There are 90 or more plant nutrients, 17 of which are essential to plant health. Nickle was the newest to the list in the 1980’s. 3 are considered Basic Macronutrients or atmospheric elements and are usually available in sufficient quantities through air, water and soil. Note: Nitrogen is also considered an atmospheric element, as air consists of 78% nitrogen (N2). However, atmospheric nitrogen is not in a form that plants can use: nitrate (NO3–) or ammonia (NH4+) and as such is not usually available in sufficient quantities.
Like all living things plants require oxygen to survive. Oxygen is essential for the process of photosynthesis where by the plant, in the presence of sunlight, takes in carbon dioxide and water and creates oxygen and energy in the form of sugar. Oxygen is required for ATP (adenosine 5′-triphosphate) production, which is the main molecule involved with the storing and transferring of energy in cells. So with no oxygen the plant has no energy and begins to wither and die. Oxygen is also involved with the process of respiration where by the plant, in the absence of light, takes in oxygen and combines it with the sugars resulting in the release of carbon dioxide.
Carbon is essential to all life on earth. We are all made of carbon and must consume carbon to create energy for our growth and existence. Plants take in carbon dioxide and water and create oxygen and energy in the form of sugar. The plants use the sugar for their growth. Humans, animals insects and soil microbes, etc. consume the plants and derive our energy from the sugars in the plants.
“Hydrogen is the most widely distributed element in the world, accounting for more than 75% of the mass of the universe” (Zeng, J., Ye, Z. & Sun, X (2014)).
Plants acquire their hydrogen predominantly through water (H2O) and is the 3rd key player in the process of photosynthesis and respiration. Hydrogen is required for the manufacturing of food energy for the plant and thus it’s growth. Some researchers have found that hydrogen can also contribute to stress resistance such as salinity, drought, cold and heavy metals. (Zeng, J., Ye, Z. & Sun, X (2014)). They have additionally linked hydrogen to seed germination, regulation of flowering time, improvement of crop resistance to disease and pests, reducing fertilizer use and crop preservation.
Of the 14 mineral nutrients the 3 you will be most familiar with are: Nitrogen (N), Phosphorus (P) and Potassium (K)
They are collectively classified primary macronutrients. (Macronutrients being nutrients that are consumed in larger quantities while micronutrients are those consumed in smaller quantities). These 3 plant nutrients are essential for plant growth, health and for the process of photosynthesis. Plants use larger amounts of these 3 nutrients than any other nutrient and as such the soil can easily become depleted of them, requiring fertilizers (either natural or synthetic) to add the nutrients back into the soil. The numbers you see represented on fertilizer packages and containers correspond to these 3 nutrients. The first number representing Nitrogen the second number representing Phosphorus and the third number Potassium. Note: nitrogen can be both an atmospheric element or mineral.
Nitrogen is essential for photosynthesis and promotes a deep green colour and lush growth. Besides being a major component of chlorophyll, nitrogen is also a major component of amino acids, the building blocks of proteins. Nitrogen stimulates early spring growth and is essential to overall root, stem and leaf growth.
Phosphorus is essential to seed development, disease resistance and plant growth. It is necessary for producing sugar during photo-synthesis and it encourages root growth, flower and fruit production. It also strengthens stems, helps in resistance to pests and diseases and increases the rate of vegetable crop maturity.
Potassium helps to regulate a plants metabolism and contributes to early growth, stem strength, hardiness, draught resistance, vigour, good flower colour and disease resistance. It is essential for the proper development of root crops and the regulating of water within the plant. In fruit bearing plants potassium improves the flavour, vitamin content, size and colour of fruit.
The second group of soil nutrients are classified secondary MACRONUTRIENTS. They include: Calcium (Ca), Magnesium (Mg) and Sulfur (S)
While each of these soil nutrients are essential to your plants health, there are usually enough of them in the soil so fertilization is not always necessary. If you suspect a nutrient deficiency you may want to have to have your soil tested before you begin adding these nutrients.
Calcium (Ca) is essential not only for healthy plants but also for balancing soil chemistry. Calcium helps to unlock other nutrients and any imbalances with this nutrient can cause imbalances with other nutrients. One of the primary roles of calcium in plant health is the key role it plays in cell walls. Calcium increases cell wall strength and thickness (Dr. G. W. Easterwood, 2002). It also serves to regulate cell permeability and is required for cell division and growth (University of Guelph, n.d.). Other important roles and health benefits of calcium include:
- Disease reduction (Dr. G. W. Easterwood, 2002).
