Plant Nutrients -- They eat just like us.

(A/N: This page will be linked to the Fertilisers page when it is operational,)

Basics : Deficiancy : Toxicity Identification : Groups

Macronutrients - N : P : K

Secondary Macronutrients - Ca : Mg : S

Micronutrients - B : Cl : Cu : Fe : Mn : Mo : Ni : Zn

 

Plant nutrients are often mysticized and the complex interactions that occur between them are often confusing and poorly understood by even professional gardeners. Most soil, where plants naturally can establish must have the correct nutrients for a plant to complete its lifecycle.

This is sufficient for almost everywhere on earth, this is because when a plant grows it uses nutrients and when it dies, then decays its material is broken down again and returnes nutrients to the soil where it acts as a source of food for other plants and animals. some matter is lost and some is gained, pulled up from the subsoil by deep rooted plants, all in all a rough balance is formed.

If this is idyllic in the wild, in cultivated areas this is more problematic, humans grow plants for a reason. With some plants we take the fruit and therefore all of the nutrients that have been paid into its production, even ornamental plants suffer this fate, blooms are taken and when they are finished the plants are removed and discarded.

Filling Up

Over time as nutrients are removed, they need to be replaced. The quickest and easiest way to do this is to use fertilisers, this can be through a number of ways such as powders or liquids, they can be chemical or "organic" and they can be fast or slow. There is a vast range and all of them have a particular use. There are other ways however, such as manure and compost. Using these is slower , time consuming and less effective but helps build the soil structure. Another way is to leave the soil fallow, or even better using  green manure plants which you can grow to actually add nutrients to the soil! All these methods can be used, however they all have their flaws as well as their benefits.

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Deficiency

When a plant can't find the nutrients it requires for proper growth and operation then it becomes deficient, this is severe and can, if a key nutrient stunt or kill the plant, however if the deficiency is noted then it can be treated quickly and plants often recover well. If a plant has become deficient then a liquid fertiliser is ideal as they work quicker, although they do not have the persistence of most solid feeds. Some nutrients are mobile and can be moved around the plant to areas that are more important to the plant, whilst others such as silicon or calcium cannot, it would be the equivalent of moving our finger bones to our ribs to heal a crack. Knowing which nutrients are mobile is key to identifying certain deficiencies.

Deficiency can be caused by a number of things, ranging from cool root regions, low salt content or too high water content to other nutrients causing mineral antagonism and blocking other elements from being used!

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Toxicity

Interestingly it is possible to overfeed plants, causing toxicity. This can cause a wide range of problems, some quite insidious. The main problem is simply growth bias, not truly toxicity it is when nutrients alter the growth pattern of the plant. The perfect example is a tomato, if overfed with a nitrogen based feed, it produces a great number of leaves, is overfed with a potassium feed, it produces too many fruit to sustain. In cases like this, nutrients work against each other. More sinister is when nutrients start to impact others, for example a high potassium feed will directly reduce the uptake of magnesium among others, causing inter veinal chlorosis particularly in ericacious plants!

In many cases where physical toxicity occurs, it is because nutrients have been taken up to the plant as salts and over accumulated over time, therefore the majority of annual plants are free from this buildup whilst it is more likely to occur on longer lived woody plants.

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Identification

Identification is a major part of treatment for disorders but unfortunately it is easy to miss-diagnose, When you look at a plant then first take note of what is happening, how it is expressed and where it is. This is particularly important with deficiencies that can otherwise be confused. For example yellowing leaves:

A tomato has yellow leaves, the yellowing started at the bottom of the plant and its veins are green.

Yellowing leaves are caused by six deficiencies: Nitrogen, Iron, Magnesium, Manganese, Sulphur and Potassium

Nitrogen causes the whole leaf to yellow, and is mobile so it normally starts at the bottom

Iron causes the leaf to yellow interveinally and is not mobile so it normally starts at the top

Magnesium causes inter veinal yellowing and is mobile so it starts at the bottom

Manganese causes inter veinal yellowing and causes stunting.Its symptoms are normally universal.

Potassium causes marginal chlorosis, poor fruiting, stunting and disease susceptibility universally

Sulphur causes the whole leaf to yellow and is constantly consumed so the plant yellows universally

Click for answer will be implemented later

This example illustrates knowing there are similarities between deficiency and you need to know which they are to treat it. If nitrogen was applied, it would have made the plant weaker as it would encourage growth the plant could not support and Iron would have only masked the problem temporarily whilst doing nearly nothing to help.

In this case it is most likely Magnesium deficiency given the symptoms, especially given tomatoes are normally over-fed with potassium.

When looking up nutrient problems then remember not only do symptoms vary between plants but they can be caused or masked by other issues such as water stress or pest attack.

