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Nitrogen
(N) |
Nitrogen is a major component of plants; it is a
building block of amino acids, proteins, and nucleic acids
(genetic material), chlorophyll, and enzymes.
Though nitrogen is in air, it is only available to
plants once it has been fixed by soil microorganisms.
Without an adequate supply of nitrogen appreciable
growth cannot take place and that plants may remain stunted and
relatively undeveloped when nitrogen is deficient
Nitrogen deficiency causes an overall yellowing of
the plant with the lower leaves yellowing and dying from the leaf
tips inward.
Deficiencies can be remedied by adding manure,
compost, urea, seed meal, or blood meal. Leguminous cover crops
will also supply nitrogen |
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Phosphorous (P) |
Phosphorous is important in cell formation so is most
needed by the growing parts of the plant. It also helps make your plants
more resistant to disease.
Unlike nitrogen, Phosphorus doesn't dissolve so soil will
hang onto phosphorus, not releasing it into water. To make sure your
plants get the proper amount of phosphorus, mix it deep into the soil so
roots can reach it.
Because Australian soils are deficient in Phosphorous,
most plants have evolved to handle low levels of this element.
Accordingly, fertilisers rich in Phosphorous should always be used
sparingly around natives.
A phosphorous-deficient plant is usually stunted,
thin-stemmed, and spindly, but its foliage is often dark, almost bluish,
green. Thus, unless much larger, healthy plants are present to make a
comparison, phosphorous-deficient plants often seem quite normal in
appearance. In severe cases, phosphorous deficiency can cause yellowing
and senescence of leaves
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Potassium (K) |
Potassium is necessary for the formation of sugars,
starches, carbohydrates, protein synthesis and cell division in
roots and other parts of the plant. It is crucial for most growth
factors including photosynthesis, metabolism, and plant resistance
to disease. Potassium greatly influences fruit and vegetable
quality.
Plants require more potassium than any other
nutrient but nitrogen.
Potassium deficiency is relatively easy to detect
compared to deficiencies in phosphorous. The tips and edges of the
oldest leaves begin to yellow (chlorosis) and die (necrosis), so
that the leaves appear to have been burned on the edges |
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