- Root development; short roots are often observed on calcium deficient plants (Carl Schwartzkopf, 1972).
- Reduces the effects of heat stress by improving stomatal function (A & L Canada Laboratories, 2005).
- Increases the efficiency of surface applied urea fertilizer by reducing ammonia volatilization (loss of nitrogen to the atmosphere as a gas) (Dr. G. W. Easterwood, 2002).
- Assists with nutrient uptake (A & L Canada Laboratories , 2005)
- Important for nitrogen metabolism (K.A. Kelling and E.E. Schulte, 2004).
- Increases salt tolerance in many plant species (Bio-Gro, n.d.).
- Saline and sodic soil management.
- Improves a soils structure.
For a more complete discussion on Calcium visit my blog post Calcium It’s Role in Soil and Plant Health.
Magnesium is essential for photosynthesis and the movement of sugars within a plant. Magnesium also helps to activate many plant enzymes needed for growth.
Promotes root growth and seed production, and helps to maintain a dark green colour; it helps with vigorous plant growth and resistance to cold; and it is also used to acidify soil. Sulfur is slowly released from organic matter by microbial activity.
The remaining 8 soil nutrients are classified MICRONUTRIENTS. They include: Boron (B), Copper (Cu), Chloride (CI), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Zinc (Zn), Nickle (Ni)
Even though these nutrients are used in very small amounts they are non-the-less all essential for plant growth.
Boron (B) plays a role in cellular activities, root growth, seed formation and the movement of sugars within the plant. Boron is also “essential for pollen germination and growth of the pollen tube” (R. Uchida 2000).
Copper (Cu) plays a role in photosynthesis and is essential in several enzyme systems. Copper increases the sugar content in plants and intensifies the flavour and colour in fruits, vegetables and flowers. Copper also plays a role in seed production and formation, and is essential for plant respiration.
Chloride (Cl) plays an essential role in cellular hydration, water management within the plant and the opening and closing of stomata, thus is essential for photosynthesis. It also plays a role in the suppression of some plant diseases. In saline soils it is toxic. It has long been believed to be antagonistic to nitrate (NO3–) but some research now shows chloride may actually improve nitrogen use efficiency (Rosales M et al 2020).
Iron (Fe) is essential for chlorophyll production and plays a role in plant respiration, photosynthesis and nitrogen fixation in legumes. Iron plays a critical role in metabolic processes such as DNA synthesis.
Manganese (Mn) is essential for photosynthesis and respiration. Manganese helps to break down nitrogen, phosphorus and calcium making them more readily available to the plant. Additionally manganese activates many enzyme systems some of which help to protect plants against some soil born diseases, some fungal leaf diseases, and some environmental stressors like draught, winter cold, salt damage and ozone damage. It also assists with pollen germination and pollen tube growth (Bloodnick E. 2021).
Molybdenum (Mo) plays the essential role in converting nitrates into ammonia within the plant, (the form that can be taken up by the plant). Molybdenum is also required by some microorganisms, namely rhizobia bacteria, that have a symbiotic relationship with legumes. These bacteria help to fix atmospheric nitrogen in legumes. Molybdenum also assists in the conversion of inorganic forms of phosphorus into organic forms that the plant can take up. Note: it was once believed that nitrogen fixation could not occur unless their was a sufficient amount of molybdenum in the soil, but science has since discovered that nature has a backup plan. “Nitrogen fixation can be carried out by the metal vanadium in ecosystems where the primary catalyst molybdenum is scarce” (Princeton University, 2019).
Zinc (Zn) is involved in the enzymatic system and plant metabolism. It plays a role in RNA and protein synthesis and is necessary for chlorophyll production and carbohydrate formation. Additionally it is involved with growth hormone production, regulating plant growth and stem elongation. Zinc also helps plants to withstand cold temperatures (Bloodnick E. 2021).
Nickle, the newest nutrient to join the essential nutrients list in 1987 (Patrick H. Brown, et al., 1987). Although it was not recognized by the American Association of Plant Food Control officials until 2004 (Guodong Liu et al. 2020). Nickel is essential of nitrogen metabolism in plants and the biological fixation of atmospheric nitrogen in legumes. It is involved in plant growth, senescence, metabolism, iron uptake, and disease resistance (Patrick H. Brown, et al., 1987).
Photo Credit: This photo/slide was created by the author.
Last updated on Dec. 26, 2021
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Updated: August 22, 2022
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