1909, and the other has used chemicals extensively since they became available around four decades ago. He believes he has found a laboratory-quality setting where the history is known, the results can be determined, and, in a sense, the future forecast.

What it all means, Reganold said, is that unless farmers in highly erosive areas dramatically alter their techniques, they may be sacrificing the longevity of their farms for short-term yields.

The fine grains that make up the topsoil in this area were literally blown in by the winds over millions of years. The grains slowly blanketed the clay-like subsoils, turning what had once been a barren, volcanic wilderness into a farmer’s dream. With annual rainfall of more than 20 inches, the farms require no irrigation to turn out fields of wheat and other crops.

But because of the rolling topography, rainfall and snowmelt, the area is especially susceptible to erosion.

Above National Average

“Erosion in the Palouse is about 14.1 tons per year (per acre),” Reganold said. “The national average is 8.1.”

Erosion is an insidious problem because in many cases it is almost unnoticeable. A ton per acre is a depth of soil about the thickness of a piece of paper so a few tons is sort of like peeling off a few pieces of paper. But over the years, the cumulative effect can be dramatic.

“It takes so long to form a soil, and you can destroy it so quickly,” Reganold said.

Erosion carries the soil down the hills and into seasonal stream beds, and it slowly migrates out of the area. When enough topsoil is washed away, Reganold said, the yield from the land will be so low that the farms will be unproductive.

That was one of the concerns that led him and his colleagues to the Lambert farm a couple of years ago to begin a long-term study.

“I went into it unbiased, and I came away thinking this (the result) is incredible stuff,” Reganold said.

They took core samples from adjacent areas on each farm, which immediately told them that the topsoil on the Lambert farm was much deeper than on the neighboring farm.

Then they studied both farms when they were “in winter wheat,” and they found that Lambert’s farm was losing its topsoil at only one-fourth the rate of the conventional farm.

The erosion on the Lambert farm was around 3.3 tons per acre, well below the “tolerance” level of five tons set by the U.S. Department of Agriculture. But the neighboring farm was losing nearly 13 tons per acre per year.

Reganold and other experts credit that difference to many factors, but one major element is the use of “green manure”--a crop that is grown and then plowed back into the soil for its nutritional value. Lambert uses winter pea, which he said is “prolific” in its ability to store nitrogen.

Retains Moisture Better

Chemical analysis of the soil from Lambert’s farm showed that it was rich in organic materials, particularly polysaccharides, which act as stabilizing agents that bind the soil together. The soil also retained moisture better.

Other factors are also believed to have contributed to the reduced erosion, Reganold said. Lambert tills his soil less, partly because he does not have to work chemicals into the ground, and he rotates his crops--something many conventional farmers also do--planting wheat in the same area where he grew peas the season before, and so on.

Crop rotation decreases erosion, Reganold said, because “different types of plants offer different types of cover” so that some protect the soil better than others from the impact of water droplets.

“That ranges from row crops, which have a low degree of protection, to grass sod, which has complete protection,” he said.

And since he does not use chemicals to kill weeds, Lambert allows part of his land to “lay fallow” once every six years, giving him a chance to weed the area and further reducing tilling.

He said he has no regrets about the decision he and his father made so long ago.

“My neighbor down the road has a $30,000 fertilizer bill,” he said. “That would make a dent.”

And it could turn out that Lambert’s farm will still be in business long after the winter rains have carried away the rich soils that make some other farms so profitable, Reganold noted.