What are plant-nutrients and why is it needed?
The usual estimate is that 16 subjects are necessary for all plants function.
Roughly, nutrients are divided into macro and micro nutrients.
For macro-nutrients counted Nitrogen, Phosphorus, Potassium, Magnesium and Sulfur (N, P, K, Mg and S) and Carbon, Calcium, Oxygen and Hydrogen. Among the micro-nutrients can be mentioned such as Boron, Copper, Manganese, Iron, Chlorine, Molybdenum and Zinc.
Additional elements are necessary, but only for certain plant species. Examples of such substances are Sodium, Cobalt, Nickel and Silicon. Nitrogen-fixing plants like clover, needs e.g. a supplies of cobalt, C4 plants (Maize,Sugar-Cane(need more energy=sun) are dependent on Sodium and Soybeans must be able to take up the Nickel. Nutrients have different functions in the plant. They affect cellular water balance, catalyze reactions in the plant, is necessary in the photosynthetic electron-transport and are the building-blocks for growth in e.g. amino acids, lipids and DNA.
Important to note is that ALL the nutrients is needed. Deficiency in just a single topic, can lead to various diseases as well as generally weaker growth and vitality of the plant. It is also true that the lack of a topic restricts the plant's ability to take advantage of other plant nutrients.
A small overview about each plant-nutrients function:
Macro-nutrients
Nitrogen (N)
Nitrogen is needed to build proteins in plant cells, ie more practical contribution to the growth or new shoots/sprout after pruning.
Nitrogen is normally the plant nutrient needed in greatest amount. All growth in the plant requires Nitrogen. Nitrogen also contributes to the green leaf color, since nitrogen is a major constituent of the chlorophyll molecule. Nitrogen is absorbed by the plant through the form of nitrate and ammonium ions. But these ions are also relatively volatile in the soil-solution and if the plant is fertilized with only nitrate and ammonium, the effect is very short-sighted. Instead, it is important that the nutrient that is supplied, partly containing of ammonium and nitrate for quick effect, but also more slow-acting nitrogen-forms such as Urea and ”polyurea”, that in the ground can be converted into forms that the plant can absorb.
Phosphorus (P)
Phosphorus is needed for seed set, but is also crucial for e.g. root-development. Phosphorus contributes to the infiltration and transportation of energy from photosynthesis. Phosphorus is relatively difficult-movable in the soil profile, the roots of the plant have to ”grow" to the phosphor. For this reason, it is imperative that phosphorus is available in the entire "deep soil" so that the roots are drawn there (Allgrow spreads phosphorus to the whole humus layer and deep-soil). Phosphorus is always important but perhaps most in the establishment phase.
Potassium (K)
Potassium is important for plant metabolism and helps the plant to prepare for "winter sleep". Potassium is also an important component in the plant's internal water transport. Lack of potassium leads to a greater risk of drought stress as well as winter damage.
Magnesium (Mg)
Magnesium is an essential element in chlorophyll and thus a prerequisite for a functioning photosynthesis and energy supply.
Magnesium and Potassium is important to control the water content in the plant. One should be aware of the balance between potassium and magnesium, as they compete with each other. A practical way to handle this, is to use a fertilizer with balanced Potassium / Magnesium-content (Allgrow have that).
Sulfur (S)
Sulfur is important for photosynthesis, but are also included in the amino acids, enzymes and hormones in the plant.
Micro-nutrients
Micro-nutrients have in common that they are needed in smaller amounts than macronutrients. At the same time, they are often critical to the plant's vital functions on metabolism and growth. Again, it is time to remind of Liebig's barrel (see article "Liebig - Humus Theory” above). If there is a shortage of any substance, the other ones can not be absorbed either.
Therefore, use fertilizers that are naturally complete - including micro-nutrients.