One often-overlooked benefits of organic lawn care, especially compost top dressing is carbon sequestration. A lawn can help combat climate change, and compost is the secret weapon.
Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide (CO2) in plants, soil, and other natural reservoirs. Healthy soil acts as a powerful carbon sink, pulling CO2 from the atmosphere and locking it away underground. This helps reduce greenhouse gases, mitigating the effects of climate change.
Lawns, when managed properly, can play a significant role in carbon sequestration. While lawns are often criticized for their environmental impact due to high water use and chemical inputs, an organic and sustainable approach can turn them into effective carbon sinks.
How Lawns Contribute to Carbon Sequestration
1. Grass Growth Captures Atmospheric Carbon
Grass, like all plants, captures carbon dioxide during photosynthesis and converts it into organic compounds used for growth. This carbon is stored in both the plant material above ground in the blades of grass, but it is also transferred below ground to be stored longer in the root system and soil.
Lawns are perennial, so they are active every year capturing carbon. In many southern climates, they grow year-round. Since some carbon is stored in the blade, regular mowing encourages new growth, which further captures more CO₂. Utilizing mulch mowing techniques, like done by Clean Air Lawn Care, returns the plant material to the soil to break down and trap even more carbon.
2. Soil as a Long-Term Carbon Storage
The real magic of carbon sequestration happens below the surface. Lawns contribute to soil carbon storage in several ways:
- Root Exudates: Grass roots release organic compounds into the soil, feeding microbes and fostering carbon-rich organic matter.
- Root Turnover: As roots grow and die, they leave organic material in the soil, which is broken down into stable forms of carbon.
- Microbial Activity: Healthy soil microbes convert organic matter into humus, a long-lasting carbon reservoir.
Well-maintained lawns with deep root systems store more carbon, especially when practices like overseeding and compost top dressing are used.
3. Reduction of Soil Erosion
Dense, healthy grass covers the soil, preventing erosion and keeping stored carbon in place. Without erosion, the carbon stored in the soil isn’t lost to the atmosphere.
By reducing the risk of erosion, lawns help maintain the integrity of their carbon storage over time.
4. Lawn Clippings Act as Organic Matter
Leaving grass clippings on the lawn after mowing by mulching mowing instead of bagging provides additional carbon input to the soil. The clippings decompose and:
- Enrich the soil with organic matter.
- Feed soil microbes that enhance carbon sequestration.
- Reduce the need for synthetic fertilizers, which can emit greenhouse gases during production. Some estimates have grass clippings returning up to 40% of it’s nitrogen to the soil, further reducing the amount of input needed.
Grass clippings are an easy way to enhance carbon capture and soil health.
5. Organic Lawn Care Enhances Carbon Sequestration
Switching to organic practices amplifies a lawn’s ability to sequester carbon. These practices include:
- Adds organic matter to the soil, improving its structure and increasing its capacity to store carbon.
Avoiding Synthetic Fertilizers
- Prevents disruption of soil microbial communities, which are essential for converting organic matter into stable carbon forms.
Aeration
- Increases oxygen flow to the soil, stimulating microbial activity and boosting carbon sequestration.
Water Conservation
- Deep, infrequent watering encourages root growth, which directly increases below-ground carbon storage.
Using Native or Drought-Resistant Grasses
- These grass types require less maintenance and develop deeper root systems, enhancing soil carbon storage.
6. Supporting Biodiversity
A well-maintained organic lawn fosters a diverse ecosystem of plants, microbes, insects and animals. This biodiversity enhances soil health and stabilizes the carbon stored in it. Biodiversity in the lawn ecosystem supports more robust carbon storage and overall soil resilience.
7. Balancing Inputs and Outputs
Traditional lawns with high chemical and water inputs may offset some of their carbon sequestration benefits due to emissions associated with mowing, fertilizing and irrigation. However, lawns managed with low-impact, organic methods can shift the balance toward being net carbon sinks. The pillars of the Clean Air Lawn Care approach — battery-powered mulch mowing, organic fertilizers, promotion of smart irrigation controllers, etc. – enables the carbon sequestration to be robust and effective.
