Which form of nitrogen is unavailable to plants?

Which form of nitrogen is unavailable to plants?

• A. Inorganic nitrogen
• B. Organic nitrogen
• C. Ammonium nitrogen
• D. Nitrate nitrogen

Answer: (B)

Organic nitrogen is considered unavailable to plants in its natural state because it is contained within complex organic molecules in plant and animal residues, as well as in soil organic matter. Plants cannot directly take up organic nitrogen; first, it must be decomposed by soil microorganisms into inorganic forms, such as ammonium or nitrate, which are readily absorbable by plant roots. In contrast, inorganic nitrogen, ammonium nitrogen, and nitrate nitrogen are forms readily available to plants. These forms are soluble and can be directly taken up by the plant roots and utilized for growth and development. Understanding the various forms of nitrogen and their availability to plants is crucial for effective nutrient management in agricultural practices.

Organic nitrogen is considered unavailable to plants in its natural state because it is contained within complex organic molecules in plant and animal residues, as well as in soil organic matter. Plants cannot directly take up organic nitrogen; first, it must be decomposed by soil microorganisms into inorganic forms, such as ammonium or nitrate, which are readily absorbable by plant roots.

In contrast, inorganic nitrogen, ammonium nitrogen, and nitrate nitrogen are forms readily available to plants. These forms are soluble and can be directly taken up by the plant roots and utilized for growth and development. Understanding the various forms of nitrogen and their availability to plants is crucial for effective nutrient management in agricultural practices.