Everyone wants a beautiful lawn or a healthy garden throughout the season. To achieve that goal, one must follow several practices, such as preparing the planting site, providing adequate water, and applying fertilizers and lime following soil test recommendations.
Fertilizer provides plants with necessary nutrients. Most fertilizers contain three macronutrients: nitrogen, which helps plants to grow and is always required regardless of soil test results; phosphate, which helps plants use energy; and potassium, which helps plants resist disease, withstand wetness and grow roots.
When using fertilizer, we must figure out what quantity of nutrients are in a bag of fertilizer. A bag that is labeled 10-20-20 contains 10% nitrogen, 20% phosphate and 20% potassium.
Applying this concept, a 50-pound bag of 10-20-20 fertilizer would contain 5 pounds of nitrogen, 10 pounds of phosphate and 10 pounds of potassium. The other 25 pounds of material in the bag of fertilizer is filling material. Respectively, the numbers represent percentages not pounds.
Another example would be a 40-pound bag of 10-10-10 fertilizer contains 4 pounds of nitrogen, 4 pounds of phosphate and 4 pounds of potassium, with 28 pounds of inert material.
Fertilizer can contain additional micronutrients that are essential to plant growth and health, which will be listed as an additional component on the outside of the bag. It is important to read the outside of the bag and to match nutrients contained in fertilizer with the soil test analysis.
By Brian Sparks, WVU Extension Agent – Fayette and Nicholas Counties