Ron Struss, Regional Extension Educator, Farmington, 651-480-7708

Have you bought your first bag of phosphorus-free lawn fertilizer? Was it easy to find, or was the store clerk befuddled when asked for lawn fertilizer with a “zero in the middle?”

Since January 2004 in the Twin Cities metro area, and January 2005 in the rest of Minnesota, the use of phosphorus lawn fertilizer has been restricted. For everyone except sod farms and golf courses the law is straightforward: Do not use lawn fertilizers containing phosphorus unless your soil is low in phosphorus or you are seeding a new lawn. The law is for water quality protection; the nutrient phosphorus spurs growth of algae in lakes and rivers.

The new law presents two challenges for those caring for lawns: 1) Finding phosphorus-free lawn fertilizer, and, 2) knowing whether your lawn is low in soil phosphorus. The first challenge of finding phosphorus-free fertilizer has been solved in the Twin Cities metro area. It is difficult to find a store selling lawn fertilizer that does not offer a good selection of phosphorus- free products, including “weed & feed” combinations. It is anticipated by next season the same will be true state-wide after old fertilizer stocks are depleted and new orders are adjusted for 2006.

As for knowing whether a lawn is low in soil phosphorus and in need of phosphorus fertilization, soil testing provides the best answer. Both private laboratories and the University of Minnesota offer soil testing for lawns. Contact your local agricultural supply store for laboratory names, or the University of Minnesota Soil Test Lab at 612-625-3101. A soil test costs about $15.

For additional information on the Minnesota Phosphorus Lawn Fertilizer Law, go to the Minnesota Department of Agriculture’s Web site look under “Lawn Care and Water Quality.” Also, educational material on lawn care and water quality is available in the “Tools” section of http://www.cleanwatermn.org.

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