Every year, manufacturers recycle millions of pounds of tires into rubber mulch. Rubber mulches are longer-lasting than their traditional wooden counterparts; They're popular in part because they resist erosion. However, opinions vary on which mulch is superior. Cost, safety and appearance are all factors in the debate. Choose carefully and enjoy the right mulch for your landscape.
According to a 2009 Alabama Cooperative Extension article, covering 100 square feet 2 inches deep with rubber mulch costs $110, while a basic wooden mulch costs $45. However, the rubber mulch would save the homeowner $150 over five years in replacement costs.
Rubber mulches do not break down as quickly as wood mulches. Some rubber mulch manufacturers include a 10-year warranty. Wood mulches decompose and require replacement or renewing. In addition, wind and water often wash away wood mulches, but the heavier rubber mulches remain in place.
Manufacturers dye rubber mulches in a range of colors, including blue, orange and green, while wood mulches usually reflect the natural color of a type of wood. Rubber mulches also retain their color longer; for 32 weeks, according to Consumer Reports, which exposed both rubber and cedar wood mulches to the elements. Wood mulch and one brand of rubber mulch faded, while a second rubber mulch brand did not.
Fire burns longer in rubber mulches, states Consumer Reports, and the fire is more difficult to extinguish. When used under swingsets and on playgrounds, however, rubber mulch provides greater cushioning than wood mulch, although it may retain stray pieces of wire. Wood mulch often slivers or has other sharp angles. According to a Public Employees for Ethical Responsibility (PEER) report, the EPA released internal memos listing concerns regarding the toxicity of rubber mulch used on playgrounds. The EPA notes that the rubber crumbs leached heavy metals into the ground and released volatile organic compounds (VOCs) into the air. PEER also noted that children have extended contact with the rubber mulch on playgrounds and that the rubber's chemicals may be absorbed through the skin.
Although recycling materials reduces environmental waste, mulch made from shredded tires introduces toxins into the soil. According to Fine Gardening, rubber mulches release heavy metals as sunlight and bacteria break the rubber down. Polyaromatic hydrocarbons and other carcinogens also leach into the soil. Vegetables absorb and concentrate these heavy metals, transferring the toxins to individuals when eaten. Alternatively, wood mulches break down into beneficial soil amendments.