December 19, 2007

Record US corn acreage spark pollution worries on US Gulf

Record corn acreage in the US is leading to higher pollution near the Gulf of Mexico as agricultural runoff from greater volumes of fertilizers applied seep into coastal areas through rivers.

Nitrogen-based fertilizers applied on crops in the Midwest seep into the Mississippi River, which run through the Corn Belt states. As corn absorbs fewer nitrogen compared to other crops, more of the fertiliser running off into rivers, which eventually joins the sea at the Gulf.

The fertilizer that accumulates there leads to algae blooms. When the algae dies, it decays and uses up oxygen, creating a oxygen-depleted zone.

The "dead zone", spanning 7,900 square miles, discovered nearly two decades ago, has been growing steadily, impacting fishing communities near the Gulf.

This year,  the zone became the third-biggest on record. It was larger in 2002 and 2001, when it covered 8,500 and 8,006 square miles respectively.

The dead zone typically begins in the spring and persists into the summer. Its size and location vary each year because of currents, weather and other factors.

The boom in corn demand is worrying scientists and environment watchers as this meant an even greater acceleration in the expansion of the dead zone.

Environmentalists had hoped to cut nitrogen runoff by encouraging farmers to reduce their use of fertilizer and establish buffers along waterways.

However, the doubling of corn prices within four years has meant a rush to plant corn. US corn acreage hit its highest level this year since 1944.

According to the Environmental Protection Agency, up to 210 million pounds of nitrogen fertilizer enter the Gulf of Mexico each year.