Nitrogen level can be too much of a good thing |

Nitrogen level can be too much of a good thing

Tools must be made of the proper materials – steel for a nail hammer, rubber for a soft mallet, for instance.

Our bodies need to perform many jobs that keep us alive. The tools we use are molecules made of specific atoms. Iron, for instance, is very good at combining with oxygen in the presence of water (it rusts). Within every molecule of hemoglobin is an atom of iron, hauling oxygen around in our blood.

We use atoms of nitrogen to make the proteins found in hair, nail and muscle, and also to make enzymes, the molecular machines that make and break other molecules.

Even though the air we breathe is four-fifths nitrogen, it’s virtually useless for making proteins. Atmospheric nitrogen is composed of molecules in which nitrogen atoms are locked together in pairs.

Breaking a nitrogen molecule apart is not completely impossible. Whenever a million-degree bolt of lightning flashes in the sky, lots of nitrogen molecules are ripped apart, their atoms freed to combine with atoms of oxygen to form nitrogen oxides. When nitrogen oxides dissolve in raindrops and fall to Earth, they can be absorbed and used by plants, which in turn are eaten by animals.

Were lightning our only source of nitrogen fertilizer, there would not be enough food, either for plants or for animals, to inhabit the Earth as abundantly as we do.

Find a plant of the pea family and pull it out by the roots (feel free to pull up as much nonnative Scotch broom as you can!). Small nodules on the roots provide growth chambers for bacteria that absorb air from the soil to accomplish what otherwise requires a bolt of lightning – they break apart nitrogen molecules then combine nitrogen atoms with oxygen to make fertilizer.

Using heat and pressure, humanity learned to duplicate this feat a century ago. (Making nitrogen fertilizer is highly energy-intensive; subsidized by cheap fossil fuels, we’re in the unique – some would say dangerous – position of putting more energy into raising our food than we get out. Should the price of fuel go up, so would the price of food.)

Whenever we concentrate something – put it in a “pile” – nature does her best to spread it around.

The Mississippi River drains two-fifths of the land area of the lower 48 states, including virtually all of the Midwestern farm belt. Fertilizer and livestock manure drain into the river, which carries them into the Gulf of Mexico. With unlimited fertilizer, algae in the gulf thrive – they “bloom.” Then they die.

Dead algae rot, which is to say they’re eaten by bacteria which obtain energy by combining their food with oxygen. Eating the superabundance of dead algae, the bacteria soon use up all the oxygen in the water around them. The result is a perennial “dead zone,” stretching for miles into the gulf, in which nothing that breathes oxygen can survive.

Factories make fertilizer with heat and pressure, conditions also found in car engines and the boilers of fossil fuel power plants. Tailpipes and smokestacks inject humongous amounts of fertilizer into the air daily.

At first blush, fertilizing the Earth might seem like a good idea … until we realize that the mix of plants and animals around us have evolved in an environment where nitrogen’s pretty scarce. Changing the availability of fertilizer will change the mix of plants and animals. As in the gulf, the change is not likely to be desirable.

Trained as a biologist, Alan Stahler is also an amateur astronomer. He teaches biology and geology at Bitney Springs Charter High School. His science programs can be heard at noon on alternate Tuesdays on KVMR-FM (89.5).

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