Leaves, tree limbs, grass clippings, and other forms of yard, garden, and land-clearing refuse often account for up to 20% of landfill waste. For this reason, many states have banned the dumping of such yard, garden, and land-clearing waste into their solid waste landfills. Composting is seen a one alternative to dumping by recycling these organic trimmings so that they can be reused to condition garden and landscaping soil.
What is Composting?
Composting is a biological process where microorganisms are used to decompose leaves, twigs, grass clippings, manure, and food wastes into organic matter called compost that no longer resembles its original form. Composting utilizes the same process that occurs naturally in nature where microorganisms decompose leaves and other organic matter, only composting accelerates the decomposition process by controlling the conditions.
Aerobic vs. Anaerobic Composting
Aerobic composting utilizes microorganisms that require oxygen. Those organisms require at least 5% oxygen in the composting pile. For comparison, oxygen makes up about 21% of “fresh air.” Microorganisms used in anaerobic composting prefer an absence of oxygen. Aerobic composting is preferred over anaerobic composting, because aerobic composting is faster and more efficient.
Mulching is the practice of adding leaves, grass clippings, compost, and other organic material to the surface of the soil. Mulching helps to hold in moisture, control weeds, reduce erosion, and regulate the soil temperature.
There are many advantages to composting. Not only does composting reduce the amount of refuse in landfills, but the compost material produced by this process can also be used to improve soil. When compost is mixed into soil, it does several things:
- It increases the percentage of organic matter in the soil
- It improves the physical properties of the soil (tilth, drainage, water, and nutrient retention, etc.)
- It supplies essential nutrients to help condition the soil
If yard trimmings are added directly to the soil, they will eventually decompose. However, doing so could rob plants of much needed nitrogen. The microorganisms that work to decompose such yard trimmings require nitrogen to do so, and would compete with plant roots for the nitrogen in the soil.