As spring approaches, chilly nights and frozen grounds reluctantly give way to warm, sunny skies and lush regrowth of native flora.  During this time of rebirth, memories of icy, treacherous roads and back-breaking shoveling quickly fade as eager hands plunge into rich, fertile soils.

For many of us, spring evokes childhood memories of a simpler time when gardening was a mainstay of most Maine families. Increasing demands for organic foods and concerns over the lack of sustainable agricultural practices has resulted in a resurgence of home gardening.  Many first time gardeners often ask, “What is the best way to ensure that my garden will flourish?”

One way to ensure a successful gardening season is to remember to add organic matter to your soil prior to spring planting.  A healthy balance of organic matter provides a multitude of soil benefits by serving as a reservoir for nutrients and water in the soil, helping to reduce soil compaction, while simultaneously enhancing water movement through the soil.  A simple and inexpensive method of obtaining organic matter is to start your own compost pile.

Composting is a biological process in which microorganisms (actinomycetes, bacteria and fungi) convert organic materials (carbon and nitrogen compounds) into a nutrient-rich, soil-like product called humus. Overall, composting is characterized as an aerobic process because the microorganisms that do the bulk of the work require oxygen to carry out their metabolic activities. Additionally, in order for microbial activity to occur within a compost pile, there must be suitable amounts of carbon, nitrogen and moisture as well.

Microbes rely upon a balance of carbon and nitrogen (generally in a ratio around 30-40 parts carbon to 1 part nitrogen).  Carbon, like leaves, paper and sawdust, provides the energy source and nitrogen, such as food scraps, and fresh cut grass, is used as the building blocks to produce more microbes.  Additionally, the microbes prefer to live in a moist environment (around 55 percent moisture).

Finally, in order to perform well, microbes need oxygen to help fuel their metabolism.  For example, if a pile is well aerated, microbes work aerobically and the byproducts of their metabolic efforts are heat, carbon dioxide and water vapor, ultimately resulting in a reduction in both mass and volume of the original raw ingredients.  However, in the absence of oxygen (anaerobic), piles operate at a less efficient level, resulting in the production of odorous byproducts, such as volatile organic acids (VOAs).

A curing phase usually follows the active compost phase and can help to prevent odorous conditions from occurring.  During curing, the microorganisms still feed, but at a slower pace, resulting in a reduction in temperature, carbon dioxide and water vapor production.  Left undisturbed, the microorganisms will continue to feed until all of the original organic materials are consumed. The final product is a nutrient-rich, soil amendment that is odor free, biologically stable and provides needed organic matter to soils.

Providing a product that enhances soil quality is only one of the many benefits of composting.  In fact, all across the United States, municipalities have established large-scale solid waste municipal composting facilities to manage large volumes of organic materials, such as leaves, grass clippings, and food scraps, simultaneously saving disposal fees.

Here in Maine, for example, over 80 municipalities have elected to compost collected leaf and yard debris instead of sending it to landfills. The finished compost is then made available for home and garden use at little to no cost. This in turn benefits the environment by ensuring that valuable nutrients remain locally and are returned to the soils where they belong.

Composting is not just a good idea for the home gardener but also a valuable, cost-effective part of our state’s solid waste management efforts, providing a balanced approach to enhance the sustainability of natural resources.


This column was submitted by Mark King, an environmental specialist with the Maine Department of Environmental Protection’s Bureau of Remediation and Waste Management.