As our grass has been growing and we have been mowing like crazy, the Orleans County Cornell Cooperative Extension receives calls from people interested in eco-friendly lawn care practices. To be most successful with this you need to focus more on mowing and less on fertilizing according to Cornell turf specialists.

I would like to share with you a recent article from Dr. Marty Petrovic from the Department of Horticulture at Cornell University, who cites his experiences with the dangers of over-feeding and a concern for phosphorous pollution. He also lists his lawn care preferences which we can easily integrate into our own practices.

The first step

The first step to minimizing the environmental impact of your home lawn is to raise the mower’s blade to a height of three to four, which is usually the highest setting on your mower. Then let the grass clippings remain on the lawn.

Taller grass competes better against weeds and allows roots to grow deeper into the soil to better withstand the heat and drought of summer. This promotes a thicker turf with fewer weeds and requires less watering.

It is also advantageous to keep your mower blades sharpened for a cleaner cut which will not shred the grass tips.

By leaving the clippings lay on the lawn, it recycles nutrients so less fertilizer is required. Petrovic’s research shows that it’s likely most lawns in the state do not need any additional phosphorus fertilizer especially if the clippings are not removed.

Prevent fertilizer pollution

Petrovic has been studying the fate of phosphorus fertilizer applied to lawns. When too much phosphorus washes into lakes and streams, it can contribute to algae blooms, eutrophication and a reduction in water quality.

Fortunately, phosphorus is a relatively insoluble, immobile nutrient. Most of this nutrient from yards that ends up in surface waters gets there when water runoff physically carries away eroded soil or plant material including leaves and grass clippings.

An important step in preventing phosphorus pollution is to make sure your turf is thick enough to keep soil from washing and to be cautious with clippings and leaves. It is critical that you not blow the grass clippings or leaves into the road, ditches or storm water drains. In addition, sweep clippings from your drives or walks.

Whether you use organic or chemical fertilizers do not spread them on hard surfaces, and promptly clean any spills. Also avoid applying fertilizer to areas where the soil is always wet because these areas are more prone to runoff.

When Petrovic analyzed the results of soil tests sent to the Cornell Nutrient Analysis Laboratory for lawn fertilizer recommendations, he found that about 80 percent had enough phosphorus already. His research may lead to lowering the level of phosphorus considered to be adequate for home lawns.

His recommendation is to scout around for zero-phosphorus fertilizers to use.

Petrovic’s concern is that some lawn owners who want to use eco-friendly lawn care practices will over-apply organic products, especially those made from composted animal manures, most of which are relatively high in phosphorus.

No doubt, the organic matter in such applications are good for soils low in organic matter. However, the tradeoff comes in excessively high levels of phosphorus in the soil with pollution potential.

If you want the benefits of organic matter but are concerned about phosphorus, consider yard waste composts which are generally lower in phosphorus than most manure products, Pertrovic advises.

Green up

Even if you have enough phosphorus as indicated by a Cornell lab analysis, and return clippings to the soil, your lawn will still require nitrogen to help create the kind of dense turf that helps prevent runoff. If you do not want to use zero-phosphorus chemical fertilizers, Petrovic suggests using organic nitrogen such as corn gluten.

Fall and late spring, around Memorial Day, and not early spring, are the best times to apply nitrogen.

Other eco-friendly practices recommended by the Cornell turf specialist include improving watering customs and not attempting to grow grass in areas where it simply will not grow. Consider planting shade-loving plants where too little light exists to support lawn growth. Consider rain gardens where drainage is poor. Consider adding “hardscape” for areas of high foot traffic.

For more lawn care information, contact Orleans County Cornell University Cooperative Extension at 798-4265, ext. 35.

Dave Reville is an Extension horticulture educator at the Orleans County Cornell Cooperative Extension.