There are a handful of ways to express the relationship between plants and nitrogen. However, the best way to describe their relationship is to call it symbiosis. Interaction between two different organisms living in close physical association, typically to the advantage of both. Plants need nitrogen more than any other element. Plants need to get nitrogen from the soil, where it has already been fixed by bacteria and archaea. Bacteria and archaea in the soil and in the roots of some plants have the ability to convert molecular nitrogen from the air (N2) to ammonia (NH3), thereby breaking the tough triple bond of molecular nitrogen.1 Nitrogen is a vital component of chlorophyll, which is the compound by which plants use the sun's sunlight energy to produce sugars from carbon dioxide and water. (i.e. photosynthesis) It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die. Nitrogen contains 3-4% of Nitrogen in their above-ground tissues.2 Nitrogen is also the primary building block for plant protoplasm. Protoplasm is the translucent substance that is the living matter in cells.3 Because plants use so much nitrogen, adequate nitrogen levels in soil result in exceptional plant growth.4 Without a rich nitrogen presence in soil, plants may experience nitrogen deficiency, which affects photosynthesis and the health of the plant.5 Lack of nitrogen shows up as general yellowing (chlorosis) of the plant. The leading factor in nitrogen deficiency is an excess of carbon in the soil, which nitrogen can break down, but that leaves less for the plants.6 Without nitrogen, plants couldn't get energy. Nitrogen is the fuel that makes plants go. It's used to synthesize amino acids, proteins, chlorophyll, nucleic acids, and enzymes.7

Plants and Nitrogen

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Management factors, such as N-rate, N source, N placement method, the timing of application, irrigation management, residue management, crop type, etc. all can affect how efficiently N is used by crops and the number of N losses. Nitrogen management on sandy soils is important because of the high potential for leaching losses. Selecting an appropriate N rate is the primary management consideration. However, nitrogen source, timing N application close to plant uptake, and method of application such as injecting N to avoid losses are also important. Management measures that increase organic matter and avoid compaction are also important to stabilize crop N supply, increase aeration (the introduction of air into a material), and limit N losses due to denitrification occurring in saturated soils.8 Without nitrogen, plants won’t have the right “stuff” to be healthy. This is because nitrogen is involved in a variety of plant processes, including photosynthesis. Nitrogen also plays a role in the growth of tissues and cells found within the plant, as well as the formation of chlorophyll. Chlorophyll helps plants receive energy from the light which is very important in the functionality and survival of the plant. Nitrogen also aids in the formation of protein which is involved in many biochemical reactions within plants. And last, but certainly not least, nitrogen plays an active role in the growth and reproduction of cells which, again, is a pretty big deal.9

As many people know, a plant is mainly multicellular organisms, predominantly photosynthetic eukaryotes of the kingdom Plantae; it is a living thing that grows in the earth and has a stem, leaves, and roots. Nitrogen is a chemical element with an atomic number of 7.10 In an article published by Frontiersin, the author states, “It is also essential to life: a key building block of DNA, which determines our genetics, is essential to plant growth, and therefore necessary for the food we grow”.11 In addition, Nitrogen is vital to plant growth because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide. It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.12

You can click here to watch a short video talking about the different purposes of nitrogen.13

Click here for a video discussing the process of the nitrogen cycle in the soil and how the plant uses it.14