ProCrop

Role of Nitrogen and Deficiency Symptoms

Plants absorb nitrogen as either ammonium (NH₄) ions, or as nitrate (NO₃) ions, however nitrate is the predominant form. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. Proteins can be structural, or they can be specialized workhorses called enzymes. Enzymes help reduce the energy barriers which keep many chemical processes from happening randomly in a plant. There are enzymes which help breakdown certain compounds and some which synthesize other compounds. There are specific enzymes necessary for nearly every energy requiring process and activity within a plant.

Nitrogen is also a part of the DNA molecule, so it fills a very important role in cell division and reproduction. The chlorophyll molecule also contains nitrogen. Chlorophyll is the light energy receptor which begins the process we call photosynthesis; the process which turns light energy into chemical energy in the plant, so essential for life as we know it. Nitrogen deficiencies appear in crops as a yellowing of older plant tissue and general stunting of plants. Small grains will have fewer tillers.

When soil nitrate levels are high, plants can accumulate nitrates in certain tissues above what is needed at that stage of growth. A shortage of nitrogen will cause the plant to mobilize extra nitrate stored in older tissue and send it to younger, developing tissue. The plant nitrate concentration can therefore be a diagnostic tool of the nitrogen health of the plant. Deficiencies can be verified using plant tissue nitrate testing or total nitrogen analysis.

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