6 Reasons Why agriculture ought to Be Your New Hobby

Reasons For agriculture as Hobby

1. It's primarily free medical aid.

Think about it -- absorbing the fat-soluble vitamin, obtaining out your anger by breaking apart the soil and resting within the peaceful presence of your plant babies. Is there anything better? it is an excellent activity for folks that got to raise their spirits or simply wish to make their own natural sanctuary.

2. It's sensible for your health.

While agriculture isn't associate intense activity, it will provide you with the chance to urge out there and sweat a touch, to not mention all the recent, nourishing vegetables you will have pronto available!

3. it is a good way to beautify any house.

The best reasonably beauty is usually natural beauty. I mean, have you ever SEEN plants? Nothing will match the charm and wonder of a flower, or the rise inexperienced of a thriving leaf. And, since agriculture may be done anyplace, it's excellent for drab, unused areas that require sprucing up.

4. it is a good way to avoid wasting cash.

For an equivalent value of a few of tomatoes, you'll get a packet of seeds and grow dozens of tomatoes per plant. It's crazy what number fruits or veggies one plant will manufacture. In fact, it's the most effective come back on investment I will think about.

5. It makes a distinction for the surroundings (even over you think).

Of course, a lot of plants we tend to propagate, a lot of greenhouse emission we will eliminate from the atmosphere, however on the far side that the less we tend to deem out-of-state and foreign manufacture, the fewer fossil fuels we tend to consume. It takes a staggering quantity of energy -- a lot of it unsustainable -- to industrially sow, propagate, harvest, preserve, and transport recent manufacture on the huge scale we tend to do nowadays. Compare that to the near-invisible carbon footprint of a curtilage garden, and it's clear that the planet would be more contented if a lot of individuals relied on their own gardens for manufacture.

6. you may ne'er get bored.

There's continuously one thing unaccustomed kill your garden. every season brings its own tasks and opportunities: beginning seeds in late winter and early spring, sowing in late spring and early summer, weeding, watering, and fertilizing in summer, gathering in late summer and fall, and beginning everywhere once more by coming up with over the winter and you'll even alter into activities like plant breeding or competition.
it's conjointly amazingly artistic.
Sure, the care of plants is stock-still in science, however, there are endless ways in which to create it associate art. produce an ornamental fairy garden, or grow a cover from sunflowers and vine. Play with the associate infinite combination of shapes and colors for gorgeous beds, lovely bouquets, and cookery creations.

>BASIC SOIL COMPONENTS

A soil is simply a porous medium consisting of minerals, water, gases, organic matter, and microorganisms.

The traditional definition is:

Soil is a dynamic natural body having properties derived from the combined effects of climate and biotic activities, as modified by topography, acting on parent materials over time.

There are five basic components of soil that, when present in the proper amounts, are the backbone of all terrestrial plant ecosystems:
• Mineral: The largest component of soil is the mineral portion, which makes up approximately 45% to 49% of the volume. Soil minerals are derived from two principal mineral types. Primary minerals, such as those found in sand and silt, are those soil materials that are similar to the parent material from which they formed. They are often round or irregular in shape. Secondary minerals, on the other hand, result from the weathering of the primary minerals, which releases important ions and forms more stable mineral forms such as silicate clay. Clays have a large surface area, which is important for soil chemistry and water-holding capacity. Additionally, negative and neutral charges found around soil minerals influences the soil's ability to retain important nutrients, such as cations, contributing to a soils cation exchange capacity (CEC).
The texture of a soil is based on the percentage of sand, silt, and clay found in that soil. The identification of sand, silt, and clay are made based on size. The following is used in the United States: Sand 0.05 – 2.00 mm in diameter
Silt 0.002 - 0.05 mm in diameter
Clay < 0.002 mm in diameter
The U.S. Department of Agriculture Soil Texture Triangle is used to determine the overall texture of soil based on the percentage of sand, silt, and clay.
The texture of a soil can be determined from its sand, silt, and clay content using a textural triangle. The triangle above (Figure 2) is the one created by the U.S. Department of Agriculture's Natural Resources Conservation Service and is primarily used in the United States. Percent clay in this triangle is read on the lefthand side of the triangle, the percent silt is read on the righthand side, and the percent sand is on the bottom. For example, if a soil contains 20% clay, 40% sand, and 40% silt (total = 100%), then it is a loam.
• Water: Water is the second basic component of soil. Water can make up approximately 2% to 50% of the soil volume. Water is important for transporting nutrients to growing plants and soil organisms and for facilitating both biological and chemical decomposition. Soil water availability is the capacity of a particular soil to hold water that is available for plant use.
The capacity of a soil to hold water is largely dependent on soil texture. The more small particles in soils, the more water the soil can retain. Thus, clay soils having the greatest water-holding capacity and sands the least. Additionally, organic matter also influences the water-holding capacity of soils because of organic matter's high affinity for water. The higher the percentage of organic material in soil, the higher the soil's water-holding capacity.
The point where water is held microscopically with too much energy for a plant to extract is called the “wilting coefficient” or “permanent wilting point.” When water is bound so tightly to soil particles, it is not available for most plants to extract, which limits the amount of water available for plant use. Although clay can hold the most water of all soil textures, very fine micropores on clay surfaces hold water so tightly that plants have great difficulty extracting all of it. Thus, loams and silt loams are considered some of the most productive soil textures because they hold large quantities of water that is available for plants to use.
• Organic matter: Organic matter is the next basic component that is found in soils at levels of approximately 1% to 5%. Organic matter is derived from dead plants and animals and as such has a high capacity to hold onto and/or provide the essential elements and water for plant growth. Soils that are high in organic matter also have a high CEC and are, therefore, generally some of the most productive for plant growth. Organic matter also has a very high "plant available" water-holding capacity, which can enhance the growth potential of soils with poor water-holding capacity such as sand. Thus, the percent of decomposed organic matter in or on soils is often used as an indicator of a productive and fertile soil. Over time, however, prolonged decomposition of organic materials can lead it to become unavailable for plant use, creating what are known as recalcitrant carbon stores in soils.
• Gases: Gases or air is the next basic component of soil. Because air can occupy the same spaces as water, it can make up approximately 2% to 50% of the soil volume. Oxygen is essential for root and microbe respiration, which helps support plant growth. Carbon dioxide and nitrogen also are important for belowground plant functions such as for nitrogen-fixing bacteria. If soils remain waterlogged (where gas is displaced by excess water), it can prevent root gas exchange leading to plant death, which is a common concern after floods.
• Microorganisms: Microorganisms are the final basic element of soils, and they are found in the soil in very high numbers but make up much less than 1% of the soil volume. A common estimate is that one thimble full of topsoil may hold more than 20,000 microbial organisms. The largest of the these organisms are earthworms and nematodes and the smallest are bacteria, actinomycetes, algae, and fungi. Microorganisms are the primary decomposers of raw organic matter. Decomposers consume organic matter, water, and air to recycle raw organic matter into humus, which is rich in readily available plant nutrients.

