Primary Nutrients (N-P-K)
Macronutrients: nutrients needed in large amounts
Nitrogen (N)
Nitrogen is the element, which stimulates aboveground growth and produces
the rich, green color characteristic of a healthy plant.
Excess will cause delaying maturity or ripening of the crop, lowering its
quality, lodging, and decreased resistance to disease.
Nitrogen is an important element that must be used in a balanced ration with
the other plant foods.
The most common source of Nitrogen is from organic matter (ex. Manure)
and commercial fertilizers.
Soils are generally 0.1% Nitrogen, so if not replenished, the soil will be
depleted by continual cropping.
Nitrogen leaches and adds to the depletion.
Nitrogen from organic matter is not available until the organic matter is
eaten by bacteria and converted into nitrite.
Nitrogen deficiency shows signs of yellowing on the leaf tips and along the
midrib of the leaf. Nitrogen is mobile in the plant, moving from the older
portion of the plant to the newer growth when in short supply.
If all the leaves are green, this means too much Nitrogen was used. If more
leaves are brown, this means not enough Nitrogen was applied.
Phosphorus (P)
Phosphorus is necessary for the hardy growth of the plant and activity of the
cells. It encourages root development, and by hastening the maturity of the
plant, making the plant more disease resistant.
It plays an important part in increasing the palatability of plants and
stimulates the formation of fats, convertible starches and healthy seeds.
In low pH soils Phosphorus is bound in a form unavailable to plants.
Phosphorus moves very little in the soil. Inert.
Potassium (K)
Potassium (Potash) has much to do with the tone and vigor of plants,
encouraging development of healthy root systems.
It is essential for starch formation in the plant and the development of
chlorophyll by encouraging photosynthesis.
pH is important for growing plants to take up potassium and if the soil is
very acid there will be a lack of Calcium, which is important for uptake of
Potassium.
Potassium moves very little in the soil.