Old Reviews primary macronutrients

[woody]

found this article online,wasn't sure where to post this, mods feel free to move this or delete if its a repost


Primary Macronutrients

Element
Nitrogen (N)

Uses within the plant
- Helps plants form and use proteins, carbohydrates, hormones, chlorophyll, vitamins, enzymes and amino acids
- Dictates how plants function inside
- Pushes vegetative growth through the production of new leaves and helps establish the shape and size of the plant through stem development

The presence of nitrogen is vital for enabling the plant to carry out most of its functions.

Mobility
Mobile - easily moved around the plant - deficiency first visible on older leaves because what nitrogen is available can be directed towards supporting new growth.

Signs of Deficiency
A nitrogen deficiency tends to be caused by underfeeding your plants – i.e. you use a very weak nutrient solution for a prolonged period of time and it doesn’t provide the necessary levels of the element.

Signs of a nitrogen deficiency include the following:
- Short, restricted plants as a result of reduced growth
- Pale green/yellow leaves (especially on the older foliage but quickly capable of spreading to newer, top leaves if left untreated) that can lead to the undersides of leaves purpling/browning and possibly even dying and dropping off
- Thin, spindly, purple/brown stems

What to do if you have a deficiency
Slowly increase the strength of your nutrient solutions and also consider using an additive like Vita Link Foliar Feed. By following this advice, you can expect a nitrogen deficient plant to start getting better after about a week. However, affected leaves will not recover from the damage inflicted upon them.

Signs of Excess
Excess nitrogen results from overfeeding your plants – i.e. you use a very strong nutrient solution for a prolonged period of time and it provides too much of the element.

Signs of excess nitrogen include the following:
- Weak, stunted plants
- Leaves that are thick, brittle and dark green
- Disease and bugs due to lack of strength
- Spindly, frail stems
- Vegetative growth instead of flowering
- A deficiency of potassium (k)
- Leaf burn, causing them to turn yellow or brown

What to do if you have excess nutrient
In the event of excess nitrogen, first reduce the amount of the element being supplied to plants (stop the use of foliar feeds, weaken feeds and/or alter the NPK ratio in 3 part nutrients). For problems that persist flush out your plants, media and growing system, only using water in feeds over the course of several days. Next introduce a weaker nutrient solution than before, gradually building it up over time as the plants show signs of recovery. If you’re actively trying to promote a flowering response, make sure a bloom feed is applied.
Notes
Towards the end of the flowering stage you may notice that leaves start turning yellow – this is quite normal and only happens because your plants need to use nitrogen reserves for fueling the growth and development of fruit and flowers.

Too much nitrogen can affect the amount of sugar and vitamins in fruits and vegetables, making them taste different to normal.

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Element
Phosphorous (P)

Uses within the plant
- Helps plants form and use essential oils, sugars and starches
- Changes solar energy into chemical energy (photosynthesis)
- Aids respiration, energy transfer, storage and use of water
- Boosts root growth and produces increased numbers of fruits that are also of a bigger size
- Improves the quality of seeds
- Strengthens plant defenses

The presence of phosphorous is vital for flower and fruit formation.

Mobility
Mobile - easily moved around the plant - deficiency first visible on older leaves because what phosphorous is available can be directed towards supporting new growth.

Signs of Deficiency
A phosphorous deficiency either results from underfeeding your plants (i.e. you use a very weak nutrient solution for a prolonged period of time and it doesn’t provide the necessary levels of the element), from excess amounts of Iron (Fe) or Zinc (Zn) in your nutrient solution, and/or from very acidic conditions reducing the availability of the element.

Signs of a phosphorous deficiency include the following:
- Slowed/stunted growth leading to small leaves
- Small and thin stems that can go purple
- Dark blue-green foliage (tends to occur in older leaves first) that may turn purple, starting on the veins of the undersides of leaves, and then yellow when on the brink of dying (the tips of the leaves die before the change of colour)
- Purple/black spots on leaves, later spreading to stems
- Delayed plant maturity (no/slow flowering) and limited fruit and
seed production

What to do if you have a deficiency
You can’t just add more phosphorous since the problem might be caused by excess of another element. Instead flush out your plants, media and growing system with pH adjusted solution or water, only using this for feeds over the course of several days. Reintroduce a suitable feed afterwards, ensuring that it has a good supply of phosphorous according to the NPK ratio. Beware that excess iron (Fe) and zinc (Zn) in your nutrient solution may cause a phosphorus deficiency – take care if you also want to add in a flowering booster.

For hydroponics we also recommend experimenting with something like Vita Link Buddy, an excellent phosphorus-rich flowering booster. It contains phosphites – as opposed to the phosphates found in most bloom stimulants – which are more readily available to plants, so they can be quickly accessed, internally distributed and then used by the parts that need them.

Coco and soil growers will not want to go without a guano additive either since the rich supply of phosphorous and slow release properties makes them fantastic at promoting root development and strong plant structures during transplanting, and many large, sweet-tasting flowers during the bloom stage. Plagron Bat Guano is a great example of this type of product with a composition of 6% Nitrogen (N), 15% Phosphorus (P) and 4% Potassium (K).