Other specialized microorganisms such as nitrogen-fixing bacteria have symbiotic relationships with plants that allow plants to extract this essential nutrient. Such "nitrogen-fixing" plants are a major source of soil nitrogen and are essential for soil development over time. Mycorrhizae are fungal complexes that form mutalistic relationships with plant roots. The fungus grows into a plant's root, where the plant provides the fungus with sugar and, in return, the fungus provides the plant root with water and access to nutrients in the soil through its intricate web of hyphae spread throughout the soil matrix. Without microbes, a soil is essentially dead and can be limited in supporting plant growth.

>Essential Components Of Soil

Plants need several inputs in order to survive and thrive. Water, of course, is essential, as it is for all living things; a medium in which to grow; and sunlight to enable them to photosynthesize are all key. But at a smaller scale, there are three elements that are essential ingredients to healthy plant growth: potassium, nitrogen and phosphorous. Each performs a different role for the plant, and making a good balance of these elements available to their plants is one of the roles of the permaculture gardener to ensure healthy plants and a good harvest. Fortunately there are methods and techniques that gardeners can employ to increase the presence of each of the three elements in the soil.

Nitrogen:

Nitrogen, taken up by plant roots from the soil after it has been processed into a soluble form by microorganisms, is essential for plants to develop proteins. These proteins are important for the development of cells within the plant. As such, nitrogen is needed for robust plant growth, speedy development of shoots, healthy flower bud development and a good quality harvest. It is also an essential chemical in the photosynthesis process, by which plants convert sunlight into useable energy. As such, you can tell if your soil is low in nitrogen if plant leaves turn yellowish and brown at the tips (however, be advised that because plants can move nitrogen around to benefit new growth, some old leaves will go yellow anyway, even if nitrogen is not deficient.).

If you are looking to increase the amount of nitrogen in the soil of your permaculture plot, there are several organic ways of doing so. Adding composted animal manure can help, and is easy if you have livestock. Poultry manure has high levels of nitrogen, but must be composted before application to the soil to prevent plant burn. Adding used coffee ground to compost is another method. If you want to increase the nitrogen content in a site prior to planting food crops, you could consider planting a ‘green manure’ crop. This is a cover crop, such as borage, clover or alfalfa that is grown then slashed and left to rot into the soil. When you have established your garden beds, adding nitrogen fixing plants is a good idea. These leguminous species, which include peas and beans, work with a bacteria commonly found in the soil to draw nitrogen from the air and store it in their roots. Some of this nitrogen penetrates into the soil and other plants can use it.

Phosphorous:

Phosphorus plays a number of important roles in the physical development of a plant. Firstly, it is used by the plant to move energy and nutrients around itself, so that all parts of the plant remain healthy. With nitrogen, it helps in the process of photosynthesis, while it also a crucial component in the formation of nucleic acids, which help form the plant’s DNA, and so helps plants grow strong and develop solid roots. An insufficient supply of phosphorous can cause leaves to wilt or die back, stems and veins on leaves to appear purple, and poor seed and fruit development.

Adding animal meal to the soil is one of the most effective ways to increase phosphorous levels. Fish or bone meal are both viable alternatives, though you should check the source of the meal to ensure that it does not come from animals that have been treated with antibiotics, and that it originates from a sustainable source. Animal manure, particularly from horses, can also help up phosphorus levels, as can adding rock phosphate, although this will take a longer time to break down. Be careful not to elevate phosphorus levels in the soil too much as excessive levels can adversely affect beneficial fungi in the soil, and even leach into groundwater.

Potassium:

Potassium is key to ensuring all the physiological process in a plant function normally. It is an element that helps the plant activate chemical elements essential for plant growthenzymes, form sugars, and synthesize proteins. Potassium exists in two forms in the soil, one soluble and the other not. Plants can only use the soluble form of potassium, as it functions within the stomata, the cell system within the plant that uses water to cycle nutrients around all parts of the plant. Good levels of potassium help the plant use moisture efficiently, which helps prevent disease and heat damage, as well as reducing the need for the plant to be irrigated. Too little potassium in the soil will lead to leaves curling and becoming distorted. Root systems are also unlikely to develop, particularly in young plants, while stalks can appear weak and spindly.

There are several ways that the permaculture gardener can increase the amount of potassium in the soil. The first solution, and the answer to lots of soil questions, is the addition of good compost. Lots of vegetable and fruit scraps – particularly banana – will provide a boost to the potassium levels in your compost, and the good thing about adding compost to the soil, is the potassium compounds within the compost are already in a water-soluble form, meaning plants can access them immediately. Adding wood ash – the remnants after burning hardwoods, to you compost is another method for increasing potassium levels, although it can affect the pH level of the soil, so test regularly. Kelp and granite dust are alternative methods (although the latter takes a relatively long time to release its nutrients).

There are other elements that are crucial to healthy plants, and which the permaculture gardener can ensure are available by maintaining a healthy soil. Calcium, for instance, helps build strong cell walls, Magnesium is a central component in chlorophyll, the green pigment that is essential to photosynthesis, while sulfur is important in the formation of vitamins. However, nitrogen, phosphorous and potassium are the ‘big three’ – get the levels of those in the soil right, primarily by ensuring the soil has a lot of organic matter (which will have the knock-on effect of providing all the other elements needed by the plants) and you should be able to ensure a healthy garden and a bountiful harvest.

>ROLE OF PHOSPHORUS

Phosphorus aids in strong root development and bloom production.

Phosphorus is a much-needed element for plant development and growth. Each nutrient in the soil helps to satisfy one of the plant's needs; phosphorus is no different. Phosphorus aids in the development of strong, healthy roots and as such is often sold at transplanting time. Some high-phosphorus fertilizers are known as "root-stimulating" fertilizers for this reason. Phosphorus also aids in the development of seeds, buds and blooms and therefore is excellent for flowers, fruits and fruiting vegetables. Phosphorus is the middle number in the N-P-K rating, or three-digit number, on the package of fertilizer.

The Importance Of Phosphorus:

The function of phosphorus in plants is very important. It helps a plant convert other nutrients into usable building blocks with which to grow. Phosphorus is one of the main three nutrients most commonly found in fertilizers and is the “P” in the NPK balance that is listed on fertilizers. Phosphorus is essential to a plant’s growth, but what does it mean if you have high phosphorus in your soil, or a phosphorus deficiency? Keep reading to learn more about the importance of phosphorus in plant growth. Phosphorus Deficiency in the Soil How can you tell if your garden has a phosphorus deficiency? The easiest way to tell is to look at the plants. If your plants are small, are producing little or no flowers, have weak root systems or a bright green or purplish cast, you have a phosphorus deficiency. Since most plants in the garden are grown for their flowers or fruit, replacing phosphorus in the soil if it is lacking is very important. There are many chemical fertilizers that can help you with replacing phosphorus and getting a good nutrient balance in your soil. When using chemical fertilizers, you will want to look for fertilizers that have a high “P” value (the second number in the fertilizer rating N-P-K). If you would like to correct your soil’s phosphorus deficiency using organic fertilizer, try using bone meal or rock phosphate. These both can help with replacing phosphorus in the soil. Sometimes, simply adding compost to the soil can help plants be better able to take up the phosphorus that is already in the soil, so consider trying that before you add anything else. Regardless of how you go about replacing phosphorus in the soil, be sure not to overdo it. Extra phosphorus can run off into the water supply and become a major pollutant. High Phosphorus in Your Soil It’s very difficult for a plant to get too much phosphorus due to the fact that it’s difficult for plants to absorb phosphorus in the first place. There’s no understating the importance of phosphorus in plant growth. Without it, a plant simply cannot be healthy. The basic function of phosphorus makes it possible to have beautiful and abundant plants in our gardens.

