New research shows organic farming can help curb nitrogen pollution

Important new research from the University of Virginia in collaboration with The Organic Center shows that organic farming can help reduce nitrogen pollution on a global scale. On the heels of The Organic Center's groundbreaking study last year showing how organic soils help to diminish climate change, this latest study offers even more solid proof that organic food and farming create a cleaner global environment.

Climate change. Smog. Acid rain. Dead zones. The ozone hole. These are more than environmental buzz words. These are real issues affecting the planet, and nitrogen pollution plays a key role in each of them. Plants need nitrogen to grow, it is essential to life on earth and is present in all living systems. But too much of that same nitrogen can cause environmental problems. The University of Virginia and The Organic Center collaboration finds that organic farming – through its recycling of nitrogen – contributes far less to the pool of new reactive nitrogen in the environment and can help to alleviate the critical problem of nitrogen pollution.

"Agriculture adds a large amount of nitrogen into the environment during the food production process," said Dr. Jessica Shade, Director of Science Programs for The Organic Center. "This very timely research shows that many common organic farming practices, like composting and the use of manure fertilization in place of synthetic fertilizers, can recycle reactive nitrogen already in the global system rather than introducing new reactive nitrogen into the environment. Organic farming thus has a much smaller environmental impact on the global scale."

The study, led by a team of researchers in Dr. James Galloway's lab at the University of Virginia, found that while organic and conventional farms have comparable on-farm nitrogen losses for crops systems, organic farming helps prevent nitrogen pollution by recycling three times more reactive nitrogen than conventional.

The study also found that almost all of the nitrogen used to produce the food in a conventional food-based diet – 93 percent -- was newly created reactive nitrogen. In comparison, for an average diet of organic foods, only 33 percent of the nitrogen used to produce the food was new reactive nitrogen. The rest of the nitrogen used for plant growth in organic production was already in existence and was being recycled.

Organic maximizes the benefits of nitrogen but limits the harm

Nitrogen in some form is required for all life. Most nitrogen is found in the air and can't be used by plants or other living things, and does not contribute to air or water pollution. But when that nitrogen goes through a chemical process, it becomes reactive. Reactive nitrogen is what's used for plant and animal growth, but reactive nitrogen also can cause a host of environmental problems. More and more of the benign nitrogen on earth is getting transformed into the reactive form, primarily through the creation of synthetic fertilizer.

Agriculture uses a huge amount of reactive nitrogen to grow crops, and much of that nitrogen is lost to the environment during the food production process. As the reactive nitrogen moves through the environment, it creates a cascade of detrimental environmental impacts.

Excess reactive nitrogen contributes to climate change. Fertilizer can get converted into nitrous oxide, a greenhouse gas 300 times more powerful than CO2. Nitrous oxide can enter the stratosphere and eat away at the ozone; it's an important contributor to ozone depletion right now. Reactive nitrogen forms smog and contributes to acid rain when converted to nitric acid.  Nitrogen runoff gets into lakes, causing toxic algal blooms. Nitrogen runoff pollutes oceans, leading to oxygen loss and killing everything in giant areas called "Dead Zones." In 2017, the dead zone in the Gulf of Mexico was the size of New Jersey – the biggest ever seen.

The nitrogen challenge is to maximize the benefits of reactive nitrogen, while minimizing the negative environmental and human health impacts.

Organic does not use synthetic fertilizer. All the nitrogen on organic farms comes from recycled sources like compost/manure, or a small amount of new reactive nitrogen from nitrogen-fixing bacteria in the roots of cover crops or other legumes. Those same sources also build a complex and rich soil able to hold onto nitrogen longer rather than just allowing it to run off the field.

The research is one of the first studies to quantify on a global scale how much organic practices contribute to nitrogen pollution versus conventional practices. The results show that organic far exceeds conventional in recycling nitrogen. Conventional farming relies heavily on the creation of new reactive nitrogen: 60 to 100 percent of conventional inputs are from new nitrogen sources. Organic farms primarily utilize already existing reactive nitrogen: 80 to 95 percent of organic's inputs are from recycled nitrogen sources. The study found that organic production releases 64 percent less new reactive nitrogen to the environment than conventional production.

"Since nitrogen is an element, it cannot be created or destroyed," said Dr. Tracy Misiewicz, Associate Director of Science Programs for The Organic Center. "The total number of nitrogen atoms on Earth remains constant, so we need to understand what proportion of the total is present in a polluting form vs. a non-polluting form. This research shows that rather than converting benign nitrogen into polluting nitrogen, organic farming practices overwhelmingly recycle reactive nitrogen instead of introducing new reactive nitrogen into our environment."

The study results will be presented at The Organic Center's 15th Annual Benefit Dinner on March 8 at the National Products Expo West trade show in Anaheim, California, and also at a research release event on March 9 on the floor of the trade show. For more information on The Organic Center and the science behind organic food and farming, visit

science, runoff, fertilizer, climate change, eutrophication, nitrogen pollution, smog, acid rain, ozone hole, Dead Zones