CEDAR RAPIDS — Farmers’ productivity increased at an “extraordinary” rate of 1.42 percent a year from 1948 to 2011, according to a study by the U.S. Department of Agriculture.
Those productivity gains were achieved at least in part, however, at the expense of largely uncalculated nutrient-pollution costs passed on by farmers to the general public, according to agricultural economists and environmental advocates.
USDA researchers found that agricultural output nationwide since 1948 grew at 1.49 percent per year with nominal growth in total input use.
Total factor productivity, which takes into account the growth in inputs — seeds, fertilizer, water, pesticides, plus all the other costs of production, most notably the capital costs of land and machinery and the costs of labor — increased 1.42 percent per year from 1948 to 2011, the study found.
During that 63-year period, soybean yields have doubled and corn yields have quadrupled — gains achieved with a 25 percent reduction in cultivated land and a 78 percent reduction in labor, according to lead author Sun Ling Wang, an economist with the USDA’s Economic Research Service.
The principal beneficiaries of farmers’ increased productivity, Wang said, are consumers. While yields have increased, she said, inflation-adjusted prices of agricultural commodities have fallen dramatically, enabling U.S. consumers to spend a much lower proportion of their income on food.
Wang said much of the productivity gains were achieved through bigger equipment, more extensive ag drainage, genetically modified seed and increased use of commercial fertilizer, herbicides and other chemicals. Several of those factors, along with the widespread row crop replacement of hay, pasture and small grains, have contributed to increased nutrient pollution of water.
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In Iowa, fertilizer inputs have increased more than sevenfold from 1960 through 2004, according to another USDA study. During the 44 years included in that study, the average annual increase in fertilizer use in Iowa was 4.54 percent.
During that same period, Iowa posted an 8.78-fold increase in chemical use. Its 4.94 percent average annual rate of increase was behind only the comparable rates for South Dakota (7.86 percent) and North Dakota (5.65 percent), both of which started in 1960 with nominal chemical use.
Wang said she and her colleagues did not take into account environmental costs, which she described as important and interesting but hard to define and quantify. Other researchers have reached similar conclusions.
One of the few published studies of externalized pollution costs concluded in 2008 that at least $4 billion a year is lost as the result of the degradation of freshwater sources.
Kansas State University ecologist Walter Dodds, the study’s lead author, said he thinks that $4 billion figure remains valid and is, “if anything, an underestimate.”
Dodds and his colleagues calculated monetary damages by examining, among other factors, losses in lakefront property value, reduced fishing and other recreational activities on affected lakes and the cost of purifying drinking water.
Though it’s “harder to put a dollar value on it, algal blooms caused by excess nutrients are harming biodiversity. Fish and aquatic invertebrates are taking a hit,” Dodds said.
Acknowledging the difficulty in quantifying externalized costs of nutrient pollution, Iowa State University economics professor Catherine Kling said the Iowa Nutrient Reduction Strategy provides insights. The strategy’s authors estimate the cost of achieving its goal — a 41 percent reduction in nitrate load and a 29 percent reduction in phosphate load from agricultural sources — would range from $77 million to $1.2 billion a year.
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While farmers would assume some of the burden in direct costs and reduced production, much of it would be borne by taxpayers.
One entity that can provide a solid accounting of its externalized nutrient pollution costs is the Des Moines Water Works, which is suing three northwest Iowa counties, seeking to regulate nitrate discharges from tile drainage districts to the Raccoon River, a source of its drinking water.
In addition to the $4 million construction cost of its denitrification facility, since 2000 it has spent another $4 million to operate and maintain it, the utility said, adding that nitrate removal costs last year and this year alone topped $1.5 million.
“We understand the importance of ag tile drainage, but someone has to step up and be accountable for its downstream effects,” said CEO Bill Stowe.
ISU agricultural economist Chad Hart said “you have to be impressed” with farmers’ productivity gains, which have made U.S. food prices “incredibly low when compared with the rest of the world.”
Still, he said, it’s “a fair question” to ask how agricultural productivity gains have affected the environment and how some of the costs of those gains have been passed downstream.