Organic Phosphorus Sources:
• Several organic sources of phosphorus are commercially available. Among these is fish bonemeal or other bonemeal, made from the crushed bones of various animals. Bonemeal often has an extremely high percentage of phosphorus, from 11 percent to 18 percent, and sometimes even more. Various types of guano are also high in phosphorus. Vermicompost is high in both nitrogen and phosphorus. Vermicompost is manure that has been digested by worms. While this reduces the volume, it adds microbial diversity, a plus when amending your soil due to the increased microbial activity.

Inorganic Sources:
• Rock phosphate is another source of phosphorus and is mined within the United States. Rock phosphate has a high percentage of phosphorus, typically 8 percent to 20 percent. Nurseries and big-box stores also sell root-stimulating fertilizers high in phosphorus, as well as fertilizers with names like "Bud and Bloom Booster."

Types of Fertilizers:

Either liquid and dry fertilizers are can be added to soil to boost the phosphorus content. Plants will absorb the phosphorus from both fertilizer types, so you can choose the one that suits you best. Granular fertilizers are composed of small granules that are typically raked into the soil around the plant and then watered in. Liquid fertilizers are often mixed with water and poured around the drip line of the plant.

Similar to most things, too much of a good thing applies to phosphorus. Too much phosphorus can greatly damage the plant by making it difficult for the plant to absorb various other nutrients. Phosphorus is also a main suspect in various environmental problems, especially those concerning bodies of water. It can promote the growth of dangerous algae to the point of inflicting illness and even death to animals. Because of this, only add phosphorus when needed. Having a soil test performed on your soil to see which nutrients are lacking is one way to know how much phosphorus to add.

>ROLE OF POTASSIUM IN PLANTS

Potassium is an essential plant nutrient and is required in large amounts for proper growth and reproduction of plants. Potassium is considered second only to nitrogen, when it comes to nutrients needed by plants, and is commonly considered as the “quality nutrient.”

Potassium (K) is the third of the three primary nutrients required by plants along with nitrogen (N) and phosphorus (P). When you read the label on a bag of fertilizer (e.g.: 20-10-20), the third number indicates the percentage of potassium by weight in the fertilizer. Technically, this number refers to K2O, which is 83% elemental K by weight. Water-soluble fertilizers are typically formulated using potassium nitrate or potassium sulfate as the source of potassium. In cases where sulfate is lacking in a fertilization program, potassium sulfate is a useful material. However, potassium chloride could also be used, but should be avoided since the added chloride is not needed by plants and contributes unwanted salts.

It affects the plant shape, size, color, taste and other measurements attributed to healthy produce.
Plants absorb potassium in its ionic form, K+.

Function/ROLES OF POTASSIUM IN PLANTS:

Potassium has many different roles in plants:
• In Photosynthesis, potassium regulates the opening and closing of stomata, and therefore regulates CO2 uptake.
• Potassium triggers activation of enzymes and is essential for production of Adenosine Triphosphate (ATP). ATP is an important energy source for many chemical processes taking place in plant issues.
• Potassium plays a major role in the regulation of water in plants (osmo-regulation). Both uptake of water through plant roots and its loss through the stomata are affected by potassium.
• Known to improve drought resistance.
• Protein and starch synthesis in plants require potassium as well. Potassium is essential at almost every step of the protein synthesis. In starch synthesis, the enzyme responsible for the process is activated by potassium.
• Unlike nitrogen and phosphorus, potassium is not used in the structural synthesis of bio-chemically important molecules. Potassium is found within the plant cell solution and is used for maintaining the turgor pressure of the cell (meaning it keeps the plant from wilting). In addition, potassium plays a role in the proper functioning of stomata (cells located on the bottom of the leaf that open and close to allow water vapor and waste gases to escape) and acts as an enzyme activator.
• Activation of enzymes: potassium has an important role in the activation of many growth related enzymes in plants.
• The main role of potassium is to provide the ionic environment for metabolic processes in the cytosol, and as such functions as a regulator of various processes including growth regulation.[2] Plants require potassium ions (K+) for protein synthesis and for the opening and closing of stomata, which is regulated by proton pumps to make surrounding guard cells either turgid or flaccid. A deficiency of potassium ions can impair a plant's ability to maintain these processes. Potassium also functions in other physiological processes such as photosynthesis, protein synthesis, activation of some enzymes, phloem solute transport of photoassimilates into source organs, and maintenance of cation:anion balance in the cytosol and vacuole.

POTASSSIUM DEFICIENCY IN PLANTS:

In soilless growing media, potassium availability is not significantly influenced by pH. Potassium deficiency symptoms are most likely to appear when insufficient potassium is provided by fertigation. There are also situations where an induced potassium deficiency arises if calcium, magnesium or sodium levels are too high, but it is rare if a crop is fed with normal potassium rates.

Potassium deficiency might cause abnormalities in plants, usually the symptoms are growth related.

Potassium defficiency symptoms:
• Typical symptoms of potassium deficiency in plants include brown scorching and curling of leaf tips as well as chlorosis (yellowing) between leaf veins. Purple spots may also appear on the leaf undersides. Plant growth, root development, and seed and fruit development are usually reduced in potassium-deficient plants. Often, potassium deficiency symptoms first appear on older (lower) leaves because potassium is a mobile nutrient, meaning that a plant can allocate potassium to younger leaves when it is K deficient.[3] Deficient plants may be more prone to frost damage and disease, and their symptoms can often be confused with wind scorch or drought. The deficiency is most common in several important fruit and vegetable crops; notably potatoes, brassicas, tomatoes, apples, currants, gooseberries, and raspberries.
• Cholrosis: scorching of plant leaves, with yellowing of the margins of the leaf. This is one of the first symptoms of Potassium deficiency. Symptoms appear on middle and lower leaves.
• Slow or Stunted growth: as potassium is an important growth catalyst in plants, potassium deficient plants will have slower or stunted growth.
• Poor resistance to temperature changes and to drought: Poor potassium uptake will result in less water circulation in the plant. This will make the plant more susceptible to drought and temperature changes.
• Defoliation: left unattended, potassium deficiency in plants results in plants losing their leaves sooner than they should. This process might become even faster if the plant is exposed to drought or high temperatures. Leaves turn yellow, then brown and eventually fall off one by one.

Other symptoms of Potassium deficiency:
• Poor resistance to pests
• Weak and unhealthy roots
• Uneven ripening of fruits
Leaf tissue analysis shows that potassium levels are often close to those of nitrogen at around 3 to 5% on a dry weight basis. Plants that are potassium deficient typically show symptoms such as chlorosis followed by necrosis at the tips and along the margins of leaves. Since potassium is mobile within the plant, deficiency symptoms appear on older leaves.

Potassium deficiency in Poinsettia:

“Potassium deficiency seen in poinsettias as necrotic leaf edges.”

In potatoes:

Tuber size is much reduced and crop yield is low. The leaves of the plant appear dull and are often blue-green in color with intervenal chlorosis. Leaves will also develop small, dark brown spots on the undersides and a bronzed appearance on the upper surfaces.