How to Maximize Your Lawn’s Carbon Sequestration Potential
- Switch to Organic Practices
- Use compost, avoid synthetic fertilizers, and implement natural weed control methods like corn gluten or iron-based herbicides.
- Mow High and Grasscycle
- Mow grass to a height of 3-4 inches for cool season grasses and 2.5 inches for warm season turf to encourage deeper roots and leave clippings on the lawn to decompose.
- Aerate Annually
- Loosen compacted soil to promote root growth and microbial activity.
- Add Organic Matter
- Apply compost to boost soil carbon and improve fertility.
- Overseed with Deep-Rooted Grass Varieties
- Use drought-tolerant or native grasses to enhance root depth and increase soil carbon storage.
- Water Deeply and Infrequently
- Encourage deeper roots by watering less frequently but thoroughly.
- Convert Marginal Areas to Native Plantings
- Replace rarely used lawn sections with native plants or pollinator gardens, which store even more carbon and require less maintenance. While not part of the lawn itself, trees and shrubs contribute to carbon storage in their biomass and improve soil health at their roots. Plant trees or shrubs along the edges of your lawn to enhance biodiversity and provide natural shade.
- Practicing Organic Weed Control
- Organic weed control avoids the use of herbicides that can damage soil health and inhibit microbial activity, both of which are crucial for carbon sequestration. Use natural methods like hand-pulling weeds, applying corn gluten meal as a pre-emergent, or promoting dense grass growth to crowd out weeds.
- Using Mycorrhizal Fungi
- Mycorrhizal fungi form symbiotic relationships with plant roots, extending their reach and improving carbon storage in the soil. These fungi also enhance nutrient uptake and soil structure. Mycorrhizae is a component of the Clean Air Lawn Care soil builder, a liquid application used in conjunction with organic fertilizer applications to bolster root and soil health and vitality. It’s especially beneficial as an application when overseeding or feeding new turf.
- Encouraging Earthworm Activity
- Earthworms aerate the soil naturally and help incorporate organic matter, increasing the soil’s carbon storage capacity. Their castings are also a building block in healthy soil structures. Avoiding heavy pesticide usage will prevent damaging earthworms, and maintaining organic matter in the lawn through compost top dressing and leaving grass clippings will attract more worms.
- Rotating Organic Amendments
- Adding organic amendments like biochar, leaf mold or composted manure also enriches the soil and increases the carbon content. It provides varying food sources for the microbes in the soil, and improves the ability for the soil to hold water and nutrients.
Lawns as a Climate Solution
When managed responsibly, lawns can act as significant carbon sinks, helping to offset greenhouse gas emissions. While forests and wetlands are often touted as the gold standard for carbon sequestration, lawns offer an opportunity for homeowners to make a tangible, positive impact at the local level.
Benefits of Carbon-Sequestering Lawns
- Cleaner air and water.
- Reduced urban heat island effects.
- Improved soil health and fertility.
- Aesthetic and recreational value.
And the biggest piece of the sequestration puzzle is the compost top dressing. By actively adding carbon to the lawn in decomposing plant matter, which will continue to break down and nourish the soil, the volume of carbon accelerates much quicker than just leaving lawn clippings on the lawn.
Compost is packed with organic matter, which is essentially carbon that has been captured by plants and microorganisms. Applying compost to the lawn is not just feeding the grass—it is enriching the soil with carbon. Here’s how it works:
- Organic Matter Incorporation: The organic matter in compost is broken down by soil microbes, releasing nutrients for your grass while also increasing the soil’s carbon content.
- Boosting Microbial Activity: Compost fuels microbial life in the soil, creating a thriving ecosystem of bacteria and fungi. These microorganisms help convert atmospheric CO2 into stable forms of organic carbon that can be stored in the soil for decades.
- Encouraging Root Growth: Healthy soil promotes deeper root systems, which pull more CO2 from the air and store it underground. Grass roots, in turn, feed soil microbes, creating a virtuous cycle of carbon capture.