Sources of Nitrogen to the Soil

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Natural ecosystems receive their soil nitrogen through ______ fixation and atmospheric deposition.

biological

Agricultural ecosystems receive additional nitrogen through ______ addition.

fertilizer

Only a few species of bacteria and cyanobacteria are capable of ______ fixation.

nitrogen

Lightning was the major source of soil nitrogen until recent times when the burning of ______ fuels became a major source of atmospheric deposition.

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Nitrogen oxides come from a variety of combustion sources that use ______ fuels.

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Crop rotation with legumes such as soybeans or alfalfa is practiced to supplement soil ______.

nitrogen Signup and view all the answers

______ species of bacteria can convert ammonium (NH4+) into nitrites (NO2-)

Several Signup and view all the answers

Plants can take in either ammonium (NH4+) or nitrates (NO3-) and make ______ or nucleic acids

amino acids Signup and view all the answers

Decomposers convert organic nitrogen (CHON) into ______ and ammonium (NH4+)

ammonia Signup and view all the answers

A broad range of bacterial species can convert nitrites, nitrates and nitrous oxides into molecular ______ (N2)

nitrogen Signup and view all the answers

Molecular nitrogen in the air can be fixed into ammonia by a few species of ______

prokaryotes Signup and view all the answers

Producers can take up NH4- and to N03- use it to make ______

CHON Signup and view all the answers

All but a small portion of the earth’s carbon is tied up in ______ rocks; but the portion that circulates is what sustains life.

sedimentary Signup and view all the answers

The active pool of carbon is estimated to be around 40,000 ______.

gigatons Signup and view all the answers

Of active carbon, 93.2% is found in the ______.

ocean Signup and view all the answers

99.4% of exchangeable N is found in the ______.

atmosphere Signup and view all the answers

Among the fossil fuel sources, power plants and automobiles are important sources of atmospheric nitrogen ______ in the US.

deposition Signup and view all the answers

Investigations of native plant and natural ecosystem responses to nitrogen deposition and global warming will be a focus of ______.

study Signup and view all the answers