18

According to the recent paper in Nature Geoscience: Nitrogen speciation in upper mantle fluids and the origin of Earth's nitrogen-rich atmosphere, $N_2$ originates from regions of the Earth where plates are converging. Venus and Mars lack plate tectonics and therefore lack $N_2$ in their atmospheres. In other regions of Earth upper mantle, and in Venus and ...


11

Both of them. The composition of the atmosphere, crust, mantle, core and bulk earth are all notably different. The atmosphere is composed of ~78% nitrogen and ~21% oxygen, with small amounts of other gases. The bulk composition of the earth by weight is mostly, iron, oxygen, silicon and magnesium, in that order, with all the other elements making up only ...


8

For Earth, Titan and Venus, I think there are continuing processes that are providing $\ce{N2}$ to the atmosphere of these planets. Concerning the Earth, there is the well documented Nitrogen cycle based on flora. There are also other significant sources for nitrogen from inorganic processes. Deep crust/mantle core sources for nitrogen: Nitrogen ...


6

Nitrogen is volatile in most of its forms here on Earth. It is fairly non-reactive with most materials that make up the solid part of Earth, and it is very stable in the presence of solar radiation in the atmosphere. Even though, nitrogen is 4 times more abundant than oxygen in the atmosphere, we must also consider the relative abundances of nitrogen and ...


5

First, don't take that graph too literally, it is just a cartoon version and isn't quantitatively correct. The USSR heavily subsidized fertilizer until 1988. When they ended the subsidy, fertilizer prices increased to market prices and use of fertilizer decreased. Fertilizer use decreased further after the USSR fell a couple years later. Fertilizer ...


5

I went to do a bit of research on this, and think that you can get a satisfactory answer just from the relevant wikipedia articles. Here are some select quotes: Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Nitrogen fixation has the chemical ...


4

There are a number of factors that went/are going into the population explosion, food is only one vaccination and antibiotics are a big factor as well. within food fertilizer is again only one of many factors. Better crop strains, mechanized and better farming techniques, soil science, pesticides, refrigeration, and a dozen other factors contributed. Keep ...


4

NO2 uptake by plants It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [Breuninger et al, 2013]. Currently, it is assumed that NO2 is taken up through stomata of plant leaves when the atmospheric NO2 concentrations are above a certain threshold. However, when the atmospheric NO2 concentrations are below this ...


4

A huge factor affecting a planet's atmospheric composition is the planet's escape velocity. From Wikipedia, we have a table of escape velocities, and here are some sample figures: Earth: 11.2 km/s Mars: 5.0 km/s Jupiter: 59.6 km/s Pluto: 1.2 km/s The molecules of an atmospheric gas all fly around with different velocities. Turns out, these velocities ...


3

These two links were the sources I used when researching this question: "Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains" http://co.water.usgs.gov/publications/non-usgs/Nanus_2012.pdf "Approaches for estimating critical loads of nitrogen and sulfur deposition for Forest Ecosystems of U.S. Federal Lands" http://...


3

The reason Earth has so much nitrogen is because it is non reactive and builds up. The origin of the nitrogen is covered in previous answers. Also, Venus has as much nitrogen in its atmosphere as Earth, but it is a much smaller percentage due to the large amount of CO2. Here is a nice graph showing what gases can exist in a planetary atmosphere based on ...


3

The two major sources of atmospheric nitrogen are volcanoes and bottom-dwelling denitrifying bacteria, who produce it from nitrate ion dissolved in seawater. If anyone knows the relative importance of these two sources, I'd very much appreciate knowing. Tx.


3

You probably mean 50kgN/ha, which sounds like a plausible number for fertilizer application. I don't know what you are doing exactly, but you need to know how much surface area your soil sample represents. If you do planting tests, it will be simply the surface of your bed. Then it's just mulitplying the surface area by 50kgN/ha (mind the units!). Now you ...


2

Two things to think about: Nitrous oxide is extremely scarce in the atmosphere, less than 1 ppm. Compare with carbon dioxide that (unfortunately) is now greater than 400 ppm. Also consider the lifetime of the gases in the atmosphere: nitrous oxide has a much shorter lifetime than carbon dioxide. If we'd stop emitting greenhouse gases now, nitrous oxide ...


2

There isn't enough nitrous oxide in the atmosphere to make a major contribution to global warming, which in some ways is a pity, because we'd all bee in a much jollier mood if there was (N2O is sometimes known as laughing gas). It also depletes the ozone layer if it gets up that high, though depleting ozone at ground level, where it is harmful, is a good ...


2

There are several aspects to be considered in this apparent difference. First, your quote from Wikipedia describes the change in productivity but does not account for other factors that have lead to productivity increase such as changed farming practices (larger, more sophisticated farm equipment, improved use of weather and soil data, etc.) changes to crop ...


2

"How can this be reconciled?" In two words: silicon dioxide :-) Yes, that's simplistic, but reflects the fact that virtually all the oxygen occurs in chemical combinations with other elements, not as free oxygen. The same is true for other elements in the crust & mantle.


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