What does immobilization refer to in nutrient management?

Immobilization in nutrient management specifically refers to the process where inorganic nitrogen is converted into organic nitrogen. This process occurs when soil microorganisms take up inorganic forms of nitrogen, such as ammonium and nitrate, and incorporate them into their biomass. As these microorganisms grow and decompose, the nitrogen they have assimilated becomes part of the organic matter in the soil.

This conversion effectively makes nitrogen temporarily unavailable to plants, as the organic forms of nitrogen must first be mineralized back into inorganic forms before being usable by plants again. Understanding immobilization is crucial in nutrient management because it highlights the dynamics of nutrient availability in the soil, thus influencing fertilizer application timing and rates to optimize plant growth and minimize nutrient loss.