There are several ways to immediately increase usable forms of nitrogen in the soil:
1. Organic matter amendment: Adding organic materials such as compost, manure, or cover crops to the soil can quickly increase the nitrogen content. These materials break down over time, releasing nitrogen into the soil.
2. Nitrogen fertilizers: Applying synthetic or organic nitrogen fertilizers provides an immediate source of nitrogen for plants. Examples include ammonium sulfate, urea, or fish emulsion.
3. Legume cover crops: Planting leguminous cover crops like clover, vetch, or peas can increase nitrogen levels due to their ability to fix nitrogen from the atmosphere into the soil.
4. Animal urine or blood meal: Sprinkling urine or applying blood meal from animals high in nitrogen content directly to the soil increases usable forms of nitrogen instantly.
5. Nitrogen-fixing bacteria inoculants: Adding specific strains of nitrogen-fixing bacteria to the soil can facilitate nitrogen fixation from the atmosphere, making it available to plants.
It's important to note that while these methods provide immediate nitrogen availability, long-term soil health and fertility should be supported through sustainable agricultural practices such as crop rotation, organic matter replenishment, and minimizing the use of synthetic fertilizers.