Burnt Grass & Fertilizer

To avoid burnt grass, it is best to understand how it happens. In fact, burnt grass is not a burn at all. It is the dehydration of grass as a result of over-fertilization. Too much fertilizer causes a lawn to absorb the salts in the fertilizer, causing a lawn to become dehydrated and dry out. This phenomenon is called "fertilizer burn."

New Grass vs. Old Grass

One of the most important characteristics of a healthy lawn is a healthy root system. As a lawn matures, the root system becomes stronger and more active. A strong and active root system also means a lawn is better able to cope with adverse conditions like over-fertilization. Owners of lawns with newly planted grass should use extra precautions when fertilizing since the new root systems are more likely to fall prey to over-fertilization and fertilizer burn. A young lawn does not have the hearty root system to combat the salts that build up with over-fertilization.

The same concept is also true for sod that has recently been laid down. When sod is transported, the root system of the sod experiences a certain amount of shock. This shock makes the sod more susceptible to adverse conditions.

Inorganic Fertilizers

Inorganic fertilizers are fertilizers that use nutrients that are not derived naturally. Inorganic fertilizers usually contain a mixture of ammonium phosphate, potassium chloride, ammonium nitrate, and potassium nitrate. These chemicals are immediately absorbed into the root system along with the present fertilizer salts. The quick absorption of salts makes the lawn more susceptible to fertilizer burn.

Organic Fertilizers

Organic fertilizers are fertilizers made of naturally occurring elements with a carbon structure. Common examples of organic fertilizers are plant refuse, manure, and sewage sludge. This type of fertilizer is not immediately absorbed by a lawn. The compounds in the fertilizers need to be hydrated and need time to decompose before being absorbed by a lawn. Because it takes longer for a lawn's root system to absorb the naturally occurring salts in organic fertilizers, the lawn is less likely to experience fertilizer burn when compared to inorganic fertilizers.

Time of Year

Regardless of the type of fertilizer you decide to use on your lawn, fertilizing a lawn during the summer months greatly increases the chance of a lawn experiencing fertilizer burn. Naturally occurring bacteria remain dormant in soil throughout most of the year. During the warm months of summer, the bacteria begins to multiply at a rapid rate, releasing significant amounts of nitrogen. The additional nitrogen from fertilizer can cause a lawn to suffer nitrogen burn, a form of fertilizer burn. It is best to fertilize a lawn during the colder seasons and in the evening.

Fertilizer Spreaders

One of the best ways to avoid over-fertilization, the cause of fertilizer burn, is to use a fertilizer spreader to ensure an even spread of fertilizer on your lawn. There are two types of fertilizer spreaders. Gravity spreaders are hand-held devices with a crank. With the fertilizer placed in the device, the crank is turned to activate an agitator inside. The agitator mixes the fertilizer and the fertilizer is then dropped from an open slot on the bottom of the device. Centrifugal spreaders spin rapidly, spreading the fertilizer from the sides of the device.

References

• ImproveYourGardenSoil.com: Avoiding Fertilizer Burn
• Plant-Care: Lawn Fertilizer Burn -- Don't Let It Happen To Your Yard
• PlantAnswers: Lawn Fertilizers