Cover Cropping as a Climate Solution

Posted on Tuesday, 14 December 2021 under Supporting Farmers and Ranchers Feature

Building soil health is a key climate mitigation tool. Farmers from all sectors require healthy soil for a healthy farm. Strategies to build soil health include reduced tillage, intercropping, on-farm nutrient cycling, and cover cropping. Cover cropping is a popular method for farmers across BC, providing benefits for agricultural producers and our climate.

Cover cropping is the practice of growing plants to help protect and improve the soil. Kevin Elmy from Cover Crops Canada has spent decades researching cover crop varieties. Continuing his research and working as a cover crops consultant for Imperial Seed, Elmy emphasizes that cover crops build healthy soil but can also have an economic benefit for farmers. Farmers can underseed a crop that will grow below a cash crop so after the cash crop is harvested, the cover crop can be harvested or grazed. The first thing a farmer should do is set cover cropping goals. Elmy says, “Once you have your goals set, then we can go in and start developing a plan of how to manage the cover crops.”

With additional time, energy, and financial resources, cover crops can be an efficient tool for mitigating climate change and increasing soil organic matter – an outcome that is hugely beneficial for farmers.

Capturing carbon supports farmers as well as surrounding ecosystems. Click To Tweet

An essential component of soil health is the growth of mycorrhizal fungi in the root system. “Mycorrhizal fungi soils build nutrient-dense food,” according to Elmy. Developing soil health goals leads to improved crops for farmers and acts as an important climate solution.

Water infiltration, weed pressure, and erosion problems, Elmy says, “are all fixed by increasing carbon in your soil.” Carbon acts as a cleaner in soils and can help treat any contaminants. “The more carbon we have in the soil, the more that soil can clean the whole system surrounding it.”

Capturing carbon supports farmers as well as surrounding ecosystems. Keeping something green and growing as many days out of the year as possible is an important climate initiative. Elmy says, “When we have a plant that is in a vegetative stage, up to 80 percent of the carbon captured through photosynthesis goes back into the soil to feed the soil biology. As we put more carbon in the soil, we increase the porosity of it.”

Utilizing cover crops can reduce and eliminate chemical inputs by building natural fertility in the soil.

Farmers across BC are reaping the benefits of using cover crops throughout the season. Ben Corno at Heavenly Roots Farm stresses the biggest benefit of cover crops on their farm is covering the soil during the winter months. Corno says, “Having [a plant] absorbing the impact of the rain, reducing soil erosion and keeping the compost and nutrients we add in the summertime held by the cover crop is very valuable, it’s had a positive impact on our soil porosity.”

Utilizing cover crops can reduce and eliminate chemical inputs by building natural fertility in the soil. Corno says, “Cover cropping allows us to make our fertility program more meaningful. We use the cover crop to keep safe all of the beneficial inputs we are adding to the soil.” The right cover crop can absorb any additional, potentially harmful, greenhouse gas outputs. For example, using nitrogen-fixing legumes to absorb excess nitrogen in the soil at the end of the growing season reduces run-off.

Cover crops include a wide range of species, including ryegrass, clover, peas, vetch, and so many more. Planting a diverse mix of cover crops is best. Elmy explains the reason that diversity is so crucial,

“When we start looking at blends, we have annual clovers in mixes and they’re great because all of your legumes have evolved through centuries to grow with grasses. That magical link is mycorrhizae; it links those two plants together. The legume, to fix the nitrogen through the rhizobium, needs a lot of phosphates, which the grasses accumulate. The mycorrhiza can solubilize a lot of phosphate in the soil, so it can shuffle that phosphate into the legume to fix nitrogen that will shuffle to feed the grass the nitrogen. Then when you throw flax and sunflowers into it, and other mycorrhizal broadleaf plants, it does very similar things. Because we have more diversity in the root exudates, we’re going to have more diversity in the biology growing in that soil and the less amount of issues we’re going to have in the soils.”

Introducing cover crops into the farm rotation is not without challenges. Elmy explains, “It’s finding species that work within your system and the timing of planting.” With cash crops growing throughout the season, finding an opportunity to plant a cover crop is difficult. For Stefan Butler at Nutrient Dense Farm, there is a small window for planting cover crops. Butler says, “As far as production fields go, by the end of August, as soon as I crop out and am not using that bed for another crop, I cover crop it.” Another challenge is pests feasting on the cover crop mixes; in southern BC, animals like geese and deer are seeking out food sources to meet their nutritional needs. Elmy explains that farmers can reduce unwanted animal pressure by having more diverse cover crops growing throughout the year. As well, farmers can plant a lure crop, when space is available. Elmy says, “People can grow a cover crop back in the corner away from everything else. And that’s the wildlife feed.”

farmers can reduce unwanted animal pressure by having more diverse cover crops growing throughout the year. Click To Tweet

The main consideration for farmers is what to plant and how it will benefit the farm ecosystem. Elmy says, “Whether it is cover cropping or intercropping, we’re growing these plants together so we have to look at what plants naturally cooperate – what grows together?” He stresses diversity over density and advises farmers to choose a selection of two or three cover crops that will contribute positively to the diversity of their farm, obviously keeping goals in mind. For example, if a farmer wants to suppress weeds, they need to tie up nitrate and increase calcium. Planting a grass-legume mix such as annual rye and hairy vetch can achieve this goal. The two work together to tie up nitrogen and suppress weeds.

This effective farming technique is beneficial for both farmers and the climate. With additional time, energy, and financial resources, cover crops can be an efficient tool for mitigating climate change and increasing soil organic matter – an outcome that is hugely beneficial for farmers. Crops thrive in balanced, healthy ecosystems.

Farmers can start small and create goals and cover cropping plans that achieve results year to year. Eventually, as progress is made, long-term soil health goals are attainable. Elmy says, “Once we open up our minds, we figure out solutions.”