I had always thought that the nitrogen in snow, rain, and thunderstorms was a good thing. But I've been doing some reading about how there is more nitrogen in places with more pollution and combustion, and how it's increasing at a pretty fast rate. I can't really understand if it's purely a good thing, or if it is something that we don't want more of. (not that we can do anything about it, other than move our gardens to Samoa.)
Can anyone explain this simply to me? Thanks!

In the air, excess N "evaporated" from ground sources in the form of nitrous acid can bind to pollutants in the air bringing it all back down to the ground. In polluted areas this also brings metals and generally a lot of sulfur with it, too.

Good for the air, but not so great for the soil because the pollutants brought down generally have a greater impact than the returned N.

Take a look at the Los Angeles skyline in early/mid 1980s movies. That's scarey air. For anyone that's been in LA in the past many years and can still see how polluted it is, it's scary it used to be worse 25 years ago.

Here in NC there's little S addition to soils because of the amount of rainfall we get bringing atmospheric S that's supplied by the sheer amount of chicken growing operations in the state.

Our air quality, even in the bigger cities, is mostly good except on high ozone days, though.

"Atmospheric nitrogen compounds
cycle to the land and water through
atmospheric deposition. Wet deposition,
predominantly rain and snow, carries
nitrate and ammonium."

My specific question at this point is this: they're calling it "inorganic Nitrogen" and it has increased because of man made combustion. I had always heard that the reason that chemical fertilizer kills the microorganisms in the soil is not because of the type of P or K in the fertilizer, but the type of N in chemical fertilizer, which acts like a salt and kills the little critters the way a salt shaker kills slugs. So, we organic gardeners use what we think of as "organic" N, in blood meal, manure, etc. Does "inorganic N" coming from the sky mean it is NON organic, as in it's the same N as in Chemical fertilizers? Or does the designation "inorganic" mean something else? Or am I just bored because it feels like spring but I can't plant yet??? :)

Learned something new today!

In cooking, salt (aka table salt) is sodium chloride. In chemistry, salts are compounds which result from the reaction of an acid and a base. Sodium chloride is just one such compound. Potassium nitrate is an example of "a salt", while sodium chloride is "salt".

In horticulture, organic refers to plants raised according to certain agreed upon practices. In chemistry, an organic compound is one whose molecular structure is based on certain arrangements of carbon atoms. Some inorganic compounds (e.g. calcium carbonate and carbon dioxide) contain carbon but all organic compounds have carbon atoms.

Jim

Then I looked up average precipitation in New York and it's in the neighborhood of 50 inches a year.

50 inches of water stacked up over 1 square foot would weight 260.42 lbs. That means you would be getting about .00031 lbs. of nitrogen per sq. ft. over the coarse of an entire year. To put it into more common terms, about 0.31 lbs. per 1000 sq. ft., or 13.5 lbs per acre.

Everything being middle of the road, that's probably about a tenth or so of the annual nitrogen requirement. But remember, that's at the high end of the nitrate in rain graph. I didn't look up anything for ammonium but my guess is that it's probably not a whole heck of a lot.

In regards to environmental and human health concerns, I'm not your guy. Maybe Toxcrusader can chime in there.

(grumble grumble proofread grumble....)

You can avoid all the decimal shuffling by going straight to ppm/10,000. It's just a conversion factor that allows you to skip a few steps, which makes it one of those handy numbers to keep in your "tool box".