What are the three types of nitrogen fertilizer most commonly sold?

The three types of nitrogen fertilizer that are most commonly sold include inorganic, natural organic, and synthetic organic types. Inorganic fertilizers consist of synthetic nutrients that are immediately available to plants and are typically manufactured from chemical processes. This type includes ammonium nitrate and urea, which are widely used due to their efficiency in delivering nutrients quickly.

Natural organic fertilizers are derived from organic sources such as plant or animal materials, providing a more gradual release of nutrients, which can enhance soil health and structure over time. They contribute not only nitrogen but also other nutrients and organic matter to the soil.

Synthetic organic fertilizers encompass those that combine both organic materials and synthetic processes to release nutrients in a controlled manner, often designed to provide immediate and long-lasting benefits. These are increasingly popular due to their ability to cater to specific soil and plant needs while contributing to sustainable agricultural practices.

The other options do not represent the most commonly sold types of nitrogen fertilizers accurately. For instance, while liquid and foliar fertilizers can be effective, they are not classified as primary types but rather as methods of application. Similarly, terms like slow-release and granular are more about the form and delivery method rather than distinct categories of nitrogen sources.