In brassicas:

Leaves are blue-green in color and may have a low degree of intervenal chlorosis. Scorching along the outside edges of leaves is common, and leaves are often tough in texture due to slow growth.

In tomatoes:

The stems are woody and growth is slow. Leaves are blue-green in color, and the intervenal area often fades to a pale gray color. Leaves may also have a bronzed appearance and yellow and orange patches may develop on some of the leaflets. Fruits often ripen unevenly and sometimes have green patches near the stalks.

In apples:

Leaves are scorched around the edges, and intervenal chlorosis is common. Apple fruits often have a slightly acidic or woody taste.

In gooseberries, currants, and raspberries:

Dieback of shoots and branches is common and although the plant may produce many blossom buds in the early stages of deficiency, fruit yields turn out low and the fruits are of poor quality.

Potassium deficiency and plant disease:

For many species, potassium-deficient plants are more susceptible to frost damage and certain diseases than plants with adequate potassium levels. Increased disease resistance associated with adequate potassium levels indicates that potassium has roles in providing disease resistance, and increasing the potassium levels of deficient plants have been shown to decrease the intensity of many diseases. However, increasing potassium concentration above the optimal level does not provide greater disease resistance. In agriculture, some cultivars are more efficient at K uptake due to genetic variations, and often these plants have increased disease resistance.[1] The mechanisms involved with increased host resistance and potassium include a decreased cell permeability and decreased susceptibility to tissue penetration. Silica, which is accumulated in greater quantities when adequate potassium is present, is incorporated into cell walls, strengthening the epidermal layer which functions as a physical barrier to pathogens. Potassium has also been implicated to have a role in the proper thickening of cell walls.

Proper fertilizer management can avoid potassium deficiencies and damage to crops.

Toxicity:

Potassium toxicity does not exist per se. However, excessive levels of potassium can cause antagonisms that lead to deficiencies in other nutrients such as magnesium and calcium. If this occurs, it is best to test the growing medium and plant tissue for nutrient content and adjust the fertilization program or application rate. Prevention and cure:The most widely used potassium fertilizer is potassium chloride (muriate of potash). Other inorganic potassium fertilizers include potassium nitrate, potassium sulfate, and monopotassium phosphate. Potassium-rich treatments suitable for organic farming include feeding with home-made comfrey liquid, adding seaweed meal, composted bracken, and compost rich in decayed banana peels. Wood ash also has high potassium content. Adequate moisture is necessary for effective potassium uptake; low soil water reduces K uptake by plant roots. Liming acidic soils can increase potassium retention in some soils by reducing leaching;[1] practices that increase soil organic matter can also increase potassium retention.

>ROLE OF MAGNESIUM

Magnesium is an essential plant nutrient. It has a wide range of key roles in many plant functions. One of the magnesium's well-known roles is in the photosynthesis process, as it is a building block of the Chlorophyll, which makes leaves appear green.

Magnesium is a macronutrient that is necessary to both plant growth and health. It is involved in several different processes, including photosynthesis, which nearly all living organisms are dependent on. Magnesium (Mg), along with calcium and sulfur, is one of the three secondary nutrients required by plants for normal, healthy growth. Don’t be confused by the term "secondary" as it refers to the quantity and not the importance of a nutrient. A lack of a secondary nutrient is just as detrimental to plant growth as a deficiency of any one of the three primary nutrients (nitrogen, phosphorus and potassium) or a deficiency of micronutrients (iron, manganese, boron, zinc, copper and molybdenum). Furthermore, in some plants, the tissue concentration of magnesium is comparable to that of phosphorus, a primary nutrient.

Technically, magnesium is a metallic chemical element which is vital for human and plant life. Magnesium is one of thirteen mineral nutrients that come from soil, and when dissolved in water, is absorbed through the plant’s roots. Sometimes there are not enough mineral nutrients in soil and it is necessary to fertilize in order to replenish these elements and provide additional magnesium for plants.

Magnesium is the powerhouse behind photosynthesis in plants. Without magnesium, chlorophyll cannot capture sun energy needed for photosynthesis. In short, magnesium is required to give leaves their green color. Magnesium in plants is located in the enzymes, in the heart of the chlorophyll molecule. Magnesium is also used by plants for the metabolism of carbohydrates and in the cell membrane stabilization.

MAGNESIUM POOLS IN SOILS

In soil, magnesium is present in three fractions:
• Magnesium in soil solution: Magnesium in soil solution is in equilibrium with the exchangeable magnesium and is readily available for plants.
• Exchangeable magnesium: This is the most important fraction for determining the magnesium that is available to plants. This fraction consists of the magnesium held by clay particles and organic matter. It is in equilibrium with magnesium in soil solution.
• Non-exchangeable magnesium: Consists of the magnesium that is a constituent of primary minerals in the soil. The break down process of minerals in soils is very slow; therefore, this magnesium fraction is not available to plants.

Function of magnesium:

Many enzymes in plant cells require magnesium in order to perform properly. However, the most important role of magnesium is as the central atom in the chlorophyll molecule. Chlorophyll is the pigment that gives plants their green color and carries out the process of photosynthesis. It also aids in the activation of many plant enzymes needed for growth and contributes to protein synthesis.

Where to Find magnesium:

Plants that are suffering from a lack of magnesium will display identifiable characteristics. Magnesium deficiency appears on older leaves first as they become yellow between the veins and around the edges. Purple, red or brown may also appear on the leaves. Eventually, if left unchecked, the leaf and the plant will die. Magnesium can be found in the dolomitic limestone used in most soilless growing media, but it is usually not in sufficient supply to meet the needs of plants. Water can be a source of an appreciable level of magnesium; therefore, have it tested before choosing a fertilizer. If your water does not provide at least 25 ppm magnesium, then it will need to be provided by fertilizer. Check the labels of the fertilizers you currently use, to see if they supply magnesium. If they do not, supplement with Epsom salts, chemically known as magnesium sulfate heptahydrate (MgSO4.7H2O). Another option is to use a cal-mag (calcium-magnesium containing) fertilizer, but unlike Epsom salts, cal-mag fertilizers are potentially basic and will cause the growing medium's pH to rise over time.

MAGNESIUM UPTAKE BY PLANTS:

Plants take up magnesium in its ionic form Mg+2, which is the form of dissolved magnesium in the soil solution.

The uptake of magnesium by plants is dominated by two main processes:
• Passive uptake, driven by transpiration stream.
• Diffusion – magnesium ions move from zones of high concentration to zones of lower concentration.
Therefore, the magnesium amounts that the plant can take up depend on its concentration in the soil solution and on the capacity of the soil to replenish the soil solution with magnesium.

MAGNESIUM AVAILABILITY AND UPTAKE:

Conditions such as, low soil pH, low temperatures, dry soil conditions and high levels of competing elements, such as potassium and calcium, reduce the availability of magnesium. Under such conditions, magnesium deficiency is more likely.

Effect of Soil pH on magnesium availability:
• In low-pH soils, the solubility of magnesium decreases and it becomes less available.
• Due to the large hydrated radius of the magnesium ion, the strength of its bond to the exchange sites in soil is relatively low. Acidic soils increase the tendency of magnesium to leach, because they have less exchangeable sites (lower CEC).
• In addition, in acidic soils, elements such as manganese and aluminum become more soluble and result in reduced magnesium uptake.
• Other positive-charged ions, such as potassium and ammonium may also compete with magnesium and reduce its uptake and translocation from the roots to upper plant parts. Therefore, excessive applications of these nutrients might prompt magnesium deficiency. Care should be especially taken in sandy soils, as their CEC is low and they can hold less magnesium.

