Nitrogen is an important component of many essential structural, genetic and metabolic compounds in plant cells; it is also an elementary constituent of numerous organic compounds of general importance, including amino acids, proteins, nucleic acids, enzymes, and the chlorophyll molecule.
Of all the essential nutrients, nitrogen is the one that is most often limiting for crop growth. Nitrogen is the nutrient whose changes normally produce the greatest yield response in crop plants, promoting rapid vegetative growth and giving the plant a healthy green color.
Roots take up N 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 addition is not recommended for legume crops such as soybean, since they benefit from the fixing of atmospheric nitrogen by soil microorganisms associated with their roots (rhizobium).
Deficiency symptoms: Very slow growth; weak and stunted plants. Older leaves have a light green to yellow color. Since N is mobile in the plant, the bottom leaves are always affected first.
Fertilizer sources: ICL Fertilizers' granular fertilizers GNPK and GNP contain nitrogen in their formulation, with N content up to 11%, such as GNPK 5.8-30-16.1, GNP 8-40-0 and a whole range of other formulas.