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Composting: good for trash, good for garden

Cornell University has created a model that converts campus-generated organic waste into rich compost. Cornell Farm Services owns and manages the in-house compost facility, which annually turns 1.5 million pounds of food waste and 6.5 million pounds of organic wastes from greenhouses and animal facilities into high-quality compost for use on campus and in the community, substantially reducing the University’s carbon footprint. The facility is commonly used as a living classroom, providing hands-on experiences to students with interest in agriculture, soil sciences, waste management, and sustainability. It won a 2009 Environmental Quality Award from the U.S. EPA. (Provided photo — Cornell CALS)

America’s municipal solid waste by the numbers

According to the U.S. Environmental Protection Agency, the amount of municipal solid waste generated in this country in 2017 (the most recent information available) was 267.8 million tons. That’s the equivalent of just over 4.5 pounds of waste per person per day. Paper and paperboard products made up the largest percentage of total MSW-generated materials; 25% or 67-million tons. Food waste made up the second-largest percentage; 15.2-percent or 40.7-million tons. At 35.2-million tons, or 13.1-percent of total generation, yard waste (grass, leaves, tree and brush trimmings) was the fourth largest material category (just behind plastic at 13.2%). Wood accounted for 6.7% or 17.94 million tons.

About 139.6 million tons (roughly 52%) of America’s MSW ended up in landfills. The largest component of landfilled waste; just under 22% or approximately 30.7 million tons; was food. Paper and paperboard made up just over 13%, while wood accounted for 8.7% and yard waste, 6.2%.

How to handle all of the waste being generated is an increasingly growing problem. Even if America’s cities weren’t running out of valuable, irreplaceable land — which they are — landfills would still be far from an ideal disposal solution. Landfills are large and expensive to build and operate, and there is little decomposition of trash in most landfills, especially once they’re capped. What’s more, they emit air and water pollutants. According to EPA, landfills are the third-largest source of human-related methane emissions in the United States, accounting for approximately 15.1% of such emissions in 2018.

Methane is a greenhouse gas that is more potent than carbon dioxide and contributes to global warming.

The good news is that methane can be captured and used to generate power. And although it’s not a renewable resource, landfill gas in solid waste management systems could potentially supply a very small percentage of the nation’s energy. The city of Vancouver, British Columbia, Canada, operates a landfill in the district municipality of Delta, on the US-Canada border, which uses landfill gas to provide both electricity and heat. The electricity is sold to BC Hydro and the heat is used to warm greenhouses that grow vegetables year round. By and large, however, methane emissions from landfills represent a lost opportunity to capture and use a potential energy resource.

Unnecessary waste

For the most part, disposal of food waste and yard trimmings in landfills is unnecessary. By composting, we can, individually, dramatically reduce the amount of food and yard waste that we generate, keeping it out of the solid waste stream and thereby saving landfill space and reducing methane production in landfills. And we can save ourselves some money by avoiding disposal fees.

In fact, starting July 1, a new law (Act 148) comes into effect in Vermont, making it illegal to throw away food scraps in trash. This doesn’t mean Vermonters have to compost food scraps themselves. They will, however, need to either bring their food scraps to a transfer station or dropoff, or have a hauler bring them to a composter or anaerobic digester.

The composting process

Compost is decayed organic matter that can be used to improve soil structure, add nutrients, and promote healthy soil microorganisms. Composting is one of the easiest and cheapest ways to provide healthy, nutrient-rich organic matter for your garden soil. Very little time or equipment is required. Before you start composting, however, you need to at least become familiar with the composting process and how it works.

The easiest way to compost is to just pile yard trimmings and food waste on the ground or in a bin and wait. This is referred to as slow- or cold-composting and it works well if you produce a minimal amount of waste, don’t have time to tend to your compost pile, or don’t need the compost until … say … 2022.

Hot-composting is a bit more complicated. But with the right ingredients and a little effort, you can turn a good size pile of household, workplace, or agricultural waste into compost in just a few weeks, weather permitting; often from early spring on into the fall. For the best results, a pile at least 3 x 3 x 3 feet is necessary.

Decomposing organisms need four key elements to thrive: nitrogen, carbon, moisture, and oxygen. Green organic materials (grass clippings, food scraps, livestock manure), contain large amounts of nitrogen. Brown organic materials (dry leaves, wood chips, twigs and woody debris) contain large amounts of carbon. You need to find a suitable balance of these materials, usually about a one to one ratio, to properly manage rapid decomposition.

Turning the pile regularly, every few days; moving materials from the center to the outside and vice versa, provides oxygen. You can add bulking agents, such as wood chips and shredded newspaper also, to help with aeration. Too much oxygen, however, can cause the pile to dry out, inhibiting the decomposition process.

Microorganisms need adequate moisture to survive. Organic materials contain some moisture, but additional moisture is often necessary and can be provided by exposing the pile to rain or by watering. Keep in mind that you want your pile to be moist; not soggy.

Obtaining a proper balance of materials, moisture, and oxygen takes practice, time, and patience. A little experimentation will be necessary and is part of the science of composting. When everything is working as it should, the pile’s core will remain heated to somewhere between 110 degrees F and 160 degrees F, supporting microbial activity and promoting quick, effective breakdown, as well as eradication of weed seeds and pathogens.

Some organic materials are just not appropriate for composting. Avoid putting meat scraps, bones, dairy products, pet feces, grease, fatty foods, or diseased plant material into your compost pile. Use of these materials may slow the composting process down, result in unpleasant odors and/or attract unwelcome animals or insect pests.

Avoid putting meat scraps, bones, dairy products, pet feces, grease, fatty foods, or diseased plant material into your compost pile.

Ash from your wood stove, fireplace or campfire pit should be used sparingly in gardens and never added to compost.

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