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Fertilizer label and application rate PDF Print E-mail
Thursday, March 28, 2013 11:44 AM

Extension Educator OSU-Extension, Paulding

All fertilizers will have a series of three numbers displayed prominently on the label. These numbers represent the percentage by weight of nitrogen, phosphorus, and potassium. For instance, a 24-4-8 fertilizer will have 24 percent nitrogen, 4 percent phosphorous as P2O5, and 8 percent potassium as K2O. A 46-0-0 fertilizer will have 46 percent nitrogen and no phosphorous and potassium.

Though all three elements are important in maintaining a healthy turf stand, nitrogen will cause the greatest response. Because of this, most fertilizer recommendations for lawns are listed as pounds of nitrogen per 1000 square feet.

If late fall fertilizer was applied last October or November, then make only one fertilizer application this spring, preferably in late April or early May, using no more than ¾ pound actual nitrogen per 1000 square feet. If a late fall fertilizer was not applied, then make two applications this spring; the first application in early April, the other in mid to late May using 3/4 pound actual N per 1,000 square feet each time.

Fertilizing with phosphorus and potassium is also important in maintaining a healthy lawn. The best way to determine how much phosphorus and potassium to apply annually is to follow the recommendations of a soil test. In lieu of a soil test, a general recommendation is to apply 1/4 as much phosphorus and 1/2 as much potassium as nitrogen. For a one year fertilization cycle, if you apply 4 pounds nitrogen per 1000 square feet per year, you should apply 1 pound phosphorus and 2 pounds potassium per 1,000 square feet per year.

It is best to fertilize lightly in spring and early summer, little to none in summer, and heavy in fall. A heavy fall fertilization program will produce the healthiest turf throughout the year. Applying high rates of nitrogen in the spring and summer stimulates excess leaf growth at the expense of root growth. Not only does this force you to mow more often, it reduces turf quality during the summer. High application rates of spring and summer nitrogen can also stimulate disease, weed, and insect activity.
If you apply a pre-emergence herbicide that is combined with fertilizer in April, the May fertilizer application should be skipped. Professional lawn care companies may increase the number of applications while decreasing the rate of nitrogen per application. This can give a more gradual feeding of the grass plants and produce a high quality lawn.


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