Nitrogen is an integral part of all plant proteins. Thus the nutritive value of the food we eat is largely dependent on the availability of N for crop growth. It is required in greater quantities by crops than any of the other essential nutrients, with the exception of K in some high-yielding crops. Most soil N comes from organic matter, which releases N slowly, the rate being controlled by factors such as temperature, moisture, and texture.
Symptom Description — Adequate N produces a dark green color in leaves, caused by a high level of chlorophyll. As a mobile nutrient in plants, deficiency symptoms appear first on older leaves as light green to yellow foliage, and then develop on younger plant parts as the conditions becomes more serve. Other symptoms include: stunted, spindly plants, less tillering in small grains, low protein content … in seed and vegetative parts, fewer leaves. Nitrogen deficient plants will mature early, with significantly reduced yield and quality.
Phosphorus is a vital component in the process of plants converting the sun’s energy into food, feed, and fiber. Phosphorus plays a key role in photosynthesis, the metabolism of sugars, energy storage and transfer, cell division, cell enlargement, and transfer of genetic information. Phosphorus promotes early root formation and growth, as well as early shoot growth. Soil provides very small amounts of plant available P and this supply must be continually replenished from minerals and organic matter.Symptom Description — The first sign of a P shortage is an overall stunted plant. Leaf shapes may be distorted and tissue may be dark green in color. With severe deficiency, dead areas may develop on leaves, fruit, and stems. Older leaves are affected before younger ones because of the redistribution of P in the plant. Some plants, such as corn, may display a purple or reddish color on the lower leaves and stems. This condition is associated with accumulation of sugars in P-deficient plants, especially during times of low temperature.
Potassium, unlike other nutrients, K does not form compounds in plants, but remains free to ‘regulate’ many essential processes … including enzyme activation, photosynthesis, water use efficiency, starch formation, and protein synthesis. Agronomic crops contain about the same amounts of N and K, but K content of many high-yielding crops is even higher than that of N. Most soils contain large amounts of K, but only a small portion is available to plants over a growing season.Symptom Description — One of the most common K deficiency symptoms is scorching or firing along leaf margins. Since K is mobile in the plant, deficiency symptoms appear on older leaves first. Potassium-deficient plants grow slowly and develop poor root systems. Stalks are weak and lodging is common. Seed and fruit are small and shriveled; crops show lower resistance to disease and moisture stress. Plants deficient in K are sensitive to disease infestation, and have poor fruit yield and quality.
Magnesium activates more enzyme systems than any other nutrient and serves as a component of chlorophyll. Magnesium availability is often related to soil pH as its supply to plants decreases in both low and high pH soils. Although soils supply varying amounts of Mg naturally, soil reserves are depleted in many areas due to continued cropping without Mg-containing fertilizers or dolomitic limestone.Symptom Description — Since Mg is a mobile nutrient in plants, deficiency appears first on older leaves as yellowing or interveinal chlorosis. Increased severity of the deficiency can cause the symptoms to appear on younger leaf tissue with the development of necrotic symptoms when the deficiency is very severe. Leaves may become brittle or thin, and cup or curve upwards. Tips of leaves may become reddish-purple in cases of severe deficiency.
Sulphur is required in the plant for the formation of amino acids and proteins, and is essential to photosynthesis. Sulphur is supplied from organic matter and minerals, but it is often present in insufficient quantities and is available at inopportune times for the needs of high yielding crops. Sulphur has become an increasing limitation to cropping due to expanding yields.Continued use of high analysis fertilizers with little or no S, and reduced atmospheric deposition in rainfall has also lowered S input into cropping systems. Sulphur deficiency is often related to sandy soil texture, low organic matter, high rainfall, or irrigation. Some regions have lowered indigenous S supply due to organic matter losses resulting from rapid mineralization and soil erosion.
Symptom Description — Sulphur deficiency can sometimes be confused with N deficiency. Deficient plants are light yellow green in color with the yellowing initially manifested in the younger leaves as S is immobile in the plant. Entire plants can appear yellow-green in color, and fruits are light green and can lack succulence.
Calcium contributes to soil fertility by maintaining a favorable soil pH, which in turn is essential for microbial activity as crop residues are converted to organic matter and nutrients are made plant-available. Soil structure and water holding capacity are also improved with adequate Ca. Soil acidity can restrict crop growth due to increased presence of harmful concentrations of other elements such as Fe, Al, and Mn.Calcium deficiencies are most likely to occur on acid, sandy soils from which available Ca has been leached, and on strongly acid peat and muck soils where total soil Ca is low.
Symptom Description — As an immobile nutrient in plants, Ca deficiency appears as browning and die back of growing tips of roots and leaves. Leaves curl and margins turn brown with newly emerging leaves sticking together at the margins, leaving expanded leaves shredded on their edges. Fruit yield and quality will be reduced with high incidence of blossom-end rot and internal fruit decay.
Boron is essential for growth and development of new cells in the new growth areas. Seed development, cell wall formation, flowering, nodule formation, and developing fruit all depend on adequate B. Organic matter is the most important soil source of B and hot (or cold), dry weather can often slow decomposition at the soil surface, which reduces the release of B to crops. Dry weather also reduces root activity another cause of temporary B deficiency that can disappear as soils receive rainfall.Coarse-textured soils are typically low in minerals that contain B and are susceptible to B leaching.
