Essential Tree Nutrients
Nitrogen forms many thousands of organic compounds. Most are derived from ammonia, hydrogen cyanide, cyanogens, and nitrous or nitric acid. Amines, Amino acids and amides are closely related to ammonia.
Nitrogen is taken up by plants primarily as nitrate (N03-) or ammonium (NH4+)
ion. Plants can utilize both of these forms of nitrogen in their growth process. Most of the nitrogen taken up in the nitrate form. There are two basic reasons for this. First, nitrate nitrogen is mobile in the soil and moves with soil water to plant roots where uptake can occur. Ammoniacal nitrogen, on the other hand, is bound too the surfaces of soil particles and cannot move to the roots. Secondly, all forms of nitrogen added to soils are changed to nitrates by soil organisms under proper conditions of temperature, aeration, moisture, etc.
Nitrogen is used by trees to synthesize amino acids, which in turn form proteins. The protoplasm of all living cells contain protein. Nitrogen is required by trees in utilizing other vital compounds such as chlorophyll, nucleic acids and enzymes.
Soil test for nitrogen have not proven useful in determining tree needs. Tree growth and performance best determine nitrogen requirements.
When too much nitrogen is added to the soil, it induces a carbohydrate deficiency and reduces bacterial populations. Carbohydrates are the sugar,
(carbon, hydrogen, oxygen),
energy source for bacterial populations to survive. Excessive nitrogen also increases the activity of the existing potassium, and requires and increases in potassium requirements. Bacteria are most abundant at a soil carbon to nitrogen ratio 30- 1. Added nitrogen induces a sugar deficiency that reduces bacterial competition to fungi root diseases and nematodes.
Phosphorus is absorbed by plants as H2PO4-,HP04--,
depending on soil pH. Most of the total soil phosphorus is tied up chemically in compounds of limited solubility. Phosphorus is present in all living cells. In neutral to alkaline soils, Calcium phosphate is formed while in acid soils; iron and aluminum phosphates are produced. As levels of dissolved aluminum increases, a chemical reaction occurs with phosphorus compounds, making them insoluble and unavailable to plants. If dissolved aluminum levels become too high, toxic levels are reached and plants die.
Phosphorus is utilized by trees as an integral element of nucleic acids
(DNA and RNA). It is used in the storage and transfer of energy through energy-rich linkages (APT and ADP). Phosphorus stimulates early growth and root formation. Phosphorus in important because it is a catalyzing agent that induces metabolic reactions. It hastens maturity and promotes seed production. It also helps in the formation of all sugars, oils and starched. It helps in the transformation of solar energy into chemical energy, and in tree maturation. It is beneficial in the tree ability to resist stress. Phosphorus supplement is requires in limited amounts for canopy growth, limited root growth and growth in cold weather.
Several factors influence the availability of phosphorus to the tree. Soil pH influences the ionic character of phosphorus. At low pH, phosphorus, principally in the H2P04 forms. In intermediate soil pH levels, H2P04 is predominant and at higher values P304 is present. Trees can absorb all these forms, but this ionic nature of phosphorus also influences the way in binds to soil colliods. Anions (-) are strongly attached to and absorbed by soil particles, phosphates, at low soil pH, can form insoluble and unavailable salts with iron and aluminum cations (+). (cat-eye-ons). In soils with increased calcium and a high pH, CaC03
can greatly reduce the trees available phosphate. Organic matter contains large amounts of the total soil phosphate but trees do not readily absorb these unless there is first and enzymatic cleavage of the phosphate bond. This cleavage is achieved by enzyme phosphatase which is produced by microorganisms.
Trees absorb it more than any other element, except for nitrogen and in some cases, calcium. Potassium is taken up in the form of potassium ions
It is not synthesized into compounds as with nitrogen and phosphorus but tends to remain in ionic form within cells and tissues. With excessive nitrogen levels, potassium becomes busier and thus increases the demand.
Potassium is essential for translocation of sugars and starch formation. Potassium is believed important for maintaining water turgor in leaves and for functioning in the opening and closing of the stomata by guard cells.
Potassium encourages root growth and increases resistance to disease. It produces larger, more uniformly distributed xylem vessels throughout the root system, strengthens the vascular tissue and increases cell thickness.
Potassium occurs in primary minerals and is unavailable, unless there is an abundant microbial
population present. Potassium is mobile in plant tissue and is a high producer of carbohydrates as starch.
Potassium is directly involved in:
1) The synthesis of carbohydrates, proteins, oils and certain organic acids, and the acceleration of certain enzymatic action.
2) The reductase reduction of nitrates which are fundamental for the synthesis of protein and increases photosynthetic activity under low light conditions.
3) It facilitates in the transport of carbohydrates and cellular division in the tree.
4) It regulates the
nitrogen absorption by the tree and increases the resistance to diseases.
As the potassium levels declines, the manganese levels increases to a dangerously high amount in the tree. Potassium is the tree cellular liquid antifreeze system because it remains in the liquid, increases the salt level and decreases the liquid freezing point.
