Which process involves the release of plant-available nitrogen from organic matter?

Nitrogen mineralization is the essential process that transforms organic nitrogen from plant and animal residues into inorganic forms that plants can readily utilize. This occurs through the activity of microorganisms in the soil, which decompose organic matter, breaking it down into simpler compounds. During this process, organic matter, such as compost or decomposed plant material, is converted into ammonium (NH4+) and eventually into nitrate (NO3-), both of which are key sources of nitrogen that plants need for growth and development.

The process is vital for maintaining soil fertility and ensuring that nitrogen is available to support the physiological and biochemical functions of plants. In environments where organic matter is plentiful, such as in well-managed agricultural systems, nitrogen mineralization contributes significantly to the nitrogen supply for crops. It is influenced by various factors, including temperature, moisture, and the type of organic materials present.

The other processes mentioned, such as nitrogen fixation, involve the conversion of atmospheric nitrogen into forms usable by plants, nitrogen volatilization refers to the loss of nitrogen to the atmosphere, and nitrogen leaching involves the downward movement of nitrogen in water through the soil, none of which relate directly to the release of plant-available nitrogen from organic matter like nitrogen mineralization does.