what is nitrogen fixation?

Nitrogen fixation is any process of combining atmospheric nitrogen with other elements, either by chemical means or by bacterial action: used chiefly in the preparation of fertilizers, industrial products, etc.

In the nitrogen cycle this process as performed by certain bacteria found in the nodules of leguminous plants, which make the resulting nitrogenous compounds available to their host plants.

Denitrification is the loss or removal of nitrogen or nitrogen compounds.

In the nitrogen cycle this is to reduce (nitrates) to nitrites, ammonia, and free nitrogen, as in soil by microorganisms.

Nitrogen fixation refers to the changing of molecular nitrogen to molecules that animals and plants can use. Most plants get nitrogen in the form of nitrate in the soil, although some bacteria have a symbiotic relationship with plants and can fixate atmospheric nitrogen into ammonium ions with an enzyme.

Nitrogen fixation is the conversion of atmospheric nitrogen gas, by bacteria, into ammonia and nitrates.

Denitrification is takes nitrates and nitrites and makes nitrogen gas -- the opposite of nitrogen fixation.

Nitrogen fixation refers to the ability of some organisms (most notably legumes) to process environment nitrogen (from the atmosphere or from fertilizers) into amino acids. Most animals lack the ability to synthesize amino acids directly from their components -- they must ingest the fundamental amino acids by eating plants that have already performed this synthesis.