Signs of Excess
Phosphorus is difficult for plants to obtain, let alone get too much of it. In the rare scenario when high levels of phosphorous are present, you may see a plant becoming deficient in Iron (Fe), Magnesium (Mg), Copper (Cu) and Zinc (Zn). Consequently, to tell whether your plant contains more than the necessary amount of phosphorous you’ll often be looking for signs of deficiencies in these elements – including:

- Pale green/yellow colour between the veins of higher, new leaves (deficiency of iron, copper or zinc) or lower, older leaves (deficiency of magnesium).
- Leaf blades die and curl upwards (deficiency of magnesium, copper or zinc)
- Leaves turn white (deficiency of magnesium or iron)
- Purple stems (deficiency of magnesium)
- Small leaves (deficiency of zinc)


What to do if you have excess nutrient
As we will recommend in any case where there’s excess nutrient, immediately flush everything with pH adjusted solution or water for 3 to 4 days. If you don’t notice a difference in your plants, extend this period of time until signs become apparent of visible improvement. Then reintroduce your feed, starting off with a weak mix and gradually working your way up, closely monitoring pH as you go.

Notes
Plants will react to freezing cold conditions in a similar manner to having little phosphorous content so make sure you make a good assessment of the likely cause before taking action.

Phosphorus deficiency is most common when ph is above 7 or below 5.5
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Element
Potassium (K)

Uses within the plant
- Activates enzymes and produces proteins and sugars for building cells and tissue
- Plays a key role in the process of photosynthesis and plant metabolism
- Strengthens stems and the overall plant structure for increased resistance to adverse environmental factors
- Aids the control of water and chemicals within plants
- Improves the flavour and colour of fruit

The presence of potassium is vital for flower and fruit formation.

Mobility
Mobile - easily moved around the plant - deficiency first visible on older leaves because what potassium is available can be directed towards supporting new growth.

Signs of Deficiency
A potassium deficiency either results from underfeeding your plants (i.e. you use a very weak nutrient solution for a prolonged period of time and it doesn’t provide the necessary levels of the element) or from excess amounts of Nitrogen (N) and Sodium (Na) in your nutrient solution.

Signs of a potassium deficiency include the following:
- Slowed/stunted growth of overall plant
- Poorly formed roots and weak stems and stalks
- Older leaves turn pale green/yellow, and some dark spots and burned edges may appear
- Leaves curl and bend in the worst cases
- Disease and bugs due to lack of strength

What to do if you have a deficiency
There’s no quick fix option of simply adding more potassium because the issue could very easily relate to greater than desired quantities of some other element. First of all flush your whole system with a pH-adjusted solution or water, doing so over the course of 3 or 4 days. Then start using an appropriate feed, making sure the one selected has enough potassium compared to the balance of nitrogen and phosphorous. Keep a close eye on the pH and bear in mind that excess Sodium (Na) is able to cause a Potassium deficiency, so carefully monitor the boosters that you also choose to administer.

As soon as your plants return to health, applying a PK booster like PK 13/14 or ATAMI Bloombastic during the flowering phase will aid in the development of fruits and flowers and ensure that your plants are able to support this additional growth.


Signs of Excess
Excess potassium results from overfeeding your plants – i.e. you use a very strong nutrient solution for a prolonged period of time and it provides too much of the element.

Too much potassium in a plant can cause deficiencies of Calcium (Ca), Magnesium (Mg) and Nitrogen (N). As a result, you are able to detect if there is excess potassium in your plant by watching for indicators of deficiencies in these elements – including:
- Short, restricted plants as a result of reduced growth (deficiency of calcium or nitrogen)
- Pale green/yellow leaves that can turn purple/brown (deficiency of nitrogen)
- Thin, spindly, purple/brown stems (deficiency of nitrogen)
- Decaying roots, flowers and insides of plants (deficiency of calcium)
- Yellow/bright green discolouring of the edges of leaves (deficiency of magnesium)
- Crispy/Crinkled leaves (deficiency of calcium or magnesium)
- Brown spots on leaves (deficiency of calcium)

What to do if you have excess nutrient
You’ve guessed it! Flush your system for 3 or 4 days (or until the plants appear as though they’ve begun recovering) with a pH-adjusted solution or water and then apply a feed containing a suitable NPK value. Start out with a low strength, all the time closely watching pH levels.

Since excess potassium often leads to deficiencies in calcium and magnesium, adding a stimulant like Bloom CALMAG, which delivers highly accessible forms of these two elements, will really compliment your existing nutrient package. If you have had a deficiency of calcium and magnesium caused by an excess of potassium it won’t just magically solve the problem – in fact, the product may prove detrimental for those who hope to use it in this way. You first need to give your plants a chance to recover somewhat, which is the purpose of doing a flush.


