Fall is the season to renew your lawn. Earlier this month, I advised you that lime is the best treatment you can give to your lawn. Now, I’m cautioning you that fertilizing your lawn may well be counterproductive.
If you have been applying conventional lawn fertilizers for years, most likely you are wasting your money and contributing to the pollution of the Bay.
Lawn grasses require very little phosphorus (P) as compared to nitrogen (N). A single application of potassium (K) every two to three years is adequate to supply the needs of most lawns unless yours is growing on a very loamy sand soil. A medium level of P and K is all you need to keep your lawn growing green.
However, you won’t know whether you can save money on your fertilizer bill until you have your soil tested.
If your soil test results indicate that you have high to very high levels of either P or K, chances are you are contributing to the addition of these elements in the Bay by either surface runoff or the leaching of K into the groundwater and into the Bay.
High and very high levels of P in your soil could also be responsible for making iron, zinc, molybdenum and copper, among other nutrients, unavailable to the roots of plants. Excess P is known to fix these essential plant nutrients as well as calcium. Excess levels of P have been demonstrated to stunt plant growth.
Most likely, all your lawn needs is N, which is available in numerous forms. Urea is 46 percent N; ureaform is 38 percent N in a slow-release form; ammonium nitrate is 33-1/2 percent; ammonium sulfate is 21 percent; calcium nitrate is 151⁄2 percent; dried blood is 10 percent.
You won’t know which of these fertilizers to use until you have your soil tested.
Soil Testing Made Easy
I recommend A&L Eastern Laboratories Inc. Visit www.al-labs-eastern.com for details on the tests available, how to take the soil samples and how to prepare them for mailing.
In most cases the S1 test is adequate, but if your lawn is growing on a sandy soil, it is advisable to have the S3 test. If your lawn is located near the waters of the Bay or ocean, I recommend the S2 test.
If you air-dry the soil samples prior to mailing, you should receive your results within five working days. If you provide your e-mail address, it will take even less time.
If you provide them my e-mail address for making recommendations, they will send me the results and I will forward to you my recommendations.
For a good healthy lawn, consider having your soil tested every three to four years. Farmers are required to submit soils for testing every three years, as part of nutrient management. If I had my druthers, every home gardener would have to provide soil test results to purchase lawn and garden fertilizers.
A&L Eastern Laboratories Inc., 7621 White Pine Rd., Richmond, VA 23237; www.al-labs-eastern.com.
Find the Bay Gardener’s Sept. 8 column on line at bayweekly.com/articles/regulars/the-bay-gardener-by-dr.-frank-gouin.
Ask Dr. Gouin your questions at [email protected] All questions will appear in Bay Weekly. Please include your name and address.