The days of ignoring the obvious are long gone... It is no longer acceptable or responsible to simply purchase any ol' bag of fertilizer, pull out the uncalibrated dusty spreader from the garage, and hope for the best. We must strongly question what, why and how we are applying fertilizers to our lawns in an effort to provide only what is needed for a healthy, attractive lawn without waste or disregard for our environment.
Upon first glance of all fertilizer packaging you will find three numbers in bold print. These numbers represent the percentage of Nitrogen, Phosphorus, & Potassium found within the contents of the product, otherwise known as N-P-K, always in that order. ?These nutrients are the three most abundant in every bag of fertilizer. As an example, a typical 50 pound bag of fertilizer labeled 30-0-10 should be viewed as 30% nitrogen, 0% phosphorous, and 10% potassium. So, a 100 pound bag of fertilizer that contains 30% Nitrogen would contain 30lbs Nitrogen. Keep in mind that bags are typically 50lb, so a 30-0-10 bag consisting of 30% Nitrogen actually represents 15lbs of Nitrogen, 50lbs x .3 = 15, for example.
Essentially, Michigan grass plants are in need of two of the three main nutrients: nitrogen and potassium. Nitrogen is what will give your lawn its rich, green color.? Potassium works to strengthen grass roots and to help your lawn ward off pests and disease. In other words, potassium gives your lawn a strong immune system! Plants are just like people - they need food to nourish them and by fertilizing your lawn, you are simply feeding it and giving it the energy it requires to thrive. ?
The phosphorus content that is listed as the middle number on any bag of fertilizer should be avoided and is ussually not nessesary as typical Michigan soils have ample amounts stored up within the ground. In fact, as of January 1, 2012, this nutrient must be listed as "0%", as it is now restricted from use on an established turf because of contamination concerns of watershed and leaching. Most soils in our area are naturally rich with phosphorus; therefore any additional phosphorus you apply is not used by the plant and simply runs off the lawn before penetrating the soil. That means it gets into the lakes and streams contributing to the blue-green algae bloom and growth of other undesirable aquatic plants. For this reason, as of January 2012, Michigan has instituted a statewide ban on the use of lawn fertilizer with phosphorus. The exception to the ban and reccomemded use is to include the nutrient on newly seeded lawns and where soil tests show it is needed.? This is especially true due to the strong relationship between Phosphorus and root production, aiding the young seedling to focus on root prodiuction in an effort to become established.?
Our lawn treatment program typically consists of three dry fertilization applications and one liquid fertilizer application with a combined total recommended Nitrogen application of 3lb-3.5lb of nitrogen per 1000 sq ft per season. Although not discussed in detail in this article, our complete lawn treatment package also includes two liquid application weed treatments (Spring & Fall) with the Fall treatment adding up to an additional .5lbs N per K of liquid quick release Nitrogen in early October.