Agriculture In The News

Here are a couple of ag pollution stories.  First, Minnesotans Pay a Price for Crop Fertilizer at Faucet (h/t Big Picture Agriculture):

In Minnesota, three-fourths of people get their drinking water from groundwater. On average, 6 percent of private wells are contaminated with nitrates. About a dozen community water systems have "pretty severe nitrate problems," said Bruce Montgomery, manager of the Agriculture Department's fertilizer and pesticide division. Health officials say that once or twice a year another community hits the limit.
The problem is concentrated in several regions: Dakota and Washington counties; the 14 counties that make up the Central Sands region in the middle of Minnesota; the southeastern "karst'' region, where the cracked limestone geology sends water straight down to the aquifers, and southwestern Minnesota, where a shortage of water in general aggravates the nitrate problem.
In Dakota County, the first place in Minnesota to trace nitrates directly to agriculture, the problem is partly an accident of geology. West of Hwy. 52 a thick layer of till -- clay, gravel and sediment left behind by the last glacier -- lies beneath the rich soil, so that water percolates slowly down from the surface.
But on the county's eastern side, the melting glaciers left behind sand on top of bedrock, and water rushes through it like a sieve -- down to the aquifers or into the Vermillion River and eventually the Mississippi River, said Tim Cowdery, a U.S. Geological Service hydrogeologist who has studied it. Carlson's husband, she said, describes it as "young water."
Geology wasn't as much of a problem back in the day when farmers planted more varieties of crops, many of which required less nitrogen. But in Dakota County, like much of Minnesota, corn and soybeans are now the primary crop. Soybeans pull nitrogen out of the air and fix it in soil, where it can leach into the water. And corn, more than most any other crop, demands fertilizer to produce the yields that have climbed steadily for decades.

Also, while not just an agriculture story, Harmful Algal Blooms Increase as Lake Water Warms:

A lake restoration program at Lake Zurich effectively eliminated phosphorus-rich pollution caused by sewage and fertilizer runoff from lakeside towns and tourist areas. Once phytoplankton and algae were deprived of a needed nutrient, scientists and hydrologists reasoned, the toxic blooms would be a thing of the past.
For a while, it seemed the lakes were once again going to be clear, safe and attractive to vacationers. But researcher Thomas Posch, a scientist at Lake Zurich's Limnological Station, part of the Institute of Plant Biology at the University of Zurich, discovered that despite decades-long remediation efforts, certain toxic phytoplankton populations are once again on the rise.
Posch has been studying Lake Zurich for more than a decade. He found that increasing average air temperatures and ensuing changes in surface water temperature have provided P. rubescens the ideal conditions to live and bloom in near-epic proportions.
"During the 1940s through the 1950s, all of the lakes in western Europe were affected by raw sewage," Posch said. "Then in the 1970s, we started to treat wastewater. Problem solved." Or, he added, so we thought. His measurements have shown that since 1990, despite the drastic decrease in phosphorus, the whole lake biomass of P. rubescens has been rising. One reason is that P. rubescens doesn't need a lot of phosphorus. It thrives on nitrogen.
"Nitrogen concentrations haven't dwindled much," Posch added. "The chemical mix of the lake now favors P. rubescens."

This probably doesn't bode well for Lake Erie and Grand Lake St. Mary's.  It also doesn't bode well for agriculture.