A definition and explanation of nitrogen and photosynthesis.

Gallon JR and Hamadi AF (1984) Studies on the effects of oxygen on acetylene reduction (nitrogen fixation) in Gloeothece sp. ATCC 27152. Journal of General Microbiology 130: 495–503.

Nitrogen is involved in some ofthose reactions, but they are not photosynthesis.

Immobilization occurs when decomposing organic matter contains low amounts of nitrogen. Thus, immobilization occurs if the source of organic matter has a high C:N ratio. Microorganisms, who also need nitrogen to live, scavenge the soil for nitrogen when plant residues contain inadequate amounts of nitrogen. As inorganic ammonium and nitrate are incorporated into the cells of living microorganisms, the total N levels in the soil are reduced. Immobilization can ultimately result in nitrogen deficiencies.

All of the above are important parts of photosynthesis.

Wyatt JT and Silvey JKG (1969) Nitrogen fixation by Gloeocapsa. Science 165: 908–909.

That should be "during growth", not "during photosynthesis"> Plants get theirs [nitrogen] by assimilating those compounds> from their environment and using them by way of photo synthesis> to make new body tissues.

The Photosynthesis Cycle | HowStuffWorks - Science

It has been estimated that nitrogen fixation in the nodules of clover roots or other leguminous plants may consume as much as 20% of the total photosynthate.

The Earth's atmosphere is mostly composed of nitrogen

However, these bacteria can make only a small contribution to the nitrogen nutrition of the plant, because nitrogen-fixation is an energy-expensive process, and large amounts of organic nutrients are not continuously available to microbes in the rhizosphere.

Oxygen makes up just 21 percent of the air we breathe

The processes of mineralization and immobilization are constantly occurring simultaneously. As organic matter decomposes, inorganic nitrogen will be released into the soil. As both plants and microorganisms grow, they utilize the nitrogen in the soil. Once plants and microorganisms die, they decompose and release inorganic nitrogen to the soil through mineralization.

Acta Agriculturae Scandinavica, Section B — Soil & …

For example, Azospirillum species have been shown to fix nitrogen when growing in the root zone (rhizosphere) or tropical grasses, and even of maize plants in field conditions.

Nitrogen - University of Hawaii

When nitrogen is immobilized in the soil, there may be little nitrogen available for crop growth. As a result, plants can suffer from nitrogen deficiency and develop a yellow coloration. This is the reason why organic materials with a high C:N ratios, such as grass clippings and grain stover, are usually composted before they are incorporated into the soil or planting. This allows time for soil microorganisms to decompose the materials and begin to release nitrogen and other nutrients back into the soil

Photosynthesis occurs at high rates when there is sufficient nitrogen

At temperatures over 40oC enzymes involved in the process are increasingly destroyed, so photosynthesis slows down and eventually stops because the photosynthesis enzymes are destroyed.