Hydrogen is a major element in plant growth, being the basis for all life as part of the
DNA molecule. There is very little hydrogen found in the atmosphere as it continuously escapes into space. Hydrogen combines directly with most lighter and with many of the heavier elements. It is present in all living matter in the form of compounds in which is combined with carbon and other elements.
Oxygen is a major element in plant growth, being the basis for all life as part of the DNA molecule.
It is very reactive and capable of combining with most of the other elements. It is a component of thousands of organic compounds, many of which are essential to plant growth. In what is known as photosynthesis, plants utilize available
C02 in the presence of sunlight, from both the soil and the atmosphere, assimilating the carbon element and releasing the free oxygen back into the atmosphere.
Vegetation collects carbon dioxide from the air, releases the oxygen
(02) and returns the (C)
to the earth.
All photosynthetic forms can reduce atmospheric C02 but not all can use C02 as their sole source of carbon. In the non-sulfur purple bacteria, organic substances such as acetate act as hydrogen donors for C02 reduction. In contrast, other microbes, such as nitrifying bacteria utilize inorganic substances exclusively and must therefore use atmospheric C02
as their only carbon source
Most microbial forms oxidize organic material, which serve not as substrates in energy yielding reactions but also as sources of carbon for nutrition. The range of organic compounds from which carbon is extracted by organisms is endless. Microbes as a group are especially versatile in this respect, in fact, for every naturally occurring organic material; there is a microbe capable of decomposing it.
Carbon is the one element required in largest amounts by organisms and is a common constituent of all organic matter. It is virtually involved in all life processes, as it is part of the DNA Molecule. As the number one building block for all life, it is rarely mentioned as a plant nutrient. Carbon is absorbed through the leaves directly from the air as carbon dioxide (C02).
The lack of soil organic carbon is a sure sign of a lack of organic matter in the form of humus, which is food for bacteria and soil based microbes. There are more than a million known carbon compounds many thousands of which are vital to organic and life processes. Carbon leaves Earth’s soils into the atmosphere as C02 in a constant cycle known and the Carbon Cycle.
Carbohydrates are among the most readily available sources of carbon for microorganisms. Monosaccharides. (Simple sugars) are widely used but alcohols, such as mannitol and glycerol are good sources too, especially for fungi and actinomycetes. Amino acids are readily used as carbon sources by most microorganisms while some can utilize fatty acids. Hydrocarbons, (oils) can serve as a carbon source for a few bacteria of the genus corynebacterium, mycobacterium and pseudomoas.
Utilization of compounds such as lignin is quite extensive under aerobic
conditions, but when oxygen is limited such compounds are not decomposed. Instead they accumulate, for example, as peat or coal. The major lignin decomposers are fungi, pseudomonas and actinomycetes. Almost all-free oxygen in the earth’s atmosphere is due to photosynthesis.
CALCIUM (Ca) Secondary Nutrient
Calcium is absorbed by plants as the calcium ion
(Ca++). It is an essential part of cell wall structure and must be present for the formation of new cells. Calcium is not mobile in plants. Young plant absorption and retention of other ions such as magnesium. Calcium is a second messenger in the signal by which stomatal guard cells respond to external stimuli. (potassium is the prime guard cell chemical for functioning the opening and closing of the stomata).
The mechanism responsible for plant discrimination between
K+ and Na+ depends on the present of Ca+. +.
A small amount of calcium in a foliar solution increases the plant uptake of potassium by as much 150% by changing cell membrane permeability. An excess of potassium or magnesium can reduce calcium uptake. Maintenance of the plant tissue cell wall structure depends on calcium cross linkages. The brown discoloration that occurs in most calcium deficient tissue could be the result of increased leakage of phenolic compounds into the cytoplasm. Oxidation of some of the enzymes would then occur. The biological roles of calcium in the growth and development of plants: Calcium’s effect on plant membranes. Its effect of cell wall structure. Its role in enzyme activities and its It’s interaction with phytohormones.
Iron is an essential element to plants and is found combined with other elements in hundreds of minerals. In trees, the sulfate compound is an essential source of iron, which utilizes it in the formation of chlorophyll in plant cells. It serves as an activator for biochemical processes such as plant respiration, photosynthesis, and symbiotic nitrogen fixation. Deficiencies can be induced by high levels of manganese or lime content in soils. Iron is taken up by plant either in the ferrous
(Fe ++) or (Fe+++)
Molybdenum is a relatively rare element that is not found in its free form in nature. Its primary benefit to plants is as a catalyst in assisting bacteria in the fixation and utilization of nitrogen. Plants cannot transform nitrate of nitrogen into amino acids or it cannot fix atmospheric nitrogen unless molybdenum is present. Plants uptake molybdenum in either a sodium molybdate or molybdenum trioxide form.
Sodium is essential to all life and is the most common alkali metal. Sodium dose not occur free in nature, due to its’ great reactivity. It easily unites with oxygen and other elements, but is extremely active. The most familiar sodium compound is sodium chloride
or common salt. Excess amounts can be damaging to all biological systems. It is present in most soils and aids in the biological process carried out by the soil microorganisms.
