Tara Mitchell: Company sees the value of waste

Via ecoRInews John Engwer, owner of Groundscapes Express Inc., and Butch Goodwin, operations manager, recently led Ecological Landscaping Alliance (ELA) participants on a tour of the company’s composting facility, explaining how compost is made and discussing its many benefits and uses.

Through knowledge, training and, most importantly, years of experience, Engwer and Goodwin have developed a fine-tuned operation for turning waste into a valuable product.

Many people are familiar with the benefits of compost as an amendment to improve soil quality and to provide the slow release of nutrients for plants. However, compost has many other less-recognized uses and benefits in the landscape.

Compost, for instance, has a large water holding capacity. When applied over bare soil as a compost-mulch mix, it has the ability to capture and hold rainwater, preventing runoff and protecting soil from erosion. For example, a 2-inch layer of a compost and wood-chip mix, can hold about 160 gallons of water per 1,000 square feet.

Compost also has a high number of microorganisms that play an essential role in making nutrients available to plants and in breaking down and binding pollutants and heavy metals. All of these benefits make compost invaluable not only for gardens but also for protecting water quality.

Composting and the use of composed material essentially imitates the natural process of growth, death, decomposition and renewal. Composting, whether as a backyard operation or a larger-scale business, is basically a mechanism of accelerating decomposition using manual or mechanical methods.

Applying a compost-mulch mix over bare soil instantly provides the soil protection that ground cover and leaf litter naturally provide. Compost as a soil amendment speeds up landscape restoration by providing an immediate source of organic matter, moisture and microbial activity that would otherwise take years to evolve through the natural cycles of growth and decay.

Groundscapes Express’s compost begins with organic waste product brought in by local suppliers. Piles of wood chips, leaves, manure and cranberry waste line the edges of the composting area. Turning those materials into a high-quality product requires getting the proper carbon-to-nitrogen ratio and maintaining the right moisture levels.

Putting food scrap to work
With the recent implementation of the Massachusetts ban on food waste being buried or incinerated, food scrap from hospitals, restaurants and supermarkets have become another ingredient in the composting process. Food scrap from a local hospital is now incorporated into Groundscapes’ composting process.

Food scrap has the benefit of higher moisture and nitrogen, but requires additional quantities of the drier feedstocks to get the proper carbon-to-nitrogen mix and the right balance of moisture. Food scrap also adds the problem of attracting wildlife, and is more likely to be delivered with plastic debris that must be removed.

Once the right proportions of the feedstock are mixed by a loader, the material is laid out in long rows, to await the work of bacteria, fungi and other living organisms to turn the material into compost. Maintaining the right balance of water and oxygen as the material decomposes is critical to creating a high-end product. Too little water or oxygen can slow decomposition. If the material is too wet, it results in anaerobic conditions, and the living organisms necessary for aerobic decomposition die.

Piling the rows too high can also result in anaerobic conditions, because the high moisture content of organic matter makes it heavy and susceptible to compaction within the pile. An easy way to identify poor-quality compost or anaerobic compost is by smell. Bad smelling compost, or compost that smells like ammonia, is likely anaerobic and shouldn’t be used.

During decomposition,  air circulation is important not only to provide oxygen to the microbes but also to help maintain proper temperatures. As the bacteria and other organism feed on the carbon, energy (heat) is released.

Temperatures inside a pile can reach 200 degrees. However, for quality compost, the temperature must be maintained at an average of 140 degrees, according to Goodwin. High temperatures are necessary to kill pathogenic bacteria and organisms and to ensure that weed seeds are no longer viable. If temperatures are too high or too low, certain necessary bacteria and microorganisms will die, altering the process and resulting in a final product that has less microbial benefit.

Goodwin and his crew take the temperature of the compost twice a week, monitor both the interior and the exterior temperature of the piles to determine when they are ready to be turned. To turn the piles, Groundscapes uses a compost turner, which both aerates the compost and physically breaks down the material, speeding up decomposition. They also sift out large chunks of wood, rocks and other debris.

To ensure that material at the bottom of the pile gets aerated, the entire row is moved and shifted. From start to finish, the piles shrink by some 40 percent as material is broken down and moisture released. As existing piles shrink and more space opens up, new piles are added.

The finished compost feels light and smells earthy. Consistency is an essential part of the process and begins with having regular suppliers with consistent feedstock. Materials can vary, depending on the source and how much undesirable debris comes with the product. Leaf matter can vary depending on the season, and various materials have differing amounts of moisture.

Maintaining the routine of monitoring and turning also is important. Like making bread, which is also dependent on the work of living organisms, producing quality compost is based on using the right proportions of ingredients, proper handling of material, and paying attention to temperature and timing.

Goodwin said the material takes about four months to decompose and is then left to cure for another two months. It’s then screened. The finished product, dark brown, moist, light and crumbly, smelling of earth and full of microbes, is then ready to be delivered.

Compost filter tubes In addition to using and supplying compost for application to soils, Engwer created compost filter tubes for use as erosion control. Using a compost blower truck, a mix of two parts wood mulch and one part compost is blown into burlap tubes on site. Due to the weight of the compost mix — about 30 pounds a cubic foot dry and 90 pounds wet — the tubes, unlike hay bales and silt fence, don’t need to be trenched, avoiding a disturbance that leaves the soil and the site susceptible to weed seeds. The tubes also can be easily placed on compacted or frozen soils.

These burlap tubes filled with compost and wood-chip mulch provide multiple benefits for stormwater management. They physically filter sediment and serve as a physical barrier, slowing the velocity of water. The compost filters also captures and holds water, reducing flow.

The microorganisms provide additional long-term benefit by chemically breaking down, binding and reducing nutrients and pollutants, such as heavy metals, petroleum products and harmful bacteria, thus protecting water quality. And, because the burlap is biodegradable, the tubes don’t have to be removed and continue to provide a benefit as they decompose in place.

One big rain garden As the tour ended, Engwer noted that, “All the earth is a rain garden.” The entire landscape works as a system, absorbing, infiltrating, releasing, cleaning and cycling water. Like the composting process, that system is dependent on a continual supply of organic matter.

Engwer emphasized the importance of using, reusing and retaining existing wood, stumps, brush and other natural material on site so that organic matter can remain part of the cycle of growth, death, decomposition and renewal.

Tara Mitchell is a landscape architect with the Massachusetts Department of Transportation. Her responsibilities include design, design review and construction services for landscape restoration. This story originally ran in an Ecological Landscaping Association newsletter.