Compare the rate of human contributions to nitrogen fixation with the natural rate.

Nitrogen fixation is the modification of nitrogen present in the atmosphere into a combined form (e.g ammonia) via chemical and some biological action (microbes like soil rhizobia).

Human processes, e.g fertilizers production and fossil fuels consumption, have majorly affected to a high amount the level of fixed nitrogen in the Earth's ecosystems. It is believed that the level of nitrogen fixed by human process will be much more than that fixed via microbial processes involving diazotrophs such bacteria as Azotobacter and archaea as effected by enzyme nitrogenases.

The rate amounting from nitrogen fixation is believed to be 140 teragrams (Tg) of nitrogen per year (1 teragram is equivalent to 1 million metric tons). This amount is very small when viewed to the level at which human factors or means of contribution increases nitrogen amount to the environment.

correct answer: biotic and abiotic limitations

carrying capacity is defined as the total number of an organism who can be supported in a given area within the natural resources limit and without harming or degrading the natural, economic or the cultural environment present for the future generations.

carrying capacity is determined by the limiting factors, which are known to affect the natural resources available. it may include water, nutrients, minerals, space, light etc.

explanation:

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a fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.[1] the age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years.[2] fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.[3] other commonly used derivatives include kerosene and propane. fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of almost pure carbon, like anthracite coal. methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.

the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust over millions of years was first introduced by andreas libavius "in his 1597 alchemia [alchymia]" and later by mikhail lomonosov "as early as 1757 and certainly by 1763".[4] the first use of the term "fossil fuel" was by the german chemist caspar neumann, in english translation in 1759.[5]

in 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy consumption in the world.[6] non-fossil sources in 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.[7] world energy consumption was growing at about 2.3% per year. in 2015 about 18% of worldwide consumption was from renewable sources.[8]