Turfgrass and Water Quality
As an ever increasing proportion of our society resides in urban and suburban areas, there is a corresponding increase in the amount of paved and other impervious surfaces. Consequently, large amounts of poor quality storm water runoff are quickly channeled to storm sewer systems that dump directly into nearby lakes, streams and rivers. This can significantly contribute to decreased water quality in the receiving water bodies through sedimentation and pollution. Lawn grasses provide one of the most effective groundcovers available to prevent erosion and increase water infiltration into the soil.
Research over the last twenty years has demonstrated that storm water runoff from a healthy, dense lawn growing on soils of even moderate compaction rarely occurs, even on modest slopes. In fact, in all but very intense rainfall occurrences, stormwater runoff from a healthy, dense lawn is at or near zero. However, some notable exceptions to this include very steep slopes, saturated soil conditions, severely compacted soils and frozen ground.
In a recently completed 3-year study conducted at the University of Minnesota it was shown that 66 percent of total runoff and 80 percent of the phosphorus transported in runoff occurred while the soil was frozen. From that same study it was also shown that runoff increased as turfgrass quality and growth declined. Thus, a healthy, dense stand of turfgrass reduced runoff and thereby reduced phosphorus transport even when no additional phosphorus fertilizer was applied (Bierman, P.M., et.al. 2010)1.
The dense matrix of grass shoots, stems and leaves of an actively growing, healthy lawn significantly slows down any runoff that might occur, thereby increasing potential water infiltration. Slower moving runoff also has reduced capacity to carry sediment or other soil particulate matter, hence reducing the erosive effects of faster moving water. Not only does increased water infiltration help protect surface water quality; it also helps recharge groundwater supplies. The dense, fibrous network of roots help trap and remove nutrients and other pollutants from water moving down through the soil. This filtering effect can actually improve water quality as it moves through the turfgrass root zone.
Proceed to Turfgrass and the Soil Environment.