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Nutrient groups

There are four groups of nutrients, the first contains Carbon, Oxygen, and Hydrogen. Carbon is a main structural element of plants but is also used chemically, whilst Oxygen and Hydrogen along with water are predominantly used in photosynthesis and respiration. As even the worst gardener is unlikely to be growing their plants in a vacuum, they are largely irrelevant here (carbon is a bit more involved but we will come to that later). The first three elements are responsible for 90-96% of the dry weight of a plant!

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Macro-elements

These are the elements most commonly found in fertilisers, they make up between 0.02% and 4% of the dry weight of a typical plant, a far cry compared to the three prime elements but this is a far larger amount than it sounds!

N : P : K

Nitrogen

This is one of the main building blocks of a plant. used in DNA, Cell walls and proteins it is truly indispensable and it is the only part of a protein the plant cannot produce itself through photosynthesis. The importance of nitrogen cannot be overstated.

Nitrogen
Deficiency Nitrogen deficiency causes the entire leaf to pale to yellow progressing to white, It starts on older leaves at the bottom as it is moved up to the younger leaves. As it progresses, smaller leaves are produced and the stem weakens. Eventually necrosis starts on the leaves. Occasionally the veins are pale first.
Toxicity Leaves are produced to the expense of everything else, the abundant foliage is dark green and thick. The plant however will not produce the proper root system or fruit. This will lead to the leaves drying up and eventually fall off.
Key words Lower Leaves, Whole leaf yellowing, eventually weak stems.

To Treat: Sulphate of ammonia, Growmore, most other feeds

Phosphorus

In plants Phosphorus holds a very similar role to in humans, it is the energy carrier, allowing all chemical reactions to take place by storing energy in chemical bonds to be released where needed. It also encourages root  growth and general health of the plant. A plant deficient will by contrast be small and very weak as it cannot properly power itself.

Phosphorus
Deficiency
Phosphorus deficiency will result in a slow growing stunted plant with dark leaves that start to slowly turn purple as chlorophyll production is impaired and anthrocyanin is produced. Plant maturity is greatly delayed as is any fruiting or flowering of plants. Advanced stages of deficiency result in necrotic patches on older leaves as it begins to fail.
Both pictures are deficiency
P Deficiency
Toxicity Phosphorus can interfere with copper and zinc uptake although this is incredibly rare due to pH differences. Can cause curling of leaves and chlorosis with necrosis of the apical tip. This should be considered the least likely option.
Key words Purple, Lower Leaves, Stunted, Slow Growth.

To Treat: Superphosphate of Lime, Growmore, Vitax Q4

Potassium

Potassium is best known for tomato feed, it is used in high concentrations in both tomato and bedding feeds and is considered by most to purely be a fruit booster. That is doing it a huge disservice.

The hidden roles of potassium are perhaps more impressive, it helps a plant resist drought and keep cells turgid by moderating water and salt iconically, it helps strengthen the vascular system resulting in more disease resistance against wilts, rust and root rots whilst also being vital for moving starches and sugars around which is where the byproduct of better quality fruit comes from, all whilst aiding photosynthesis in the background.

Potassium
Deficiency
Potassium deficiency will cause chlorosis on edge of leaves that later look scorched and necrotic whilst moving further in, poor fruiting or misshapen fruit, disease susceptibility and fragile stalks. As potassium is held poorly by the soil it is best to feed it with organic fertiliser or by small amounts often.
Toxicity Toxicity is unusual but when it occurs it reduces uptake of magnesium, zinc iron and manganese, causing inter veinal chlorosis. Any compound feed will exacerbate this rather than help. First flush the plant with water well and then apply sequestered iron.
Key words Chlorosis on edge, Necrotic Edge, Lower leaves first, Fragile Stems, Scorched.

To Treat: Tomato Food, Potash, Vitax Q4, Rose Fertilizer

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Secondary macronutrients

Secondary nutrients are just as vital for plant growth as the primary macronutrients and although they are found in lower quantities, they are still much more prolific in a plant than the micronutrients. The reason they are given lower priority is the soil almost always has a sufficient supply of these elements and they are only occationally the limiting factor. In many cases the nutrients are added to the soil through weathering, or other natural processes.

Ca : Mg : S

Calcium

Calcium is extremely important to plants, it works through many different processes but specifically it is used to keep growth points healthy (as it is immobile this requires a constant supply), it strengthens and elongates cell walls. increasing the strength and durability of the plant (again mostly at the growth points) regulates protein synthesis and by doing so helps reduce deterioration by ageing, effectively lengthening the plant's lifetime.

A deficient plant will have problems with its growth as growing points fail, this has a severe impact on fruit and grass tends to fail.

Calcium
Deficiency

Calcium deficiency inhibits bud formation and causes numerous problems with fruit, including poor storage as water transport starts to fail. A lack of calcium causes disorders such as blossom end rot to increase in severity. The plant will produce stunted yellow leaves and have a poor root system. Vascular breakdown may in extreme cases cause shrinkage of the stem and wilting leaves.