So as you can see, when plants receive too much or too little of these key nutrients they will soon begin to show you certain signs that all is not right. By being able to recognize the cause of different types of distress and then regularly checking your plants, you put yourself in a prime position to quickly deal with any developing issues, stopping further suffering from occurring and maintaining plant health

 

[woody]

food for thought article

Bit more I found on plant nutrients

Why should you want to know about different nutritional elements?
Towards the start of the last century a lot of research went into identifying both the primary “macro” nutrients (large amounts used by plants), secondary “macro” nutrients (slightly smaller amounts used by plants) and “micro” nutrients/trace elements (small amounts used by plants) that combine to offer complete nourishment following absorption through the roots and leaves. No single element is more important than the next one; plants just require different quantities and concentrations at different stages of their lifecycle. Ever since these successful initial studies took place and all the key nutrients were found, the focus has switched towards investigating the interrelationship of elements (for example you will sometimes find that when there is a large quantity of one element another element becomes deficient) and the most effective combinations.

It’s true that all plants experience a shift in their nutritional requirements as they move from the vegetative stage to the flowering stage. Refer to the important NPK (Nitrogen (N), Phosphorous (P) and Potassium (K)) balance of primary macronutrients and you’ll see how the vegetative cycle dictates a high demand for nitrogen to help build healthy leaves and stem whilst during the bloom cycle upping the ratio of phosphorous and potassium boosts fruit and flower production.
That said, despite these commonalities there are different preferences between plants,
between species and even between clones!

More so than anybody else, growers adopting hydroponic techniques should pay special attention to the food that they feed their plants – since a unique opportunity exists to fine-tune the mix right down to the very smallest detail. Hydroponic nutrient packages are a veritable soup of goodies covering the whole spectrum of required elements, produced in a liquid concentrate form, whereby you just add them to water, check cF and adjust pH to make them available for plants. These can be purchased as one-part, two-part or three-part pre-mixed products, with the simpler of the offerings giving you one option for vegetative growth and one for flowering, and the more advanced packages actually letting you change the ratio of mineral elements at any stage of a crop.

The amount of each element present in a nutrient varies from brand to brand, and also varies based on how many parts make up the product. You can also increase the level of a particular set of elements by introducing liquid and powdered stimulants and boosters with the intention of improving anything from nutrient uptake, root strength, growth rates, flower sizes and fruit flavour. However it is wise to keep things as simple as possible if you are only just starting out. You do not want to bombard your plants with high quantities of all the different types of elements!

So what nutrients does a plant need?
To grow and develop to as near to full potential as possible, each and every plant requires a supply of the following elements:

Primary Macronutrients (large amounts used by plants)
- Nitrogen (N)
- Phosphorous (P)
- Potassium (K)

Secondary Macronutrients (slightly smaller amounts used by plants)
- Magnesium (Mg)
- Sulphur (S)
- Calcium (Ca)
- Silicon (Si)

Micronutrients/Trace Elements (small amounts used by plants)
- Sodium (Na)
- Iron (Fe)
- Manganese (Mn)
- Copper (Cu)
- Zinc (Zn)
- Molybdenum (Mo)
- Boron (B)
- Chlorine (Cl)
- Nickel (Ni)
- Cobalt (Co)

In addition to these elements, a further group of macronutrients exists that are derived from the air and water and include Carbon (C), Hydrogen (H) and Oxygen (O). But since the purpose of this article has been to provide a brief overview of plant nutrition and what you choose to include in the feed regime, the macronutrients derived from the air and water will get covered in a separate article further down the line.

Other growth-influencing factors like light, pH, temperature and humidity merely affect how well a plant uses the elements available to it.

If symptoms of nutrient deficiency/excess appear on new leaves, the problems are usually related to secondary macronutrients and micronutrients whereas if symptoms appear on old leaves, the problems are usually related to primary macronutrients.

How do plants use the available nutrients?
The roots absorb mineral salts from your nutrient solution (or the pre-fertilized media) and the leaves access the beneficial elements from the air and any utilised foliar applications. From here the plant then transports them to areas where they are most needed – for example it will always try and supply more nutrients to the fresh shoots of new growth as opposed to older, established leaves. At this point the issue of nutrient mobility comes into play, given that some elements are more mobile and easily moved around the plant (e.g. nitrogen, phosphorous and potassium) than others. Consequently the lack of a mobile nutrient in the plant is first visible on older leaves, but for a missing, less mobile nutrient the younger leaves suffer because it can’t be moved up to them from the lower, older foliage. With that fact in mind you give yourself a much better chance of determining whether or not a plant has a nutrient deficiency or excess and which particular element may need bumping up or down in feeds (more often than not once you’ve had to flush everything) to rectify the situation.

Now you know all of the elements that a plant needs to grow, the next step involves identifying the signs of deficiency and excess relating to each of them and the correct course of action to take if a problem emerges. Article 2 in the "Food For Thought" series will solely focus on the Primary Macronutrients (large amounts used by plants), covering in great detail the uses within the plant, level of mobility, nutrient deficiency symptoms and remedies and excess nutrient symptoms and remedies for Nitrogen (N), Phosphorous (P) and Potassium (P).