Green Options » hypoxia

Why “Organic” Fertilizers are Not the Solution to the Dead Zone in the Gulf of Mexico

Steve Savage — Fri, 13 Nov 2009 04:54:52 +0000

From the comment streams and emails I’ve been getting about recent posts, it is clear that many people believe things that are not actually true about the environmental profile of organic fertilizers. I don’t mean to minimize the challenge we face when it comes to fertilizers, particularly nitrogen fertilizers. They take energy to make, have the potential to generate the potent greenhouse gas, nitrous oxide, and can lead to the pollution of ground and surface waters. With a “rap-sheet” like that I understand why people are concerned, but there is a catch - without fertilizers we don’t eat much.

Still, there is a widespread belief that “Organic” fertilizers are the solution. I’ve already blogged about why organic fertilizers are dramatically worse from a greenhouse gas point of view. Today I want to talk about the water pollution issues and why “Organic” fertilizers are actually a much worse problem from that perspective as well.

Why Nitrogen Fertilizers Can Pollute

The reason that ALL nitrogen fertilizers (synthetic and Organic) are a water pollution threat is that they at some point convert to the nitrate ion (NO3-). That particular form of nitrogen is very water soluble so the nitrate can move down into ground water or sideways into surface water. The “Dead Zone” or “Hypoxia zone” in the Gulf of Mexico is driven in some large part by nitrate coming from farms. There are ways to manage this issue, but first I need to talk about the fundemental challenge of crop fertilization.

Marine “Dead Zones” Will Increase, Scientists Predict

Michael Ricciardi — Sat, 25 Jul 2009 21:34:50 +0000

So-called “dead zones”–patches of ocean lacking aerobic (oxygen breathing) life–will most likely increase due to a rise in carbon dioxide (CO2) concentrations.

Because of CO2 build up in the atmosphere, its level of concentration in the oceans also increases. There, some of the CO2 converts to a simple acid called carbonic acid. (H2CO3).

What is becoming a much-studied phenomenon in recent years, these dead zones of depleted oxygen (02) - typically found at depths between 300 and 600 meters–are the result of several factors working separately and in combination: lower sea surface 02 levels, less heat exchanging (”ventilation”) with mid-level ocean depths due to over-all warming, and “euthrophication events” (an over-growth of a species due to excess nutrients).

Ethanol Incentives Contribute to Gulf of Mexico Dead Zone

Clayton B. Cornell — Sat, 20 Oct 2007 13:41:14 +0000

It looks like ethanol subsidies may impede efforts to reduce the size of the Dead Zone in the Gulf of Mexico. A draft report from the EPA Science Advisory Board says that ethanol subsidies could lead to a dramatic increase in nutrient loading in the Mississippi river basin, due to diverting cropland to corn production.

Recent energy policies, combined with pre-existing crop subsidies, tax policies, global market conditions and trade barriers all provide economic incentives for conversion of retired and other cropland to corn production for use in ethanol production. Such conversions could lead to corn production on an additional 16 million acres…

The Dead Zone, an area in which there isn’t enough dissolved oxygen to support aquatic life, has been measured in the Gulf of Mexico since 1985. It’s caused by agricultural runoff overenriching the waters at the end of the Mississippi River - the downstream effect of millions of acres of intensely fertilized crops. Nitrogen and phosphorous, intended for corn but ending up in the river, make their way to the Gulf causing excessive phytoplankton production. In the process, all available oxygen is used up (hypoxia), and marine life has to move out or suffocate.

It turns out that the greater Mississippi-Atchafalaya River Basin (MARB) drains a grand total of 40% of the contiguous United States. The cumulative effect of all this runnoff creates a Dead Zone approximatly 20,500 sq. km. - roughly the size of the state of New Jersey.

To address this issue, the Science Advisory board recommends a 45% reduction in nitrogen and phosphorous fluxes from farmland. Unfortunately, recent trends pushing corn-based biofuels are not exactly aligned with this strategy:

Certain aspects of the nation’s current agricultural and energy policies are at odds with the goals of hypoxia reduction and improving water quality. . .[A]n emerging national strategy on renewable fuels has granted economic incentives to corn-based ethanol production.

Without some change to the current structure of economic incentives favoring corn-based ethanol, N[itrogen] loadings to the MARB from increased corn production could increase dramatically in coming years, rather than decreasing, as needed…

The alternative is cellulosic ethanol and avoiding corn-based fuels altogether:

Alternatively, the use of perennial crops and other feedstocks for cellulosic ethanol requires a more complex refining process that produces more net energy and results in lower fertilization and thus less nutrient runoff than corn-based ethanol.

The Dead Zone in the Gulf of Mexico is a symptom our farming practices, and converting cropland to grow fuel will only exacerbate the problem. This is just another chapter in the corn-based ethanol saga. The EPA’s Science Advisory Board will vote on approval of the draft report in December.

Green Car Congress: EPA Science Advisory Board Suggests Revisions to Ethanol Incentives Necessary to Reduce Gulf of Mexico “Dead Zone”
Science Advisory Board (SAB) Hypoxia Panel Draft Advisory Report

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