Features Agronomy Earth Week Eco-Friendly Soils Turf Revival
The important role compost plays in tackling climate change

Paying mindful attention to the soil in landscaping, gardening and agriculture is an effective means of tackling climate change in a variety of ways, including carbon sequestration, water conservation, reduced inputs and improved nutrition.

Representatives of the Compost Council of Canada shared some of the best practices for recruiting soil to tackle climate change at January’s Landscape Congress conference in Toronto.

“Soil is a four-letter word for hope,” Susan Antler, executive director of the Compost Council of Canada, said. “Soil is a fight for the best possible life on earth. For those in the industry who manage soil, this is our ally.”

Properly managed soil supports biodiversity, cleans the water, and leads to greater productivity and a healthier economy, she said, adding more attention must be focused on organics.

Organic material accounts for about 40 per cent of the waste stream. Much of it “thoughtlessly” goes into landfills and contributes to climate change.

“When you put organics in a landfill, it basically is a tomb, and it’s the organics that result in methane being produced,” Antler said, noting the gas is about 80 times more powerful than carbon dioxide and greenhouse gases.

Landfills are the No. 2 emitter of methane in Canada, “and it’s needless.”

Antler was one of the founding members of the Compost Council of Canada in 1991 at a time when garbage-laden barges traveled northward along North America’s Atlantic coast, looking for a port willing to accept the loads.

She said organics in the form of food waste, biosolids, pulp and paper, and other materials can be diverted from landfills to soils where it can be empowered.

The Compost Council of Canada is a national advocacy and infrastructure development organization which is dedicated to advancing organic recycling and the return of organic matter to the soil for ongoing health and vitality. The organization also serves as a frontline offence and defence to climate change and resiliency.

The council recently partnered with the Soil Conservation Council of Canada on a two-year study in which Canadian soil scientists explored the relationship between soil and tackling climate change.

Antler said the tendency is to look at soil from a surface perspective, but what lies underground needs to be the focus.

Compost is rich in organic matter
Glenn Munroe, manager of special projects for the Compost Council of Canada, said the organisms found in compost are the same as those found in soil, but noted compost tends to be richer in those organisms. Microbes cluster around the roots of plants.

Fungi and bacteria are found everywhere in soil, and predatory protozoa consume the nutrient-rich bacteria and “poop out” the nutrients at the roots of plants. Munroe said as plants put out sugars to their roots, they attract bacteria and fungi. Microbes consume them and release nutrients in a plant-available form in the root zone.

“This is probably the biggest factor involved in the nutrition of whatever it is that’s being grown,” he said.

Antler cited the “six Cs” of good soil management: reducing soil compaction, cultivating carefully, continuous living plant cover, using cover crops, adopting crop and plant diversity, and using compost and other soil amendments.

“These six Cs have to be incorporated as it works well for those who are embarking on soil health,” she said. 

Pushing organic matter deeper into the soil is a means to store carbon and a way to fight climate change, and can be achieved through the adoption of soil health practices and principles, incorporating them properly and continually monitoring them, she said.

A good, healthy shovelful of soil should contain between six and 10 earthworms, Antler added.

Cost-efficiency, marketing and sustainability are three good reasons for people to care about soil health, Munroe said. 

Although costlier at the outset, adoption of the six Cs becomes less expensive over time, he added. There are more upfront costs in the beginning, but after two or three years the practice becomes more cost effective.

It’s easier for a landscaping company to market itself as being “green” if it adopts the six Cs toward better soil health. The Compost Council of Canada has signage available to those who use compost on lawns. The signs provide a good marketing tool for practitioners of healthy soils.

Other marketable features of healthy soils are that they’re resilient, are drought resistant, are less prone to flooding and are non-polluting.

Achieving sustainability
Because healthy soils require fewer inputs – including water – sustainability is achieved. 

“As your soil improves, input requirements are reduced,” Munroe said, adding greater use of fertilizers and crop protection products are necessary when soil health is poor.

“Because healthy soils have a better structure, they hold more water,” he said. “They allow more water to penetrate rather than run off which is another cost saving. And, in the long run, they require less labour.”

A healthy soil is one that hosts a thriving soil food web with different creatures consuming different creatures. The greater the diversity, the healthier the soil will be, Munroe said.

He noted a Harvard University study was conducted between 2004 and 2009 during which the institution wanted to initiate an organic system for its campus grounds. The health and aesthetics of the university’s grounds had previously posed a challenge. Soil testing was conducted to see what biodiversity existed in the soil. It was decided to build the soil’s health with compost and compost tea.

Irrigation requirements were subsequently reduced by 30 to 50 per cent over the course of the study while the turf’s root systems increased in depth by three to five inches. Disease and weed pressures were noticeably reduced, and an overall cost savings was realized. 

Harvard staff were trained to make their own compost and compost tea.

Munroe said lawns sequester an average of one to 1½ tons of carbon per hectare per year.

“Grass is a wonderful carbon sequester, but it has to be managed properly,” he said.