Objective: Students will identify how to interpret fertilizer labels. What is fertilizer? A material applied to supply essential elements Major Ingredients 1. Most commercial fertilizers have 3 numbers on the front label, separated by dashes. For example: 2. This is the fertilizer analysis or percentage by weight of the 3 major nutrients plants need: nitrogen, phosphorus and potassium, in that order. 3. These are abbreviated as N-P-K. If you purchased a 10 pound bag of fertilizer labeled 5-10-5, it would contain
5% nitrogen 10% phosphorus 5% potassium. The remaining 80% could be comprised of other nutrients and filler. 1st Number = Nitrogen 1. The first number gives the concentration of nitrogen in the product. 2. Nitrogen encourages foliage growth and general greening of the plant, among other benefits. 3. A fertilizer would contain 5% nitrogen by weight. 2nd Number = Phosphorous
1. The middle number refers to the concentration of phosphorous. 2. Phosphorous contributes to many fundamental plant processes such as rooting and setting flower buds. 3rd Number = Potassium 1. The final number states the concentration of potassium. 2. Potassium contributes to the overall health and vigor of plants. Complete Fertilizers 1. Fertilizers that contain all three major nutrients are considered complete fertilizers. 2. There are specialized fertilizers which are called incomplete because they lack one or more major nutrients such as a fertilizer labeled Reading a Fertilizer Label
P- 5 % K- 11 % Remaining 60% is other nutrients and filler. Analyze This! What do you know from the bag?
P:6 % K:12 % Use: Lawn Fertilizer Check for Understanding
Jack and Jill went up the hill and noticed the grass was very yellow. Which fertilizer would be best for them to use and WHY? Nitrogen is used to help promote lush green foliage growth, the fertilizer is the highest in nitrogen.