Academic understanding of carbon and nitrogen cycles is improving a bit.

“Everything is integrated, not only the nitrogen, carbon and climate, but also we looked at land cover and land use changes,” Jain said. “A lot of deforestation and also aforestation and reforestation are going on, and that has a direct effect on the carbon dioxide release or absorption.”

The model accounts for different soil and vegetation types, the impact of climate and the inadvertent nitrogen deposition that results from fossil fuel and biomass burning.

Interestingly, warming temperatures in response to rising carbon dioxide levels could make more nitrogen available, said Xiaojuan Yang, a doctoral student in Jain’s lab. This factor must also be weighed in any calculation of net carbon dioxide load, she said.

“Previous modeling studies show that due to warming, the soil releases more carbon dioxide through increased decomposition,” she said. “But they are not considering the nitrogen effect. When the soil is releasing more CO2, at the same time more nitrogen is mineralized. This means that more nitrogen becomes available for plants to use.”

Increased nitrogen availability allows plants to uptake more carbon dioxide, a factor that mitigates, somewhat, the added burden of carbon dioxide in the atmosphere.

Even so, Jain said, the failure to look at the role of nitrogen in the terrestrial landscape means that countries may be overestimating the amount of carbon dioxide-uptake their forests provide.

People get confused about organic nitrogen. For example, many think that they can spread manure on their fields as fertilizer, by which they mostly mean a nitrogen source. But nitrogen in organic form isn't useful to plants. They need it in a mineral form. Over time soil bacteria can convert organic nitrogen to mineral nitrogen, but they charge for that service. They eat nitrogen as they work. Spreading manure can put soils into nitrogen deficit, just the opposite of what many expect.

A portion of the nitrogen from the organic matter will eventually be mineralized and become plant available. You can think of organic nitrogen as a sort of time-released fertilizer. There are good points and bad points from a growers perspective. It isn't fast acting and makes timing more complicated. Matching nutrient availability to plant growth stage requirements is trickier. But fewer nutrients leach out, and denitrifying soil bacteria are impeded somewhat, leaving more for plants over time - assuming the tricky timing bits have been mastered - even though other bacteria consume some of it to power their conversion work.

While much of this is common knowledge among experienced growers it seems to be new knowledge for ecologists and academics working some of these climate issues. It may help to modify our metaphors. Air and water aren't ever pure in real life. They are cloudy broths containing much more than just a mix of gasses and liquids, and those various ingredients aren't usefully thought of as impurities.

There are some people who have allergies or just get squicked about air and water, and so try to defend themselves, filter and purify, sanitize and medicate their environments. They perhaps imagine a more perfect environment - a clean bubble, a space habitat maybe - where the things they see as being contaminants are excluded. They long to live in an everyday analog of a chip fab clean room.

Fine. But in real life air and water are complex mixes of gasses, liquids and particles. Some of those particles are alive - even miles above and below the surface. If you have already dabbled in some sort of Gaia consciousness you might find it easier to engage with this more realistic view. We are swimming inside the body of a living being - of sorts. The chemistry is very complicated. When we talk about carbon and nitrogen cycles it is good to remember that it is only the largest, most obvious and most usual attributes and facets of those cycles that are included in formal accounts. This is adequate for general purposes under stable conditions, but under changing conditions may prove to be misleading.