MAGNESIUM DEFICIENCIES:

• The role of magnesium is vital to plant growth and health. Magnesium deficiency in plants is common where soil is not rich in organic matter or is very light.
• Heavy rains can cause a deficiency to occur by leaching magnesium out of sandy or acidic soil. In addition, if soil contains high amounts of potassium, plants may absorb this instead of magnesium, leading to a deficiency.
• Plants that are suffering from a lack of magnesium will display identifiable characteristics. Magnesium deficiency appears on older leaves first as they become yellow between the veins and around the edges. Purple, red or brown may also appear on the leaves. Eventually, if left unchecked, the leaf and the plant will die.
• Magnesium deficiency might be a significant limiting factor in crop production.
• Magnesium is mobile within the plant so deficiency symptoms appear first in older leaves. The symptoms show up as yellow leaves with green veins (i.e. interveinal chlorosis). Magnesium availability is not significantly affected by the pH of a soilless growing medium. However, it does become more available for plant uptake as the pH of the growing medium increases. Magnesium deficiency often is caused by lack of application, but it can be induced if there are high levels of calcium, potassium or sodium in the growing medium.
• Magnesium deficiency symptoms on the lower leaves of a zonal Geranium
• Magnesium deficiency, like any deficiency, leads to reduction in yield. It also leads to higher susceptibility to plant disease.

Symptoms:

Since magnesium is mobile within the plant, deficiency symptoms appear on lower and older leaves first. The first symptom is pale leaves, which then develop an interveinal chlorosis. In some plants, reddish or purple spots will appear on the leaves.

The expression of symptoms is greatly dependent on the intensity to which leaves are exposed to light. Deficient plants that are exposed to high light intensities will show more symptoms.

Toxicity:

Magnesium toxicity is very rare in greenhouse and nursery crops. High levels of magnesium can compete with plant uptake of calcium or potassium and can cause their deficiencies in plant tissue.

>ROLE OF NITROGEN IN PLANTS

Of all the essential nutrients, nitrogen is required by plants in the largest quantity and is most frequently the limiting factor in crop productivity.
Healthy plants often contain 3 to 4 percent nitrogen in their above-ground tissues. This is a much higher concentration compared to other nutrients. Carbon, hydrogen and oxygen, nutrients that don’t play a significant role in most soil fertility management programs, are the only other nutrients present in higher concentrations.

In plant tissue, the nitrogen content ranges from 1 and 6%.
Proper management of nitrogen is important because it is often the most limiting nutrient in crop production and easily lost from the soil system.

Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die. Some proteins act as structural units in plant cells while others act as enzymes, making possible many of the biochemical reactions on which life is based. Nitrogen is a component of energy-transfer compounds, such as ATP (adenosine triphosphate). ATP allows cells to conserve and use the energy released in metabolism. Finally, nitrogen is a significant component of nucleic acids such as DNA, the genetic material that allows cells (and eventually whole plants) to grow and reproduce. Without nitrogen, there would be no life as we know it.

Structure of an Amino Acid

Nitrogen is essential for crops to achieve optimum yields. A critical component of amino acids in protein, it also increases protein content of plants directly.

Soil Nitrogen:

Nitrogen is an essential element of all amino acids. Amino acids are the building blocks of proteins.

Nitrogen is also a component of nucleic acids, which form the DNA of all living things and holds the genetic code.

Nitrogen is a component of chlorophyll, which is the site of carbohydrate formation (photosynthesis). Chlorophyll is also the substance that gives plants their green color.

Photosynthesis occurs at high rates when there is sufficient nitrogen.

A plant receiving sufficient nitrogen will typically exhibit vigorous plant growth. Leaves will also develop a dark green color.

Soil nitrogen exists in three general forms:

• Organic Nitrogen compounds
• Ammonium (NH4+) ions
• Nitrate (NO3-) ions

Nitrogen Forms and Function

Forms of nitrogen available for plant uptake:

Ammonium

Nitrate

At any given time, 95 to 99 percent of the potentially available nitrogen in the soil is in organic forms, either in plant and animal residues, in the relatively stable soil organic matter, or in living soil organisms, mainly microbes such as bacteria. This nitrogen is not directly available to plants, but some can be converted to available forms by microorganisms. A very small amount of organic nitrogen may exist in soluble organic compounds, such as urea, that may be slightly available to plants.

The majority of plant-available nitrogen is in the inorganic forms NH4+ and NO3- (sometimes called mineral nitrogen). Ammonium ions bind to the soil's negatively charged cation exchange complex (CEC) and behave much like other cations in the soil. Nitrate ions do not bind to the soil solids because they carry negative charges, but exist dissolved in the soil water, or precipitated as soluble salts under dry conditions.

Natural Sources of Soil Nitrogen:

• The nitrogen in soil that might eventually be used by plants has two sources: nitrogen- containing minerals and the vast storehouse of nitrogen in the atmosphere. The nitrogen in soil minerals is released as the mineral decomposes. This process is generally quite slow, and contributes only slightly to nitrogen nutrition on most soils. On soils containing large quantities of NH4+-rich clays (either naturally occurring or developed by fixation of NH4+ added as fertilizer), however, nitrogen supplied by the mineral fraction may be significant in some years.
• Atmospheric nitrogen is a major source of nitrogen in soils. In the atmosphere, it exists in the very inert N2 form and must be converted before it becomes useful in the soil. The quantity of nitrogen added to the soil in this manner is directly related to thunderstorm activity, but most areas probably receive no more than 20 lb nitrogen/acre per year from this source.
• Bacteria such as Rhizobia that infect (nodulate) the roots of, and receive much food energy from, legume plants can fix much more nitrogen per year (some well over 100 lb nitrogen/acre). When the quantity of nitrogen fixed by Rhizobia exceeds that needed by the microbes themselves, it is released for use by the host legume plant. This is why well-nodulated legumes do not often respond to additions of nitrogen fertilizer. They are already receiving enough from the bacteria.

The Nitrogen Cycle

Nitrogen can go through many transformations in the soil. These transformations are often grouped into a system called the nitrogen cycle, which can be presented in varying degrees of complexity. The nitrogen cycle is appropriate for understanding nutrient and fertilizer management. Because microorganisms are responsible for most of these processes, they occur very slowly, if at all, when soil temperatures are below 50° F, but their rates increase rapidly as soils become warmer.

The heart of the nitrogen cycle is the conversion of inorganic to organic nitrogen, and vice versa. As microorganisms grow, they remove H4+ and NO3- from the soil’s inorganic, available nitrogen pool, converting it to organic nitrogen in a process called immobilization. When these organisms die and are decomposed by others, excess NH4+ can be released back to the inorganic pool in a process called mineralization. Nitrogen can also be mineralized when microorganisms decompose a material containing more nitrogen than they can use at one time, materials such as legume residues or manures. Immobilization and mineralization are conducted by most microorganisms, and are most rapid when soils are warm and moist, but not saturated with water. The quantity of inorganic nitrogen available for crop use often depends on the amount of mineralization occurring and the balance between mineralization and immobilization.

