The Importance of Nitrogen in Plant Nutrition

Of all the essential nutrients, nitrogen (N) is the nutrient that normally produces the greatest yield response in crop plants, promoting rapid vegetative growth and giving the plant a healthy green colour. And yet it is also the nutrient that most often limits crop growth. Choosing the right nitrogen fertiliser will reward your crops with better growth, and reward growers with better returns.

Role of Nitrogen

Nitrogen is an important component of many essential structural, genetic, and metabolic compounds in plant cells. It is also an elementary constituent of numerous important organic compounds including amino acids, proteins, nucleic acids, enzymes, and the chlorophyll molecule. It is clear to see why it is essential to ensure crops have access to sufficient nitrogen.

Plant roots take up nitrogen in its inorganic forms, nitrate (NO₃^–) and ammonium (NH₄⁺) ions. Once inside the plant, NO₃ is reduced to the NH₂ form and is assimilated to form the organic compounds.

Nitrogen is not recommended for legume crops such as soybean, since they manufacture their own nitrogen supply. Nitrogen-fixing soil organisms (rhizobium) associated with the roots of legumes capture atmospheric nitrogen and make it available to the plant.

Symptoms of Nitrogen Deficiency

Plants lacking nitrogen have very slow growth and look weak and stunted. Older leaves have a light green or yellow colour. As nitrogen is mobile in the plant and moves to where it is needed, these older and lower leaves are always first to show symptoms of deficiency.