The Basic Essentials: Nitrogen, Phosphorus and Potassium (NPK)
By Cosmo MacKenzie • 3 weeks Ago
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By Cosmo MacKenzie • 3 weeks Ago
Nitrogen, Phosphorus and Potassium, commonly referred to as NPK, differ from most other nutrients in that they are able to move around a plant as needed. Understanding the part they play in the process of growing, and being able to read what they are doing will mean the difference between success and failure for your crop.
Keeping a keen eye on the health of your plants is essential to achieving a high quality crop. Regular checks, both visual and measured, will give you the best possible chance of catching and dealing with any problems before they get too severe.
“A lack of Nitrogen in your crop will inhibit a plant’s ability to produce chlorophyll. Growth rate will slow down and leaves will start to yellow…”
The Chemical element nitrogen (N) is thought to be the seventh most abundant in our Galaxy. 78.09% of Earth’s atmosphere is made up of nitrogen. It is contained in every living cell in the human body.
Plants use nitrogen to produce alkaloids, amino-acids, chlorophyll, enzymes and nucleic-acids. Chlorophyll is responsible for the process of Photosynthesis and the nitrogen it contains is responsible for the rich green colour visible in healthy plants. Relatively high levels of Nitrogen are particularly necessary during the vegetative growth stage of juvenile plants.
Plants naturally take nitrogen from decomposing organic matter in the soil.
An excess of nitrogen in your crop will lead to decreases in the growth rate, size and general health of your plants. Excessive nitrogen acts to debilitate a plant’s ability to utilise essential nutrients necessary for healthy growth. Plants suffering from toxic levels of nitrogen display stunted root systems and tend to be weak and spindly. They also suffer an increased susceptibility to diseases. Continued exposure to excessive levels of nitrogen will result in a crop heavy with dark green foliage bearing sparse and weak flowers and fruit. Too much nitrogen can kill your plants and, in high enough quantities, is hazardous to animal life (that means you!).
A lack of nitrogen in your crop will inhibit a plant’s ability to produce chlorophyll. Growth rate will slow down and leaves will start to yellow, particularly in the lower section of the plant, eventually dropping off.
A nitrogen deficient crop grows to be thin, frail and generally pallid. nitrogen washes away very easily, so it is especially important in hydroponics to regularly add nitrogen to any crop’s diet. The production of nitrogen based fertilizers is said to account for 1% of world energy production.
Flushing the roots and growing medium of your crop should help to bring down toxic nitrogen levels. Cutting the supply of nitrogen to your crop for a brief period should force plants to use up any excess nitrogen in the system. If the problem persist it is probably advisable to lessen the amount of Nitrogen provided to the plants.
Conversely, upping the nitrogen dosage to your crop should resolve any problems resulting from a nitrogen deficiency.
“Phosphorous deficiency commonly shows as a blue tint in the leaves, which eventually develop necrotic blotches, shrivel and die before dropping off.”
Phosphorus (P) is essential to nearly all life on Earth, being both a component of DNA and necessary in the production of cell membranes.
Phosphorus is a necessary component in Photosynthesis. It is responsible for the transference of energy between cells and stimulates the formation of convertible starches and fats in a plant. By encouraging rapid cell growth, phosphorus speeds the maturation process and increases disease resistance in plants.
Phosphorus encourages robust growth in plants. It is particularly important for healthy root development, higher yields and well-formed seeds.
Too much phosphorous can act to suppress the uptake of nutrients in a plant (namely calcium, iron, magnesium, copper and zinc) leading to a potassium deficiency. Toxic levels of phosphorous aren’t immediately evident and can be hard to diagnose. They usually display as a deficiency in one or many of the nutrients listed above.
Often caused by acidic soil, plants deficient in phosphorous produce lower yields; both rate and quality of growth are stunted. Phosphorous deficiency commonly shows as a blue tint in the leaves, which eventually develop necrotic blotches, shrivel and die before dropping off.
As with nitrogen, flushing the growth medium is an effective method for treating excessive levels of Phosphorous. Lowering the pH level of your growing medium should help in the treatment of a phosphorous deficiency, as should upping the potassium level through the use of specific feeds or fertilisers.
“Potassium deficiency in a plant is generally characterised by yellowing leaves and results in a notable retardation of flowering.”
Potassium (K) derives its name from Potash (plant ash) from which it was first isolated. Despite the fact that it accounts for 2.3% of Earth’s crust, potassium isn’t considered readily available to plants as most of it bound to other minerals.
Plants use potassium to produce amino acids, carbohydrates, starch and sugars as well as to transport them around the body of the plant. Potassium is also responsible for chlorophyll production, regulating turgor pressure and thickening cuticles. Turgor pressure regulates turgidity in cells which in turn help to keep the plant rigid and prevent it from wilting.
Potassium is utilised by plants at every stage of their growth, strengthening the plant against diseases, encouraging strong root growth and enhancing the qualities of any fruit produced by the plant.
Excessive levels of potassium aren’t easy to identify specifically. Toxic levels act to suppress a plant’s intake of iron, magnesium, zinc and manganese. Potassium poisoning is, thankfully, relatively rare.
Potassium deficiency in a plant is generally characterised by yellowing leaves and results in a notable retardation of flowering. Once again, flushing your growing medium will help to curb excessive levels of potassium, whilst feeding with the appropriate feed or fertiliser will act on any potassium deficiency.
Hormones regulate metabolism in plants and humans alike; learn about them here.
This article was originally published in Issue 001 of HYDROMAG (September – October 2012).
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