Nitrogen is the element that soils require in greatest amounts. It is the most important-yet the most often deficient-element in plant growth worldwide. Nitrogen is highly volatile, so it escapes to the air, and leaches away in run-off water. Nitrogen should be applied more often than most nutrients, especially if the organic content of the soil is low.
Nitrogen is essential to the photosynthesis and healthy cell growth and reproduction. It is vital in producing chlorophyll (which gives the leaves good green color) and amino acids. It also promotes shoot and leaf growth.
Nitrogen deficiency in corn causes yellowing of older leaves, progressing upward. In young corn plants, nitrogen deficiency causes the whole plant to be pale yellowish green with spindly stalks.