Ammonium ions (NH4+) not immobilized or taken up quickly by higher plants are usually converted rapidly to NO3- ions by a process called nitrification. This is a two-step process, during which bacteria called Nitrosomonas convert NH4+ to nitrite (NO2-), and then other bacteria, Nitrobacter, convert the NO2- to NO3-. This process requires a well-aerated soil and occurs rapidly enough that one usually finds mostly NO3- rather than NH4+ in soils during the growing season.

The nitrogen cycle contains several routes by which plant-available nitrogen can be lost from the soil. Nitrate-nitrogen is usually more subject to loss than is ammonium-nitrogen. Significant loss mechanisms include leaching, denitrification, volatilization and crop removal.

The nitrate form of nitrogen is so soluble that it leaches easily when excess water percolates through the soil. This can be a major loss mechanism in coarse-textured soils where water percolates freely, but is less of a problem in finer-textured, more impermeable soils, where percolation is very slow.

These latter soils tend to become saturated easily, and when microorganisms exhaust the free oxygen supply in the wet soil, some obtain it by decomposing NO3-. In this process, called denitrification, NO3- is converted to gaseous oxides of nitrogen or to N2 gas, both unavailable to plants. Denitrification can cause major losses of nitrogen when soils are warm and remain saturated for more than a few days.

Losses of NH4+ nitrogen are less common and occur mainly by volatilization. Ammonium ions are basically anhydrous ammonia (NH3) molecules with an extra hydrogen ion (H+) attached. When this extra H+ is removed from the NH4 ion by another ion such as hydroxyl (OH-), the resulting NH3 molecule can evaporate, or volatilize from the soil. This mechanism is most important in high-pH soils that contain large quantities of OH- ions.

Crop removal represents a loss because nitrogen in the harvested portions of the crop plant is removed from the field completely. The nitrogen in crop residues is recycled back into the system, and is better thought of as immobilized rather than removed. Much is eventually mineralized and may be reutilized by a crop.

Plant Nitrogen Needs and Uptake:

Plants absorb nitrogen from the soil as both NH4+ and NO3- ions, but because nitrification is so pervasive in agricultural soils, most of the nitrogen is taken up as nitrate. Nitrate moves freely toward plant roots as they absorb water. Once inside the plant, NO3- is reduced to an NH2 form and is assimilated to produce more complex compounds. Because plants require very large quantities of nitrogen, an extensive root system is essential to allowing unrestricted uptake. Plants with roots restricted by compaction may show signs of nitrogen deficiency even when adequate nitrogen is present in the soil.

Most plants take nitrogen from the soil continuously throughout their lives, and nitrogen demand usually increases as plant size increases. A plant supplied with adequate nitrogen grows rapidly and produces large amounts of succulent, green foliage. Providing adequate nitrogen allows an annual crop, such as corn, to grow to full maturity, rather than delaying it. A nitrogen-deficient plant is generally small and develops slowly because it lacks the nitrogen necessary to manufacture adequate structural and genetic materials. It is usually pale green or yellowish because it lacks adequate chlorophyll. Older leaves often become necrotic and die as the plant moves nitrogen from less important older tissues to more important younger ones.

On the other hand, some plants may grow so rapidly when supplied with excessive nitrogen that they develop protoplasm faster than they can build sufficient supporting material in cell walls. Such plants are often rather weak and may be prone to mechanical injury. Development of weak straw and lodging of small grains are an example of such an effect.

Fertilizer Management:

Nitrogen fertilizer rates are determined by the crop to be grown, yield goal and quantity of nitrogen that might be provided by the soil. Rates needed to achieve different yields with different crops vary by region, and such decisions are usually based on local recommendations and experience.

Factors that Determine the Quantity of Nitrogen Supplied by the Soil:

• The quantity of nitrogen released from the soil organic matter.
• The quantity of nitrogen released by decomposition of residues of the previous crop.
• Any nitrogen supplied by previous applications of organic waste.
• Any nitrogen carried over from previous fertilizer applications.
Such contributions can be determined by taking nitrogen credits (expressed in lb/acre) for these variables. For example, corn following alfalfa usually requires less additional nitrogen than corn following corn, and less nitrogen fertilizer is needed to reach a given yield goal when manure is applied. As with rates, credits are usually based on local conditions.

Soil testing is being suggested more often as an alternative to taking nitrogen credits. Testing soils for nitrogen has been a useful practice in the drier regions of the Great Plains for many years, and in that region, fertilizer rates are often adjusted to account for NO3- found in the soil prior to planting. In recent years, there has been some interest in testing cornfields for NO3- in the more humid regions of the eastern United States and Canada, utilizing samples taken in late spring, after crop emergence, rather than before planting. This strategy, the pre-side-dress nitrogen soil test (PSNT), has received a great deal of publicity and seems to provide some indication of whether additional side-dressed nitrogen is needed or not.

Fertilizer Placement

Placement decisions should maximize availability of nitrogen to crops and minimize potential losses. A plant’s roots usually will not grow across the root zone of another plant, so nitrogen must be placed where all plants have direct access to it. Broadcast applications accomplish this objective. Banding does also when all crop rows are directly next to a band. For corn, banding anhydrous ammonia or urea ammonium nitrate (UAN) in alternate row middles is usually as effective as banding in each middle because all rows have access to the fertilizer.

Moist soil conditions are necessary for nutrient uptake. Placement below the soil surface can increase nitrogen availability under dry conditions because roots are more likely to find nitrogen in moist soil with such placement. Injecting side-dressed UAN may produce higher corn yields than surface application in years when dry weather follows side-dressing. In years when rainfall occurs shortly after application, subsurface placement is not as critical.

Subsurface placement is normally used to control nitrogen losses. Anhydrous ammonia must be placed and sealed below the surface to eliminate direct volatilization losses of the gaseous ammonia. Volatilization from urea and UAN solutions can be controlled by incorporation or injection. Incorporating urea materials (mechanically or by rainfall shortly after application) is especially important in no-till situations in which volatilization is aggravated by large amounts of organic material on the soil surface. Applying small amounts of "starter" nitrogen as UAN in herbicide sprays, however, is usually of little concern.

Placing nitrogen with phosphorus often increases phosphorus uptake, particularly when nitrogen is in the NH4+ form and the crop is growing in an alkaline soil. The reasons for the effect are not completely clear, but may be due to nitrogen increasing root activity and potential for phosphorus uptake, and nitrification of NH4+ providing acidity, which enhances phosphorus solubility.

Timing of Nutrient Application

• Timing has a major effect on the efficiency of nitrogen management systems. Nitrogen should be applied to avoid periods of significant loss and to provide adequate nitrogen when the crop needs it most. Wheat takes up most of its nitrogen in the spring and early summer, and corn absorbs most nitrogen in midsummer, so ample availability at these times is critical. If losses are expected to be minimal, or can be effectively controlled, applications before or immediately after planting are effective for both crops. If significant losses, particularly those due to denitrification or leaching, are anticipated, split applications, in which much of the nitrogen is applied after crop emergence, can be effective in reducing losses. Fall applications for corn can be used on well-drained soils, particularly if the nitrogen is applied as anhydrous ammonia amended with N-Serve®; however, fall applications should be avoided on poorly drained soils, due to an almost unavoidable potential for significant denitrification losses. When most of a crop’s nitrogen supply will be applied after significant crop growth or positioned away from the seed row (anhydrous ammonia or UAN banded in row middles), applying some nitrogen easily accessible to the seedling at planting ensures that the crop will not become nitrogen deficient before gaining access to the main supply of nitrogen.

