What is nitrification?

Nitrification is a critical process in the nitrogen cycle where ammonia, which can be toxic to plants at high concentrations, is converted into nitrate, a form of nitrogen that plants can readily uptake. This two-step process involves specific bacteria; first, ammonia is oxidized to nitrite by ammonia-oxidizing bacteria, followed by the oxidation of nitrite to nitrate by nitrite-oxidizing bacteria. The resulting nitrates are then available for plant use, facilitating growth and contributing to ecosystem productivity. This transformation is essential for maintaining soil health and fertility, as it helps regulate nitrogen availability.

The other answer choices refer to different biological processes: the conversion of phosphorus to plants pertains to phosphorus cycling, nitrogen fixation involves the conversion of atmospheric nitrogen into ammonia by certain bacteria, and the breakdown of organic materials is related to decomposition processes rather than the specific conversion of ammonia to nitrate.