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What is NPK in Fertilizer?

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NPK is an acronym used to describe Nitrogen (N), Phosphorus (P), and Potassium (K) levels in fertilizer. NPK are the three primary nutrients needed for plant growth.

The three numbers on a bag of fertilizer – for example, 4-6-4 – represent the ratio (by percentage) of each nutrient. They are always in order as NPK. In the case of 4-6-4, the percentage is 4% Nitrogen, 6% Phosphorus, and 4% Potassium. In total, this equates to 14% (4% + 6% + 4%) of nutrients contained in this fertilizer and 86% of minor nutrients.

Conclusively, plants need around 16 nutrients to remain healthy, such as calcium, iron, and chlorine. Some nutrients are also passed on to soil and plants via air and water.

Nitrogen

Nitrogen is the first part of NPK. It plays a key role in plant coloring and chlorophyll production – making it an important factor in leaf development. High-nitrogen fertilizers are used for grass and plants where green foliage is more crucial than flowering.

How do I know if I might have a Nitrogen deficiency?
When grass or other plants are yellowing (starting with the youngest leaves), this can be a sign of nitrogen deficiency. However, it can also be a sign of too much Nitrogen. A soil test is crucial when you are at a crossroads.

Phosphorus

Phosphorus is the second part of NPK. It plays a key role in root development, seed formation, blooming, and fruiting. It’s essential for plants, particularly in the spring.

How do I know if I might have a Phosphorus deficiency?
If leaf or blade tips are brown and dying, this could indicate a Phosphorus deficiency.

Potassium

Potassium is the third and final part of NPK. It plays a key role in the overall vigor, health, and growth of plants. It strengthens a plant’s ability to resist disease and pests and strengthens a plant’s ability to absorb water and nutrients. Potassium is particularly important in climates that are cold and/or dry.

How do I know if I might have a Potassium deficiency?
If leaf margins on older leaves turn bright yellow and look scorched, or you find brown speckles covering your leaves or blades, you may have a Potassium deficiency.

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