As Calcium is used constantly but is not mobile it is required at a steady rate

1
Toxicity No toxicity is noted however it is antagonistic to magnesium and can cause deficiencies in large amounts.
Key words Fruit disorder, Blossom end rot, Stunted Leaves, Wilting.

To Treat: Superphosphate of Lime, Garden Lime, Vitax Q4

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Magnesium

Magnesium is actually the only mineral element used in chlorophyll, despite the common belief Iron is used. It therefore is absolutely indespensible to plants (barring rarities such as birds nest orchids). It is a particularly common deficiency with tomatoes as their feed is designed to boost fruit by adding potassium, which inhibits take up of Magnesium. As it is not held well in the soil, sandy conditions often lead to Mg deficiency (although thankfully this is uncommon in Bristol.

 

Magnesium
Deficiency

Magnesium deficiency initially expresses itself as a chlorosis of the lower old leaves, this can be yellow or red depending on the plant. Leaves become brittle and fall off easily, whilst fruit yield is severely reduced and can fall prematurely.

Deficiency is common where there has been a high amount of manure, green manure or potassium feed and is exacerbated by rain and cold conditions.

Toxicity Magnesium Toxicity is not visibly apparent and if there are problems caused by it, they are not notable.
Key words Lower Leaves, Interveinal, Chlorosis.

To Treat: Sequestrine, If not fed potash previously Vitax Q4

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Sulphur

Sulphur (and yes that is its correct spelling) is surprisingly common in plants, it is an important plant constituent and helps the plant use nitrogen (hence the similarities in deficiency) Deficiency is particularly damaging in young legumes as they need it for their roots to develop the nitrogen fixing bacteria they are known for. Interestingly deficiency is less common in urban environments due to pollution replenishing sulphur in the soil. Without Sulphur, proteins and therefore chlorophyll and enzymes are not produced. It is responsible for many of the taste and scent compounds in plants such as garlic.

Sulphur
Deficiency
Very similar to mild nitrogen deficiency, yellowing of the entire leaf and quickly spreading globally around the plant. Leaves tend to curl downwards. Legumes are affected worse as they struggle to produce root nodules further depriving them of nitrogen. Taste and smell of plants is reduced and grass crops such as wheat or ornamental grasses are weakened. Sometimes causes purpling on leaf edges
Toxicity When overabundant in the soil, leaf size is reduced and the leaves may appear scorched. When applied directly to leaves it will cause burning and scorching as it is highly toxic in large amounts
Key words Light whole chlorosis, leaves may curl, possible purple edges.

To Treat: Sulpher dust, Vitax Q4

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Microelements

The distinction between Macroelements and Microelements is somewhat arbitrary and a common misconception is that the following elements are less important to the plant, this is completely wrong and the only difference is the amount used by the plant is lower in the following. A deficiency will still cause serious problems and a lot of these are not used in conventional fertilisers.

B : Cl : Cu : Fe : Mn : Mo : Ni : Zn

Boron

Boron is used primarily in cell division along the meristem and therefore is strongly linked to pollen viability and flower/fruit formation. It is rarely a deficiency but is found most often in long term potted fruit trees as amounts are continually lost with no way to replenish supply. May render plants deficient temporarily infertile.

Boron
Deficiency
Boron deficiency often expresses as cracking throughout the plant as the meristem dies, occasionally forming gummy deposits (gummosis) that look almost like amber. Plant material can become brittle and easily damaged. Most deficiencies are noted on edible crops such as apples and beetroot where the core of the plant is affected. Can cause purple spots on some leaves http://image.absoluteastronomy.com/images/topicimages/b/bo/boron_deficiency_(plant_disorder).gif
Toxicity Generally found in top fruit, lemons and blackberries are particularly susceptible, with apples and other top fruit not far behind. Initially there is yellowing and necrosis of the tips and outside edges of leaves however some plants do not accumulate in leaves and instead it causes a number of problems with the fruit.
Key words Fruit, Cracking, Gumming, Purple Spots, Malformed fruit cores.

To Treat: Vitax Q4, Seaweed feed

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Chlorine

Chlorine (used as Chloride) is an interesting element, it is normally suppled by rain and is present in most tapwater, traditionally it has always been an element that causes problems via toxicity rather than deficiency. Because it is abundant in most soils, the main risk to this element being removed is that it is highly leachable in water and therefore if only tap water is used (where some people allow it to evaporate chlorine) or distilled water then potentially a chlorine deficiency may develop.

