A False Alarm over the Gulf of Mexico's Dead Zone

BRIDGE NEWS September 1, 2000

Just as the Clinton-Gore administration is set to recommend a radical cutback in Midwest farming, the Gulf of Mexico nitrogen problem is looking like a false alarm.

A White House task force claims too much nitrogen from farming is expanding a low-oxygen (hypoxic) zone in the Gulf of Mexico and threatening the marine life.

The administration wants a 20 percent to 40 percent reduction in Midwest farm use of nitrogen fertilizer, despite concerns over how many heartland farms go broke or how much tropical forest has to be cleared to make up for America's smaller farm exports.

The hypoxic zone has shrunk by 78 percent this year, to 1,700 square miles. That's down from 4,800 square miles last year and as much as 7,000 square miles in the years after the giant Mississippi River flood of 1993. The "dead zone" is now the smallest since the drought of 1988, when it was too small to be measured at all, and it has never affected more than 1 percent of the Gulf's area.

We began saying two years ago that the size of the Gulf's hypoxic zone was related to rainfall, not to nitrogen losses from farms that have been declining for 20 years. In fact, the administration's

comprehensive assessment found no ecological or economic damage from the low-oxygen zone finding the administration has suppressed in subsequent reports.

Louisiana, meanwhile, warns that the rich Gulf fisheries can flourish only if adequate nitrogen continues to flow down the Mississippi. The whole idea of a Gulf nitrogen crisis rests on measurements made by a single researcher, sailing her boat along the Louisiana-Texas coastline once each year since 1985. That's not much on which to base radical changes for 1.5 million square miles of some of the world's richest agricultural land.

According to Derek Winstanley, chief of the Illinois Water Survey, historic sources show the "pristine" waters prior to European settlement were, in fact, highly nitrogen-enriched, significantly more so than today.

When farmers started planting corn in Illinois, the soil was so nitrogen-rich that the stalks grew twice as tall as today. Immense concentrations of nitrogen had been deposited by centuries of tallgrass, growing eight feet high.

An estimated 60 million bison, 20 to 100 million prong-horned antelope, unknown millions of elk and deer, billions of prairie dogs and grasshoppers and flocks of birds that "darkened the sky" grazed. The bison wastes alone matched those of about 700 million humans.

The total nitrogen from all these creatures probably equaled the wastes of more than 1 billion people! All the grazing, chomping, digging and bison wallowing also intensified nature's nitrogen production on the whole prairie.

A 75-year experiment with virgin North Dakota prairie found grazed grasslands accumulated over a ton of extra nitrogen an acre compared with ungrazed grass.

The prehistoric grasslands burned almost annually due to lightning and fires set by American Indians to keep the forests back and ensure open grazing for bison and other prey. The burned prairie probably eroded far more severely than today's carefully managed farmlands.

U.S Geological Survey data indicate a pre-European sediment load in the Mississippi basin twice as high as today's ecological hero Barry Commoner wrote that in America, before farming, "the rivers ran clear, except in flood."

History says the opposite. Early explorers found the Illinois River, which flows into the Mississippi, nearly stagnant, covered with green scum and huge rafts of vegetation. The water clarity was apparently only one- third as good as the current Illinois standard for swimming.

Novelist Charles Dickens likened the Mississippi River in the summer of 1842 as "an enormous ditch, sometimes two to three miles wide, running liquid mud, six miles an hour...choked and obstructed everywhere...mud and slime on everything." Nitrogen flowing to the Gulf of Mexico may have reached its lowest point in the 1950s.

A century of cropping without fertilizer had used up the nitrogen in the soil. Yields dropped from 75 to 100 bushels an acre to only 20 bushels by World War I.

Farmers by the 1950s were practicing soil conservation and not yet using much nitrogen fertilizer.

Midwestern cities then produced much less sewage and nitrous oxide (from auto exhausts) than today. Middle American farmers today apply about 9 million tons of nitrogen fertilizer, or about 20 pounds an acre of land in the region.

Winstanley estimates the prairie grasses and animals produced 20 million tons of nitrogen a year in prehistoric times. Virtually all of that burned into the air, with much of it redeposited as nitrous oxides, or washed directly down to the Gulf of Mexico.

It looks as though The Gulf's hypoxic zone is nothing new. In fact, it was probably far larger when Spain's Hernando Cortes went through in 1518. Too bad he didn't stop to measure it on his voyage to conquer Mexico.