Green lawns -- green lakes

Using lawn fertilizers with phosphorus not only greens up lawns, it also can make our lakes green in the summer.

Phosphorus is a nutrient that promotes root growth and green foliage. Most Minnesota soils, Crow Wing County included, are naturally high in phosphorus. As a result, if the lawn contains extra phosphorus it can be washed into lakes and streams, where it contributes to algae growth, decreased water clarity, diminished oxygen for fish and aquatic life, and undesirable swimming, boating and fishing.

The best way to keep excess lawn nutrients from getting into the lake is not to fertilize at all. More grass means more time mowing the lawn instead of enjoying the lake.

However, if you must fertilize, look for zero phosphorus fertilizer. That's fertilizer with a middle number of zero (XX-0-XX) on the bag. Many area retailers carry zero phosphorus fertilizer. To find out if your soil needs phosphorus, stop by the Crow Wing County Extension or Soil and Water Conservation office for a simple, inexpensive soil sample kit. If the soil doesn't need phosphorus, don't apply it.

Soon homeowners will not have a choice about whether to use phosphorus fertilizer or not. A new law passed by the 2002 Legislature imposed a virtual ban on the use of phosphorus lawn fertilizers in the seven-county metro area beginning January 2004. The law requires that lawn fertilizer in the rest of the state contain no more than 3 percent phosphorus. It does not apply to crop or other agricultural uses. Area counties can adopt the stricter policy of using zero phosphorus lawn fertilizer. Crow Wing County is already discussing this option.

Another way to prevent phosphorus and other runoff from getting into your lake is to establish a buffer strip of natural vegetation at least 25 feet wide between the lawn and the lake. Find out more about buffer strips next week.

Use zero phosphorus fertilizer to keep our lakes clean, not green.

(Sponsored by the Crow Wing County Water Planning Task Force and the Minnesota Lakes Association.)