Minimizing Fertilizer Losses:

• The major mechanisms for nitrogen fertilizer loss are denitrification, leaching and volatilization. Denitrification and leaching occur under very wet soil conditions, while volatilization is most common when soils are only moist and are drying.
• Practices for Avoiding Nitrogen Fertilizer Losses
Gains of Nitrogen to the Soil

Biological and Atmospheric Fixation:

Conversion of atmospheric nitrogen to ammonium which is subsequently available for plant uptake. Direct additions of commercial and organic fertilizers.

Transformations in the Soil

Mineralization:

Conversion of organic nitrogen to ammonium.

Nitrification:

Conversion of ammonium to nitrate

Using an NH4+ source of nitrogen acidifies the soil because the hydrogen ions (H+) released during nitrification of the NH4+ are the major cause of acidity in soils. Over time, acidification and lowering of soil pH can become significant.

Nitrogen fertilizers containing NO3- but no NH4+ make the soil slightly less acidic over time, but are generally used in much lesser quantities than the others. The acidification due to NH4- nitrogen is a significant factor in the acidification of agricultural fields, but can easily be controlled by normal liming practices.

Losses of Nitrogen from the Soil

• Denitrification: Conversion of nitrate to atmospheric forms of nitrogen.
• Volatilization: Loss of gaseous ammonia to the atmosphere.
• Run-off
• Leaching
• Consumption by plants and other organisms
Fertilizing Legumes with Nitrogen

Because the Rhizobia bacteria that infect legume roots normally supply adequate nitrogen to the host plant, well-nodulated legumes rarely respond to additions of nitrogen fertilizer. Occasionally, however, soybeans may respond to applications of nitrogen late in the season, presumably because nitrogen fixation in the nodules has declined significantly. Such responses are quite erratic, though, and late-season applications of nitrogen to soybeans are not routinely recommended. The amount of atmospheric nitrogen fixed by non-symbiotic soil organisms varies with soil types, organic matter present and soil pH.

Nitrogen is a very dynamic element. It not only exists on Earth in many forms, but also undergoes many transformations in and out of the soil. The sum of these transformations is known as the nitrogen cycle.

>ROLE OF VINEGAR

Did you know that you can use ordinary vinegar as an eco-friendly herbicide, fungicide and insecticide?

Uses :

• To kill Pests:

  Spray it where you need it. First of all, for those of you who are plagued by pests and little critters in the garden, fret no more. It will keep cats at bay if you spray in areas you want to deter them, particularly that sand-pit you may have in the garden for the children but those cats will insist on using as their own private toilet! Heavily spray full-strength vinegar around the edges of the sandpit and remember to re-apply after it rains.

• Keep Rabit Away:

  For rabbits, soak corncobs. Are those rabbits eating your vegetables, particularly your beans and peas? Soak corncobs in full strength vinegar for a couple of hours until they are thoroughly soaked. You may even soak them over-night if you wish. Then place the cobs strategically around your veggie patch. They will keep rabbits away for as long as you re-soak your corncobs every two weeks.

• Get rid of Ants:

  Spray the thresholds to get rid of ants. Do you have an ant problem? Again you can apply this full-strength to the ants and they will not come anywhere near the stuff. This is very useful if you find a trail of them making a way into your house. Just spray the thresholds and reapply every couple of days to ensure that they stay away.

• Use as Insecticide:

  Use as an eco-friendly insecticide. Slugs are real pests, because they eat both vegetables, especially lettuces and plants, especially hostas. In this case, vinegar acts as a poison to the slugs because, if you spray slugs with it directly, they will die. You can treat snails in exactly the same way. However, because vinegar is also a herbicide, be careful where you spray your vinegar. Salvia, for example, will die if accidentally sprayed.

• For Fruit Trees:

  Save your fruit trees. Are your fruit trees being invaded by fruit flies? Try this fruit fly bait, which is deadly and effective. Take 1 cup of water, a half a cup of cider vinegar, a quarter of a cup of sugar and 1 tablespoon of molasses. Mix it all together. Take old tin cans without their lids and make two holes in opposite ends for wire handles. Attach the handles and add an inch of the mixture to each can. Hang 2 - 3 tins in each tree. Check on the traps on a regular basis to refill and clean when necessary.

• Protect your tools:

  After you have been digging in the garden with your gardening tools, soak them in a bucket of half-strength vinegar. This will act as a fungicide and kill off anything that may be lurking unsuspectingly so that there is no possibility of cross-contamination when you use them next.

• Use as a fungicide:

  Are your garden plants struggling and your roses suffering from black spot or other fungal diseases? Take 2 tablespoons of white vinegar and mix it with 4 liters (1.1 US gal) of compost tea. Now spray your garden plants with this mixture and see the difference. For roses, the method is slightly different. Take 3 tablespoons of cider vinegar, and mix it with 4 liters (1.1 US gal) of water to control those fungal diseases. Of course, don't forget the compost tea either on your roses to get the best results. For powdery mildew take 2-3 tablespoons of cider vinegar and mix with 4 liters (1.1 US gal) of water and spray your plants. This will help control the problem.

• Increase soil Acidity:

  Increase the soil's acidity. What about your acid-living plants like azaleas, gardenias and rhododendrons? Are they flowering as well as they could be? If not increase the soil's acidity. In hard water areas, add 1 cup of vinegar to 4 liters (1.1 US gal) of tap water. It will also release iron into the soil for the plants to use. And if you have too much lime in your garden, add vinegar to neutralize it.

• Fight Weeds:

  Use to fight inappropriate grass or weeds. Do you have weeds coming up in between your paving slabs on our driveway or pathway that you cannot remove by hand? Don't use a herbicide that is known to damage the environment. Use an eco-friendly alternative instead. Take 1 liter (0.3 US gal) of boiled water, 2 tablespoons of salt and 5 tablespoons of vinegar. Mix it all together, and while it's still hot, pour onto the offending plants.

• Increase/Improve Germination:

  Improve germination. Did you know that you can improve your germination success rate of seeds by using vinegar? This is especially useful for those seeds that are more difficult to germinate such as asparagus and okra, morning glories and moonflowers. Rub the seeds gently first between two pieces of coarse sandpaper. Then soak the seeds overnight in 500 ml of warm water, 125 ml of vinegar and a squirt of washing-up liquid. Plant the next day as normal. You can use the same method, but without the sandpaper for nasturtiums, parsley, beetroot, and parsnips.

