Technical Bulletin No 8: The Clipping Point
Three independent methods are used to estimate the extent of turf cover in the Chesapeake Bay watershed and data from previous studies is cited to estimate the potential environmental management implications of turf grass.
The three methods include:
- GIS based approach using moderate-resolution satellite derived land cover data
- pro-rated state turf industry statistics
- coarse-resolution satellite derived regression equations.
The methods, which represent different base years from 2000 to 2005, suggest that turf cover ranges from 2.1 to 3.8 million acres, or 5.3% to 9.5% of total Bay watershed area. Approximately 75% of current turf cover is potentially devoted to home lawns. In Virginia, data indicate that turf acreage grew faster than population or impervious cover in the last three decades with an annual growth rate of 8%. Turf cover arguably constitutes the single largest fraction of pervious area in the watershed, exceeding the total individual acreage devoted to row crops, pasture, hay/alfalfa or freshwater wetlands, respectively.
The potential impacts to the Bay due to turf cover are expressed in terms of annual biomass production, nitrogen fertilization, pesticide application, water use, runoff from compacted soils, energy use, carbon sequestration, VOC emissions and the cost to maintain such a large fraction of watershed area as a grass crop. Although much more needs to be learned about turf management practices in the Bay watershed, initial estimates suggests that turf has a strong influence on water quantity and quality in the Bay watershed.
Despite the large size of the turf sector in the Bay watershed, it only receives a small fraction of the resources, funding and technical assistance devoted to managing other nutrient sources, such as agriculture, wastewater, and forestry. An estimated 6.1 million “turf grass farmers” exist in the watershed who currently spend nearly 5 billion dollars a year (including more than $600 million expended alone for fertilizers and chemicals). By changing their attitudes and behaviors about what constitutes a green lawn, it may be possible to achieve major runoff and nutrient reductions to the Chesapeake Bay.