Today's environmental tip: Compost it! Compost helps improve soil so it holds more water and plants grow better. Allow grass clippings to stay on the lawn, instead of bagging them. The cut grass will decompose and return to the soil naturally. Food scraps and kitchen waste also make good compost, and you save money on fertilizers or other additives. Yard trimmings and food residuals together constitute 27 percent of the US municipal solid waste stream. Compost is organic material that can be used as a soil amendment or as a medium to grow plants. Mature compost is a stable material with a content called humus that is dark brown or black and has a soil-like, earthy smell. It is created by: combining organic wastes (e.g., yard trimmings, food wastes, manures) in proper ratios into piles, rows, or vessels; adding bulking agents (e.g., wood chips) as necessary to accelerate the breakdown of organic materials; and allowing the finished material to fully stabilize and mature through a curing process. Natural composting, or biological decomposition, began with the first plants on earth and has been going on ever since. As vegetation falls to the ground, it slowly decays, providing minerals and nutrients needed for plants, animals, and microorganisms. Mature compost, however, includes the production of high temperatures to destroy pathogens and weed seeds that natural decomposition does not destroy.
Did You Know That Compost Can...- Reduce or eliminate the need for chemical fertilizers.
- Promote higher yields of agricultural crops.
- Facilitate reforestation, wetlands restoration, and habitat revitalization efforts by amending contaminated, compacted, and marginal soils.
- Cost-effectively remediate soils contaminated by hazardous waste.
- Remove solids, oil, grease, and heavy metals from stormwater runoff.
- Capture and destroy 99.6 percent of industrial volatile organic chemicals (VOCs) in contaminated air.
That’s a lot of waste to send to landfills when it could become useful and environmentally beneficial compost instead! Composting offers the obvious benefits of resource efficiency and creating a useful product from organic waste that would otherwise have been landfilled. On this website, you will learn about the following. One of the most important steps for evaluating composting options is to become familiar with how the composting process works. Before you begin composting or start a composting program, you should understand the five primary variables that must be “controlled” during composting. These include the following:
- Feedstock and nutrient balance. Controlled decomposition requires a proper balance of “green” organic materials (e.g., grass clippings, food scraps, manure), which contain large amounts of nitrogen, and “brown” organic materials (e.g., dry leaves, wood chips, branches), which contain large amounts of carbon but little nitrogen. Obtaining the right nutrient mix requires experimentation and patience and is part of the art and science of composting.
- Particle size. Grinding, chipping, and shredding materials increases the surface area on which the microorganism can feed. Smaller particles also produce a more homogeneous compost mixture and improve pile insulation to help maintain optimum temperatures (see below). If the particles are too small, however, they might prevent air from flowing freely through the pile.
- Moisture content. Microorganisms living in a compost pile need an adequate amount of moisture to survive. Water is the key element that helps transports substances within the compost pile and makes the nutrients in organic material accessible to the microbes. Organic material contains some moisture in varying amounts, but moisture also might come in the form of rainfall or intentional watering.
- Oxygen flow. Turning the pile, placing the pile on a series of pipes, or including bulking agents such as wood chips and shredded newspaper all help aerate the pile. Aerating the pile allows decomposition to occur at a faster rate than anaerobic conditions. Care must be taken, however, not to provide too much oxygen, which can dry out the pile and impede the composting process.
- Temperature. Microorganisms require a certain temperature range for optimal activity. Certain temperatures promote rapid composting and destroy pathogens and weed seeds. Microbial activity can raise the temperature of the pile’s core to at least 140° F. If the temperature does not increase, anaerobic conditions (i.e., rotting) occur. Controlling the previous four factors can bring about the proper temperature.
Methods of Composting
Composting takes on many forms, from simple and inexpensive backyard or onsite composting methods to more expensive and high-tech methods such as in-vessel composting. Composting varies as much in its complexity as in the range of organic materials recovered. The most common composting methods are listed in order of increasing costs and levels of technology required and are described in greater detail on the following pages. After reviewing the science of composting above, select an appropriate method or combination of methods that will best meet your needs. Will backyard composting suffice for reducing residential volume, or should you invest in equipment and labor for larger volumes from restaurants or other businesses? Selecting the right composting equipment at an affordable price also requires careful research. Hundreds of vendors sell composting equipment and there are many variations on each type of equipment.
Man Holding Handful of Compost – Photo Courtesy of Jepson Prairie Organics
Composting Challenges
Challenges for the composting industry as a whole include a lack of consistent product quality, market research and planning, investment, accepted national compost specifications, and sophisticated product marketing. In addition, compost end uses range from city and county landscaping to niche markets such as soil remediation. Government agencies could play a larger role by increasing purchases and promotion of compost products. New technologies allow compost companies to tailor their products to specific end-uses, increasing the market value of the material. In fact, more and more compost producers are engineering multiple compost products for applications as diverse as bioremediation of contaminated soil and erosion control at construction sites. Many composting companies are packaging and marketing compost in home repair, garden center, and other retail outlets. Some companies use compost to control odors through new process technologies such as biofilters, while still others are using compost as a filter in water treatment systems.
Organic Materials
Digging in a Compost Pile with a Shovel
Yard trimmings and food residuals together constitute 27 percent of the US waste stream, as documented by EPA. An estimated 57.5 percent of yard trimmings were recovered for composting or grasscycled in 2010, a dramatic increase from the 12 percent recovery rate in 1990. Accompanying this surge in yard waste recovery is a composting industry that has grown from less than 1,000 facilities in 1988 to over 2280 in 2010 (October 2010 Biocycle State of Garbage report). Once dominated by public sector operations, the composting industry is increasingly entrepreneurial and private-sector driven, led by firms that add value to compost products through processing and marketing. Bulk retail yard waste compost sells for between $15.00 and $32.00 per cubic yard in the United States (August 2011 Compost News). While yard trimmings recovery typically involves leaf compost and mulch, yard trimmings can also be combined with other organic waste, such as food residuals, animal manure, and biosolids to produce a variety of products with slightly different chemical and physical characteristics. In contrast to yard trimmings recovery, only 2.8 percent of food waste was composted in 2010. The cost-prohibitive nature of residential food waste separation and collection is the primary deterant to expanding food waste recovery efforts. Yet in many communities, edible food residuals are donated to the needy, while inedible food residuals are blended into compost or reprocessed into animal feed. In some areas, composting operations are working with high-volume commercial and institutional food producers to recover their food byproducts, saving these firms significant disposal costs. For more information on organic materials, please visit our http://www.jgpress.com/
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