There is less than 5% of residential food waste that is currently being composted around the world. To be exact, about 3.7% as of an April 2023 report. However, in contrast to the 1.3 billion tons of food wasted each year, this percentage doesn’t even scratch the surface. This food waste ends up in landfills, waiting to be decomposed to release methane, a potent greenhouse gas. So, what can we do in order to prevent this from happening?
Composting is widely known for its beneficial effects for recycling organic waste materials to create valuable soil amendment. Scientifically, it is the transformation of raw organic materials into biologically stable, humic substances suitable for a variety of soils and planet uses (Leslie, 2000). But if it’s so good, why aren’t more people composting their food waste? This could be due to a variety of reasons from perceived inconvenience, odor, and limited infrastructure, but most importantly, less and less people know of its actual environmental benefits. In this article, we examine the importance of composting and the science behind it.
The process of composting involves the breakdown of a molecular structure into its elemental components–into simpler compounds or even atoms (Insam & de Bertoldi, 2007). There are two main phases in the process of composting: decomposition and stabilization. The final product is compost which is made up of carbon dioxide, water, minerals, and stabilized organic matter, which is essentially used as plant fertilizer to enrich the oils and support plant growth (Insam & de Bertoldi, 2007) Decomposition requires its very first step, the exothermic process, where it takes the waste and turns it into the form of heat simply by increasing the temperature in the mass (Insam & de Bertoldi, 2007). As temperature increases, thermophiles take over, continuing to the thermophilic phase. This stage becomes known as the active phase of composting, where degradable compounds and oxygen are consumed, pathogens and weed seeds are killed, and phytotoxins are eliminated (Leslie, 2000). Then we proceed to the two mesophilic phases. In these stages mesophilic organisms recolonize the whole waste pile and the curing phase begins (Leslie, 2000). Curing allows organic materials to continue to decompose, which are then converted to biologically stable humic substances. It is common practice in commercial composting to cure for 1 to 4 months, and for homeowner compost piles to cure for as long as 6 to 9 months (Leslie, 2000). Finally, the stabilization phase occurs after the temporary release of phytotoxins, where phytotoxicity is completely overcome and the final product is beneficial to plant growth (Insam & de Bertoldi, 2007).
Now you know how composting works, so what should you compost? You should compost greens–think nitrogen-rich materials like vegetable scraps, coffee grounds, and fresh grass clippings. These green materials have a lower supply of carbon relative to nitrogen (C:N), which means it has a faster composting process (Insam & de Bertoldi, 2007). For non-food waste, brown materials that are carbon-rich like dried leaves, cardboard, and straw. And if you’re worried about creating odor or attracting pests, avoid composting meat, dairy, oily foods, or pet waste. Wastes like these are more nitrogen rich, so it lowers the C:N ratio to less than 20:1, causing nitrogen to be lost to the atmosphere leading to foul odor (Insam & de Bertoldi, 2007). Lastly, make sure to keep it moist to speed up the decomposition process. Low moisture content impedes the composting process because it leaves your compost pile more susceptible to spontaneous combustion due to temperature (Insam & de Bertoldi, 2007). With patience and consistent practice, you’ll transform waste into nutrient-rich compost for your garden!
Sources Cited
Leslie, R. C. (2000) Composting: Art and Science of Organic Waste Conversion to a Valuable Soil Resource. Laboratory Medicine, 31(5), 283-290. https://doi.org/10.1309/W286-LQF1-R2M2-1WNT.
Insam, H., de Bertoldi, M. (2007) Chapter 3 Microbiology of the composting process. Waste Management Series, 25-48. https://doi.org/10.1016/S1478-7482(07)80006-6.