Magnesium serves as a catalyst for enzyme activities in carbohydrate metabolism. It dose not occur in mature uncombined. Magnesium is an essential element in plants and is non-toxic. Plants uptake is in the form of magnesium ion
The chlorophyll molecule contains magnesium and is therefore Essential for photosynthesis, Magnesium serves as an activator for many plant enzymes required in the growth process. It is mobile in plants and can be readily translocated from older to younger tissue under conditions of deficiency.
Manganese participates as an activator for enzymes in growth processes in plants, where it helps break down carbohydrates. It may be essential for the utilization of vitamin
B and assist iron in chlorophyll formation. Manganese helps in the metabolic reduction of nitrates in green plants and algae. High levels of manganese may induce iron deficiency and is generally toxic to plants in excessive levels. Manganese uptake is primarily in the form of the ion
Sulfur is essential to all life as a component of fats, organic fluids. It is non-toxic in its elemental form as well as its sulfate compound, and plant uptake is in the form of sulfate ions
Sulfur may also be absorbed from the air through the leaves in areas where the atmosphere has been enriched with sulfur compounds from industrial or volcanic sources. Sulfur is a constituent of two amino acids (mathionine and cysteine)
and is therefore essential for protein synthesis and is present in oil compounds
responsible for plant odor. It helps in chlorophyll formation.
Boron is taken up by plants as borate and is necessary for the growth of land plants. It functions in plants in the differentiation of meristem cells. It aids in the use and regulation of other elements as in the production of sugar and carbohydrates and nut production. It is not considered a poison, but excessive amounts tend to act as an unselective herbicide, as toxicity symptoms appear as necrotic lesions on leaves, crinkling of margins on tips of leaves. With boron deficiency, cells may continue to divide but structural components are not differentiated. “Brown Heart” and “Dry Rot” are among the disorders due to boron deficiency. Boron is non-mobile in plants and a constant supply is necessary at all growing points. Deficiency is first found in the youngest tissues of the plant.
Free chlorine is a minor constituent of volcanic gas and it is essential to all life. In plants, it aids in metabolism, as it is required in the photosynthetic reaction of plants. Deficiency is not seen in the field due to its universal presents in nature.
It occurs naturally in many elemental compounds and in natural waters and plants. Cobalt is an essential trace element, as part of vitamin B-12.
In plants, cobalt has recently been shown to be required to fix nitrogen but not when fixed nitrogen is present. Cobalt in small amounts has been found to be effective in correcting mineral deficiencies, and aids in growth process of root development in the soils. As with most trace elements, excessive amounts can be toxic.
Copper is trace element found both in free state, and in mineral compounds. In the sulfate form, Copper is a catalyzing element in plant metabolic reactions and an activator of several enzymes in plants; it also plays a role in vitamin A production. Vitamin A deficiency interferes with protein syntheses and subsequent reproductive growth. It aids in root metabolism. Plants uptake is in the form of ions
Excessive amounts of Copper are toxic.
Zinc is an essential trace element as is fairly rare. Zinc is an essential component of several enzyme systems in plants, including the transformation of carbohydrates. It regulates the consumption of sugars, and it controls the synthesis of indole-acetic acid, an important growth regulator. Terminal growth is affected first when zinc is deficient. Zinc is absorbed by plants as the zinc ion (Zn++).
Excessive amounts are toxic as in certain compounds; it is used as a herbicide.
This group includes elements that are used as nutrients by only a limited number of plant species. When high concentrations of an element, not commonly found in most plants, is seen in a particular species, it raises the possibility that the element is essential for that species. The plant may use these for non-nutritional purposes. It is thought that species where these elements are present may use them for protection against invading bacteria. For example barium is found in Brazil nuts; aluminum in tea; chromium, nickel and cobalt in gramineae; silicon in rice and cucumbers.
Is not recognized as a plant nutrient, although is found in certain plant species. Barium and all its mineral compounds that are soluble are toxic, so in is not known why some plant species survive with level of barium present.
Is a rare element and combines readily with many elements. With the exception of a few plant species, bromine has no known biological role. It is a toxin and sometime used in control of nematodes and other invading microbes in the soil. It is not known why certain plant species contain significant levels of bromine.
In its elemental form occurs sparingly. The biological role of nickel is uncertain as is toxic, depending on its compound form. It is not known why certain species pf plants contain higher levels of nickel.
Usually occurs combined but is also found uncombined in conjunction with free sulfur. In excess, it is toxic, depending on the compounds. Selenium can replace sulfur in certain sulfur amino acids and in certain compounds are potentially poisonous.
Is an element that is found combined and in plants, vanadium is an essential trace element, but in limited quantities, as some of its compounds are toxic. Recent studies have indicated that vanadium has a tendency to impersonate phosphorus. Plant roots apparently cannot differentiate the two. In soil testing vanadium has been found to be the source of inaccurate phosphorus testing and new procedures includes test for vanadium.
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