The Meaning of Fertilizer Numbers & Types of Fertilizers

Helping you fertilize properly.

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The basic fertilizer mixture discussed here is the n p k base; N=nitrogen, P=phosphorus, and K=Potassium. The way to understand the fertilizer ratio numbers is that the first number is always nitrogen, the second is always phosphorus and the third is always potassium. If the number reads 10-10-10 or 8-8-8 it simply means an equal amount of each ingredient is present in the mix. To determine the actual percentage of minerals in a fertilizer you simply add the numbers together. Thus a 10-10-10 fertilizer will consist of 30% fertilizer minerals by bag weight with the remainder of ingredients being other trace minerals and fillers. Fillers are added to help with spreading as well as to keep dry fertilizer from hardening.

For example a bag of a 50 Lb bag of 10-10-10 fertilizer would provide 5 lbs of nitrogen, 5 lbs or phosphorous and 5 lbs of potassium - N-P₂O₅-K₂O.  Your best bet is to get a soil test to determine the amounts of nutrients, if any, your soil may need. Some areas of the USA have nutrient surpluses such as phosphorous that occur naturally in the soil. Over fertilization can damage or kill your grass lawn or plants in addition to ruining your soil and polluting local water supplies.

Basic Plant Fertilizer Ingredients

N - Nitrogen

Nitrogen promotes foliage and overall growth. It is also responsible for the darker green color you see when some grasses are fertilized with nitrogen -- this is not to recommend overloading your lawn with nitrogen!

P - Phosphorus

Phosphorus promotes root development. This is important for lawn and pasture grasses to develop drought tolerance.

K - Potassium

Potassium promotes diseases resistance and aids in the production of flowers and fruit.

Additional Minor Fertilizer Ingredients

Magnesium
Calcium
Sulfur
Iron
Manganese
Zinc
Boron
Molybdenum

INERT INGREDIENTS:
The remaining contents of the fertilizer contains fillers that help keep the fertilizer from hardening into chunks keeping it in a loose usable form easier for spreading. In storing fertilizer for lawn and garden purposes it is easy for the fertilizer to collect moisture and become hard and more concentrated and must be broken into fine particles for distribution. The more concentrated it becomes the harder it is to apply correctly without burning the plants.

Types of Fertilizers

Commercial fertilizer basically is produced and marketed in 3 forms. They are dry, soluble and time released...

Dry is your standard dry fertilizer. Soluble fertilizer is easily dissolved in water. Time released fertilizers are coated dry versions that slowly dissolve over a period of time. Seeds and new plants need a fast acting fertilizer to get them off to a good start and to establish the strongest root system in place.

Time released fertilizers are best used after plants have started growing because of the slow release time provides a constant rate of food over a longer period of time and will not leach away like the other fertilizers may be by over watering or increased rains.

Slow releasing fertilizers appear to be higher in price but they can last up to three months. They are easy to use and will not burn the grass, flowers or gardens and don’t need mixing in water or scheduled weekly or monthly for use.

Soluble fertilizers are easy for people that like to feed weekly or monthly and water by hand. These are mixed according to the directions for the best results.

Select the proper fertilizers for your project and plants based on soil tests!

Tips For Fertilizer Usage

Adding a high level of any one fertilizer mineral ingredient at the wrong time or the wrong amounts may result in plant death, stunted growth, and make flowers or fruit actually fall off. It is highly recommended that you have a soil test done before you fertilize or plant your lawn or other plants. The results of a soil test should give you a good idea of what -- if any -- amendments or fertilizer are required and the amounts that you should use. You should also consider the type of plants or lawn you plan to grow and it's  particular mineral needs. Your local Extension Agent or University Agricultural Extension Department should be able to assist with testing your soil.

Follow instructions! Occasionally extra amounts of one ingredient may be needed over another or left out of the equation all together. For example centipede grass can become iron deficient. Adding extra nitrogen will only deplete the iron in the soil more. Iron should be added before additional nitrogen.

Organic Fertilizers

Organic fertilizers are fish emulsions, Milorganite® (treated sewage product), composts and any other natural non-chemical additives such as animal and green (plant) manure's. These organic fertilizers can be used in conjunction with natural amendments to soils such as your grass clippings and with good organic growing practices. Organic fertilizers are becoming more popular as people realize that chemical fertilizers are not the safest for us, our children and the environment.

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