Chlorine
Deficiency
When there is a chlorine deficiency then leaves tend to wilt, becoming chloritic and then bronzed whilst the roots fail to develop properly, becoming thick and inefficient. 1
Toxicity Chlorine toxicity is characterised by the typical scorching of leaf marginal and a bronzing similar to the symptoms of deficiency. A reduced growth rate and reduced leaf size is also common.
Key words Bronze, Chlorosis, Wilting, Roots

To Treat: Vitax Q4, Seaweed feed

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Copper

Copper is another microelement often linked with production of chlorophyll, it is used for enzyme activity and vital for seed production. Despite this wide portfolio it is only used in very small amounts and deficiencies are occasional and hard to spot.

Copper
Deficiency
Copper deficiency is hugely varied and can cause results from mild chlorosis on older leaves to young leaves that become very dark and curl, whilst developing a wilted appearance. In severe conditions then leaves will form necrotic spots and start to die back. http://keys.lucidcentral.org/keys/sweetpotato/key/Sweetpotato%20Diagnotes/Media/Html/TheProblems/MineralDeficiencies/CopperDeficiency/Cu%20deficiency5.jpg
Toxicity Copper is hugely toxic in large amounts (which has almost caused Bordeaux mixture to be withdrawn numerous times) and results in symptoms similar to Iron deficiency whilst also causing curling leaves and thickened roots.
Key words yellow leaves, dark leaves, twisted leaves.

To Treat: Vitax Q4, Seaweed feed

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Iron

Iron is the best known micronutrient deficiency, with its importance often on par with nitrogen, in reality it is not as damaging as some however it is highly widespread due to the propensity of deficiency by pH. If this is suspected then check if the plant is in the right pH soil otherwise correcting it can be both time-consuming, expensive and utterly pointless.

It is used in production of chlorophyll, photosynthesis and oxidisation whilst being important in the plants use of nitrogen.

As iron is non-mobile it is almost always apparent first on young leaves.

Iron
Deficiency
Iron Deficiency is commonplace and should be one of the first considered when there is inter veinal chlorosis of the leaves. Chlorosis is quick to appear and is very pronounced, if not treated the plant will rapidly loose vigour and yield will reduce along with quality.
Toxicity Iron toxicity is rare and when it appears it is seen most often as small copper spots on the foliage of plants.
Key words Yellow leaves, green veins, young leaves.

To Treat: Vitax Q4, Seaweed feed

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Manganese

Manganese is another general purpose micronutrient that has a number of important effects on the plant, such as chlorophyll production (don't they all?) and metabolism but is used only in trace amounts.

Manganese
Deficiency

Deficiency is shown by a whole-plant inter veinal chlorosis, often with pinpricks of worse affected areas. Later as the deficiency worsens becomes grey and follows the veins, then spreading and the leaf withers.

It is most common on alkaline sandy soils where there is low organic matter to retain it. Good garden care should make this extremely unlikely.

Toxicity In the rare occasions there is a toxic level of Manganese the leaf will suffer poor vigour and growth will slow, with mild chlorosis forming.
Key words Yellowing Leaves, Grey veins

To Treat: Vitax Q4, Seaweed feed

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Molybdenum

If you can pronounce this without studying chemistry you have missed your calling! This element is one of the lowest used in plants. It is used in processing nitrogen.

Molybdenum
Deficiency
Molybdenum deficiency is generally detected first as a weak nitrogen deficiency that is sometimes inter veinal as it is used in the conversion from nitrates to a more useable form. There are other symptoms dependent on the plant and these are varied but there is often a red sheen underneath the leaves and an upwards curl. 1
Toxicity Molybdenum has one of the most unique symptoms for toxicity in many plants, at high levels it turns leaves vivid orange!
Key words Yellow leaves, curling leaves.

To Treat: Vitax Q4, Seaweed feed

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Nickle

Very little is known about the use of nickle in plants, it is linked to enzyme use, leguminous plants and metabolism but otherwise very little is known.

Nickle
Deficiency
Nickle deficiency causes 'mouse ear' necrosis in plants where it damages the tips of leaves severely. In rhizomatous plants such as beans and peas, it reduces growth.
Toxicity None known
Key words leaf tip necrosis and yellowing

To Treat: Vitax Q4, Seaweed feed

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Zinc

This element is again found only in small amounts in plants, it is not clearly known for what use its required however the deficiency symptoms hint that it is used in metabolism and distortions on the edge of leaves indicate some interaction with the meristem.

Zinc
Deficiency
Zinc deficiency introduces inter veinal chlorosis with dark green veins, much like a recovering iron deficiency, it also causes disturbance along the leaf margins forming wrinkled patterns. plants with severe deficiencies have a very small internode meaning leaves are produced close together to form a rosette pattern. Can cause dieback on foliage.
Toxicity Zinc is incredibly toxic in large amounts and causes rapid plant death with yellowing symptoms as it interferes with iron.
Key words Yellowing Leaves, Wrinkles.

To Treat: Vitax Q4, Seaweed feed

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