Too Much of a Good Thing: Combating Nitrogen Pollution

[This was a paper I wrote for my Eng. 101 class Dec. 2013. We were asked to write a proposal/solution essay about some issue. I chose nitrogen pollution.]

When Antoine Lavoisier first experimented with nitrogen in the 18th century, he named it “azote,” which is Greek for “no life.” This was a fitting name, since he observed that mice and fire would both die in a pure nitrogen environment. In more recent years, this old name has taken on a new meaning; while nitrogen is vital for plant growth and helps make more crops than ever before, too much of it can also be deadly in other ways. Here is why: when nitrogen goes into streams and rivers as runoff from farms and dairies, it increases the amount of algae in the water. The algae then does what plants do and absorbs oxygen in the water, which leads to other aquatic life dying. Also, if nitrogen gets into the drinking water, young children are at risk from what is called blue-baby syndrome; nitrogen bonds so strongly with oxygen that a young human body is not able to break those bonds, and so these babies lose a lot of oxygen and turn blue.

How does nitrogen get into the drinking water? Nitrogen occurs naturally everywhere (it is the sixth most common element in the universe), but most of the nitrogen pollution on Earth is caused by humans. Farms use a lot of nitrogen to stimulate plant growth, while nitrogen is also found in dairies and other animal farms, in the manure. Rain washes fertilizer and manure into nearby water sources, or it can even sink into the groundwater if the ground is wet enough. Removing nitrogen from water sources is difficult and expensive, but there are ways to reduce the amount of pollution before it even gets to the water. A few options might be using less fertilizer, keeping nitrogen from running or bleeding off into the soil or atmosphere, and using legumes as a natural source of nitrogen.

More is not always better: farmers can help reduce nitrogen pollution by using less fertilizer on their crops. Nitrogen is essential for plant growth, but research done in Australia has shown that only about 40% to 60% of nitrogen fertilizers put on the plants in their study were actually absorbed by the plant, while research done in Canada and France has shown that fertilizer not absorbed can stay in the soil for decades. Nitrous oxide, a potent greenhouse gas, can bleed off the ground and stay in the atmosphere for 100 years or more. This shows that farmers should use less fertilizer on their plants, because a lot of it is not even needed to help the plants grow. Of course, most farmers do not try and put too much fertilizer on; ideally, they test the soil every growing season and put just enough in. Then comes the next problem: how do they keep the fertilizer from running off? Following are suggestions on how to keep nitrogen-rich fertilizer right where it is wanted.

Australian researchers suggest applying fertilizer only when it is needed instead of before the plants even start growing, since there is more chance that it will simply get washed away without plants to keep it there; to combat this, some farmers do not remove the stubble of the previous crops, but simply plant seeds among the remains of the harvest in the hopes that erosion will be less. Also, although it is easier to turn over soil when it is wet, researchers suggest avoiding that, saying the soil is “especially susceptible to losses following tillage under wet conditions.” Using fertilizer in wet conditions is a problem in the other direction as well, since nitrogen can be carried downward into the groundwater if the ground is too moist. Therefore, farmers need to be careful about how much water they put on their crops, which they should be doing anyway; too much water is bad for the plants. This is not helpful in places like Ireland or Hawai’i, where it is almost always damp. Farmers wet places might try using slow release fertilizers, which, as the name suggests, slowly release their contents over the growing season instead of in one fell swoop. Run-off is also a problem in dairy farms, since there is nitrogen in cow manure. Many dairy farms sell a lot of the manure they produce, but of course a lot of it ends up just sitting there or washing away. Farmers could put excess manure into bins. Planting grass, trees, or other plants between farms and water sources is also an option, because these plants would reduce erosion and absorb a good amount of any escaping nitrogen.

The use of legumes could help reduce nitrogen pollution. Nitrogen is highly non-reactive, but legumes, paired with certain types of soil bacteria, can make nitrogen available for use. Legumes–which include peas, beans, peanuts, and alfalfa–have a symbiotic relationship with a species of bacteria in the soil called rhizobia, which allows the nitrogen in the soil to become available to plants where legumes are planted. In short, farmers should be rotating their crops, with legumes every other season, or planting two crops side-by-side, so that there would less need for nitrogen fertilizers; the nitrogen, in the form of ammonia, would already be there. Farmers do not want to do this because they want to get out as many crops as possible—even though they could sell legumes too. This is not a perfect solution because legumes of course use up a lot of the nitrogen they produce, but it would still mean less fertilizer, which could be just one step towards the ultimate goal of less nitrogen pollution.

The phrase “too much of a good thing” is fitting in this discussion. Like water, food, and oxygen, nitrogen is essential for life, but it can be harmful in large quantities. Though this is a complicated topic with many facets and even more possible solutions, a few ways nitrogen pollution might be kept to the minimum is by controlling how much is used in planting, using natural ways to put it in the soil, and implementing measures to keep it where it is needed to help bring pollution levels down. It is an interesting fact that nitrogen, carbon, and oxygen, three of the most abundant and most needed elements on Earth, are often cited as causing so many problems, mostly because of pollution. Nitrogen is so useful, it would be a shame if it came to be associated with “azote” once more.

featured image from Unsplash.


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