You see on fertilizer bags and information things like 25-0-4 and 10-0-10. But what do those fertilizer numbers mean, and what do they mean for my lawn? The lettered abbreviation for those numbers are NPK. Now that doesn’t help without more explanation.
- N stands for nitrogen and it is one of the main elements that helps grass grow. This is always the first number listed. Nitrogen is helpful in creating leaf blade growth for the grass plant. Nitrogen is also an important element needed for the grass plant to produce chlorophyll. This is why it is most of the time the largest number in the fertilizer analysis.
- P stands for phosphorus. This is always the second number listed. It was once included in more fertilizer than it is now. Phosphorus helps to improve the vigor of the grass plant. However, it is not generally included in fertilizer anymore; Michigan has banned it from being in fertilizer in most circumstances. This is because most Michigan soils have plenty of phosphorus in them, so the soil does not need anymore. If your soil does need phosphorus, in Michigan, you can apply phosphorus if you have a soil test proving your soil needs to have it added. The phosphorus that was being applied with fertilizer would generally end up in the waterways, and help to produce algae blooms in the areas water.
- K stands for potassium, which helps grass plants to grow better root systems. This is always the last number listed. Potassium is generally applied in some amount throughout the growing season, but in the fall, larger quantities are typically used. This is because you want the roots to become hardier to be prepared for the winter season. Then when spring comes, the grass plant will be better set to start growing again.
The number for each element is listed as a percentage. To list what fertilizer is best for every lawn is impossible. Fertilizer should be tailored to each individual lawn to provide it with the proper nutrients that it needs.