Symptom Description — Boron is immobile in the plant and deficiency symptoms appear as abnormal growth on the youngest leaves and growing points with apical growing points eventually becoming stunted and dead. Some crop-specific B deficiency symptoms include: crooked stem in celery, hollow heart in peanut, corky core in apple, rosetting (terminal bud dieback) in alfalfa and cotton, and heart rot in sugar beet.
Manganese functions primarily as part of plant enzyme systems. It has a role in several metabolic reactions, including the conversion of nitrate-N to a form the plant can use. It plays a direct role in photosynthesis by aiding chlorophyll synthesis. Deficiencies often occur on high organic matter soils with neutral to alkaline pH and on those soils that are naturally low in Mn.Symptom Description — Manganese is immobile in the plant, so its deficiency appears as reduced or stunted growth with visual interveinal chlorosis on younger leaves. Cereals can develop gray spots on their lower leaves, and legumes can develop necrotic areas on their cotyledons. Soybeans and potatoes commonly show interveinal chlorosis on the upper leaves, while veins remain green. Leaves become pale green first, then pale yellow. Then, as the deficiency becomes more severe, brown, dead areas appear.
Iron is a catalyst to chlorophyll formation and acts as an oxygen carrier in photosynthesis. It is essential to protein synthesis, plant respiratory enzyme systems, and energy transfer. Iron deficiencies are not uncommon in many areas soils due to conditions or treatments (pH >7.0, low organic matter, cold-wet conditions, over-liming, high P fertilization) that can decrease its plant availability and induce a deficiency.Symptom Description — Iron deficiency typically first appears as interveinal chlorosis of younger leaves due to its immobile nature in plants, and as the severity of the deficiency increases, chlorosis spreads to older leaves. Severe deficiency may turn the entire plant yellow-to-bleached white. This deficiency might be overshadowed by another nutrient deficiency or nutrient imbalance. Disease, insect infestation, or herbicide damage can be incorrectly diagnosed as Fe deficiency.
Copper is a key element component of chlorophyll playing a central role in photosynthesis. Soil deficiencies are often associated with high organic matter soils, peats, and mucks since Cu is held more tightly by organic matter, thus making it less available for root uptake.Symptom Description — Copper deficiency may not be as easy to identify as other micronutrients; however, Cu does not move in the plant so it appears first in younger growth. Often young growth is reduced, stunted, or distorted. In trees, Cu deficiency may cause white tip or bleaching of younger leaves and summer dieback.
Zinc was one of the first micronutrients recognized as essential for plants. It plays a key role in many enzyme systems in plants. It controls the production of important growth regulators that influence new growth and development, thus one of the first indications of Zn deficiency is the presence of stunted plants resulting from a shortage of growth regulators.Symptom Description — Zinc deficiency appears as a chlorosis in the interveinal areas of new leaves, producing a banding appearance. Leaf and plant growth become stunted with increasing severity of the deficiency and leaves eventually die and fall off the plant. At branch terminals of fruit and nut trees, rosetting occurs with considerable dieback of the branches.
Molybdenum is needed by the plant in the synthesis and activation of nitrate reductase, an enzyme which reduces nitrate to ammonium in the plant. It is also required for symbiotic fixation of N within legume root nodules and for the conversion of inorganic P to organic forms in the plant. Unlike other micronutrients, Mo availability in the soil increases with higher soil pH. Sandy soils are more likely to be deficient in Mo.Heavy P fertilization can increase Mo uptake by plants from the soil, while S fertilization reduces Mo uptake and can induce a Mo deficiency.
Symptom Description — Molybdenum deficiency symptoms frequently resemble N deficiency. Older and middle leaves become chlorotic first, and in some instances, leaf margins are rolled and growth and flower formation is restricted.
Nickel was long considered as non-essential or toxic, but work on a variety of crops reveals it to be directly related to plant health. The essential metalloenzyme, urease, contains Ni, which is involved in symbiotic N fixation. Sprays with Ni salts are also effective against rust infection in cereals. Nickel deficiency can either be a result of low availability in soil, or could be induced by several factors, including: high contents of Ca, Mg, Cu, or Zn;availability decreases with excessive application of lime, when pH is raised above 6.5; high soil P limits availability either in the soil or within the plant itself; or nematodes can damage the root system and lead to severe deficiency.
Symptom Description — Nickel deficiency can lead to the accumulation of urea, which causes necrotic spots on the leaves. Pecan and other crops can show peculiar ‘mouse-ear’ symptoms where tips of affected young leaves have dark spots and are rounded, resembling the ear of a mouse. Cereals show interveinal chlorosis in young leaves and stunted foliage.
Chloride is involved in many critical reactions in the plant including the chemical breakdown of water in the presence of sunlight, activation of several enzymes, and cation (K, Ca, Mg) transportation. Research has shown its effect on controlling water loss and plant moisture stress, as well as fungal infections to the roots, leaves, stalks, and plant heads. Chloride is mobile in soil, is easily leached, and is removed early from minerals by weathering processes.Symptom Description — Chloride deficiency appears as chlorosis of the younger leaves and wilting of the plant. Chloride deficiency has especially been related to a number of cereal leaf diseases.
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