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