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Fertilizer & Lime for Beginners

Everyone wants a beautiful lawn or a healthy garden throughout the season and, 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.

What is fertilizer? 

Fertilizer is an amendment added to provide plants with necessary nutrients.

Most fertilizers contain three macronutrients:

  1. Nitrogen, which helps plants to grow and is always required regardless of soil test results.
  2. Phosphate, which helps plants use energy to grow.
  3. Potassium, which helps plants resist disease, withstand wetness and grow roots.

How can one tell what nutrients are in a bag of fertilizer?

A bag that lists 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 if 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. 

What is lime?

Lime is also an amendment that can be applied to the soil to increase the soil pH. It is made up of calcium and/or magnesium carbonate with small amounts of other minerals.  Lime products are among the oldest materials that are extracted from quarries and underground mines. 

Why is lime used on the soil?

The purpose of lime in the lawn or garden is to reduce the acidity levels in the soil by raising its pH. Soil test results provide the laboratory pH. Soils can be acidic, neutral or alkaline. A soil with a pH below six is considered acidic. Neutral soil is considered seven, and anything above seven is alkaline. Lime is used to raise the pH of a soil from an acidic level toward neutral. Most plants grow and can use nutrients when the pH is more neutral (seven).   

Healthy lawns and gardens can be achieved by following the recommendations provided by the soil test results. Proper application of fertilizer and lime will help ensure productive and healthy plants.

Author: Brian Sparks, WVU Extension Agent – Fayette and Nicholas Counties

Last Reviewed: August 2023