Iron (Fe) is classified as a micronutrient, meaning it is required by plants in lesser amounts than primary or secondary macronutrients. Do not let the classification create confusion as iron is very important to the health and growth of plants. Of the micronutrients, iron is needed in the greatest quantity and its availability is dependent on the pH of the growing medium. All micronutrients, except molybdenum, become less available as the growing medium's pH increases, but become more available as the growing medium's pH decreases. The ideal pH range for crops is determined primarily by their ability to acquire micronutrients.
  Function of Iron: Iron is a constituent of several enzymes and some pigments, and assists in nitrate and sulphate reduction and energy production within the plant. Although iron is not used in the synthesis of chlorophyll (the green pigment in leaves), it is essential for its formation. This explains why plants deficient in iron show chlorosis in the new leaves.
  Iron For Plants: Why Do Plants Need Iron? Every living thing needs food for fuel to grow and survive, and plants are just like animals in this regard. Scientists have determined 16 different elements that are crucial to healthy plant life, and iron is a small but important item on that list. Let’s learn more about the function of iron in plants.
What is Iron and its Function? The role of iron in plants is as basic as it can get: without iron a plant can’t produce chlorophyll, can’t get oxygen and won’t be green. So what is iron? The function of iron is to act much like it does in a human bloodstream — helping to carry important elements through a plant’s circulatory system.
Where to Find Iron for Plants: Iron for plants can come from a number of sources. Ferric oxide is a chemical present in soil that gives dirt a distinctive red color, and plants can absorb iron from this chemical. Iron is also present in decomposing plant matter, so adding compost to your soil or even allowing dead leaves to collect on the surface can help to add iron to your plants’ diet.
  Why Do Plants Need Iron? As previously stated, it’s mostly to help the plant move oxygen through its system. Plants only need a tiny amount of iron to be healthy, but that small amount is crucial. First of all, iron is involved when a plant produces chlorophyll, which gives the plant oxygen as well as its healthy green color. This is why plants with an iron deficiency, or chlorosis, show a sickly yellow color to their leaves. Iron is also necessary for some enzyme functions in many plants. Soil that is alkaline or has had too much lime added often causes an iron deficiency in the plants in the area. You can correct it easily by adding an iron fertilizer, or evening out the pH balance in the soil by adding garden sulfur. Use a soil test kit and speak with your local extension service for testing if the problem persists.
IRON AVAILABILITY TO PLANTS: Although most of the iron on the earth crust is in the form of Fe3+, the Fe2+ form is physiologically more significant for plants. This form is relatively soluble, but is readily oxidized to Fe3+, which then precipitates. Fe3+ is insoluble in neutral and high pH, making iron unavailable to plants in alkaline and in calcareous soils. Furthermore, in these types of soil, iron readily combines with phosphates, carbonates, calcium, magnesium and hydroxide ions. In such types of soils, it is recommended to use iron chelates. 
IRON UPTAKE BY PLANTS: Plants uptake iron in its oxidized forms, Fe2+ (ferrous form) or Fe3+ (ferric form). Plants use various iron uptake mechanisms. One of these is the chelation mechanism => the plant releases compounds called siderophores which bind iron and enhance its solubility. This mechanism also involves bacteria. Another mechanism involves the release of protons (H+) and reductants by the plant roots, to lower pH levels in root zone. The result is increased iron solubility. In this respect, choice of the form of nitrogen fertilizer is significant. Ammonium nitrogen increases proton release by roots, thus lowering pH and facilitating iron uptake. Nitrate nitrogen enhances the release of hydroxide ions that increase pH in the root zone and counteract efficient iron uptake. New roots and root hairs are more active in iron uptake, therefore it is imperative to maintain a healthy active root system. Any factor interfering with root development interferes with iron uptake.
Iron Sources: A few water sources provide sufficient iron for most crops, but this is unusual. Iron is typically provided by a fertilizer and most plants prefer a constant iron application rate of 1 ppm. Plants such as calibrachoa, diaschia, petunia, scaevola, snapdragon, etc.
MANAGING IRON DEFICIENCIES:
Iron Deficiency: Iron deficiency is expressed as an interveinal chlorosis of the new leaves (leaves are yellow with green veins). To determine the cause of the deficiency, first examine the roots. Plant roots that are diseased or stressed from overwatering do not take up nutrients efficiently, causing chlorosis. It is important to allow the growing medium to dry out between waterings to reduce plant stress, and to apply an appropriate fungicide drench if roots are diseased. Iron deficiency in Calibrachoa.Iron deficiency in Petunia.Iron deficiency in zonal Geranium If the roots are healthy, send a sample of the growing medium and plant tissue from several plants to a lab for verification. The pH of the growing medium directly affects the uptake of iron by plants. If the pH of the growing medium exceeds 6.5, iron is converted to a form that is unavailable to the plant, causing deficiency. The pH of the growing medium can be reduced by acidifying the irrigation water and/or using a fertilizer with a higher potential acidity. Since this may take up to a few weeks to correct the problem, chelated iron can be used to quickly green up the plants. The most effective chelating agent is iron-EDDHA. However, iron-DTPA is almost as good. If testing shows iron is deficient in the growing medium and tissue, but that the growing medium pH is normal, look at the fertilizer application rate. Fertilizing at low nitrogen rates means that iron is also being applied at low rates. Increasing the fertilizer application rate may take care of the problem. However, calibrachoa, diaschia, petunia, scaevola, snapdragon, etc. require additional iron over and above what most fertilizers supply. Therefore, iron chelates may need to be added to your fertilizer program. Iron deficiency is a limiting factor of plant growth. Iron is present at high quantities in soils, but its availability to plants is usually very low, and therefore iron deficiency is a common problem. When iron deficiency is identified, it can be treated in the short term by applying a foliar spray of iron, but the best course of action is prevention. Therefore, the grower should identify the real cause of the deficiency and treat it, in order to prevent the problem from occurring in the future.
Often, iron deficiency does not indicate insufficient iron supply. It may also be related to various conditions that may affect iron availability. For example: carbonate levels in the soil, salinity, soil moisture, low temperature, concentration of other elements (e.g. competitive microelements, phosphorus, calcium) etc. Evaluating these factors and correcting them can save a great deal of money spent on ineffective and unnecessary iron applications. The reason for testing is to check the levels of other micronutrients in the growing medium and tissue. Often, the deficiency symptoms of manganese and other micronutrients look like an iron deficiency. Correcting an iron deficiency will not help if another micronutrient is deficient.
Iron Toxicity: Iron toxicity occurs due to a low growing medium pH or from an excessive application of iron. Iron-manganese toxicity, as it is commonly referred to, is more common in zonal geraniums, African marigolds, lisianthus, New Guinea impatiens, pentas, or other crops that prefer the growing medium's pH to be 5.8-6.6. Again, have the growing medium and tissue tested to confirm the problem. If the pH of the growing medium is a problem, but less than 0.5 pH unit below the normal range for the plant, alternate fertilizer applications with a potentially basic fertilizer (15-0-15, 14-0-14, 13-2-13, etc.) and, if applicable, refrain from injecting acid.
  Iron-Manganese toxicity in Geranium. Chloloris affecting leaves. If the pH of the growing medium is more than 0.5 unit below the normal range, drench with potassium bicarbonate or liquid limestone. With either product, rinse the foliage with clear water to remove residues and avoid phytotoxicity. Potassium bicarbonate (2 lb/100 gallons of water) adjusts a growing medium's pH quickly, but provides 933 ppm potassium and increases soluble salt levels in the growing medium. Liquid limestone does not increase EC and has a longer staying power, but takes one week to fully adjust pH. Keep in mind that it is abrasive to injectors and requires agitation in stock solutions.