Main Street Project


Perennials and the Dead Zone

Hazelnut and Corn(Not the Stephen King movie with Christopher Walken. Good movie, though, right? Remember that final scene where Martin Sheen holds up a baby as a shield against assassination, thereby destroying his own presidential bid? For some reason that scene has been replaying in my head lately. Anyway, not that.)

We’re big fans of perennials plants at Main Street Project. They’re kind of a Swiss army knife for paddock poultry farmers. They provide the chickens with cover from aerial predators and excessive sun. They cool the soil to reduce evaporation. Their deep root structures both minimize soil erosion and hold more than their own against weeds, acting as a natural herbicide. They are efficiently fertilized by the chickens they shelter. The perennial hazelnuts and elderberries we cultivate on our farms bring in additional income.

And more evidence is emerging about the capacity of perennials to dramatically reduce deadly nitrogen runoff.

For those unfamiliar with the dead zone, let me briefly explain. At the mouth of the Mississippi river there is a large area that is hypoxic, meaning that oxygen is at dangerously low levels. Most things can’t live without oxygen, thus “dead zone.” There are hundreds of these hypoxic areas, but the one in the Gulf of Mexico is the second largest in the world. In 2015 it spanned 6,474 square miles, “an area about the size of Connecticut and Rhode Island combined,” larger than NOAA had predicted, and 1,300 miles2 larger than 2014.

National Geographic has an excellent, readable overview on how dead zones are formed and why they matter here, but in case the heat is diminishing your attention span, I’ll oversimplify for you. Eutrophication (excessive nutrients in water) increases the growth of cyanobacteria, or “blue-green algae” (It’s bacteria, not algae.) as well as phytoplankton and actual algae, which block sunlight and oxygen at the surface of the water. Not good. Then, when these organisms die, they sink, and their decomposition process eats up most of the oxygen that now manages to get through. This has a particularly devastating effect on sea life nearer the ocean floor, which impacts the health not only of shellfish, but fish, birds, and humans and other mammals.

But what causes eutrophication? Yep: industrial agriculture! There are other anthropogenic (human made) causes of dead zones, but in the US and other “developed” countries, excessive nutrient runoff from farms is the number-one contributor. Nature has some impressive filtering techniques, but the more overloaded creeks and streams get, the less able they are to filter out excessive nutrients, which then travel into major waterways. Synthetic fertilizers and animal manure are the top contributors to nitrogen runoff into the Mississippi and, from there, the dying Gulf.

Perennials reduce runoff. Their long root structures trap and absorb water and nutrients before they leach into the soil and pollute surrounding waters. It’s one of the many reasons they play an essential role on MSP farms. Iowa State University has done computer modeling that is consistent with other research in showing the potential for perennials to significantly clean up our waterways.

[Assistant Professor of agronomy] VanLoocke’s study, published in the peer-reviewed academic journal Global Change Biology Bioenergy, found that perennials could reduce nitrogen runoff by more than 70 percent on farmland where they’re planted, a figure that closely mirrors the conclusions of the Nutrient Reduction Strategy. 

Seventy percent! The impact this could have on runoff from conventional farms is enormous. While it will not come close to solving all the problems of industrial farming, improving the health of our water is kind of important. And who knows? Maybe the introduction of a non-corn, non-soy crop onto conventional farms could be the gateway to agroecological, integrated farming. Maybe that will open eyes to the symbiotic relationship between soil, animals, crops, and water on a resilient farm. They’ll look for more sustainable, regenerative ways to change, and….

We know enough about the lock ins of industrial agriculture not to hope for such things. But it would be great if this study encouraged concerned farmers to introduce perennials and reduce agricultural runoff. Meanwhile, Main Street Project will keep improving and expanding our paradigm-shifting system, and applaud any efforts to minimize the destructiveness of the dominant one. Because it’s not about us. It’s literally about saving the world.


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