Biochar Field Guide by MKSK

Biochar

An MKSK field guide for communities and developers with goals to improve resilience and combat climate change by sequestering carbon out of the atmosphere.

LAB FOR CLIMATE & BIODIVERSITY RESILIENCE

Where can Biochar

What is Biochar?

Biochar is toasted organic matter that is used as a soil additive. Made from organic waste products, like tree branches or corn cobs. Biochar is extremely durable in the soil, performing its function without weathering or decaying for thousands of years. This makes biochar a powerful means of sequestering carbon.

Typically, organic matter in living tissue follows a cycle of pulling water and nutrients from the ground and CO2 from the air to make the carbohydrates in plant tissues. When living things die, these carbohydrates break down and release the water and CO2 into the air and the nutrients back into the soil. Making biochar breaks the cycle by locking up the carbon from organic matter and turning it into a nutrient magnet. In other words, biochar taps carbon from the life cycle and sequesters it into the soil where it helps more organisms to grow, thrive, and sequester still more carbon.

How is Biochar made?

Making biochar is like blackening bread in a sealed toaster. Heat is applied to an organic material. By cutting off the supply of air, the toasting process is starved of oxygen, allowing the heat to be increased without igniting the material. This turns organic compounds into gases that further feed the process, leaving carbon behind.

Using just the right level of heat, matched to the organic material being charred, leaves nearly pure carbon. This process is called pyrolysis. Because a large majority of the fuel for creating biochar comes from organic compounds released from the organic material, biochar production has a small carbon footprint.

How does Biochar work?

Biochar works because it is nearly pure carbon. The carbon is negatively charged, and so it attracts most nutrients, which are positively charged. Looking through a powerful microscope reveals that the surface of a biochar particle is fantastically complex, full of ridges, craters, and canyons. These are the skeletal carbon remains of the organic matter’s cells. This complexity provides enormous surface area per volume of biochar, lots of room for nutrients and water to perch.

Biochar is most commonly mixed into planting soil for lawns (to a 3” to 6” depth) and planting beds (to a 6” to 18” depth). Because it is a nutrient bank, biochar evens out wet/dry and hot/cold conditions and creates more uniform and lower stress conditions for planting.

Mix biochar into soil at a rate of 3% to 5% of pure biochar per unit of soil, depending on the sand and clay composition of the soil. For a typical lawn, biochar sequesters about 5 tons carbon/acre, or about 18 tons of carbon dioxide/acre. In beds, at a depth of 12” to 18”, biochar sequesters about 15 to 22 tons carbon/acre, about 55 to 80 tons of carbon dioxide/acre.

CO Sequestration 2

Benefits of Biochar in urban environments:

Soil Amendment: Urban soils often suffer from compaction, contamination, and poor structure due to human activities. Biochar can improve soil fertility, structure, and water retention, enhancing urban green spaces such as parks, gardens, and urban farms.

Stormwater Management: Urban areas face challenges with stormwater runoff, which can lead to flooding and pollution of water bodies. Biochar can be integrated into green infrastructure designs such as rain gardens, bioswales, and permeable pavements to improve water infiltration and filter pollutants from runoff.

Carbon Sequestration: Biochar production can sequester carbon and mitigate greenhouse gas emissions, contributing to air quality improvement in urban areas. Additionally, biochar can be used in biofiltration systems to capture particulate matter and pollutants from the air.

Waste Management: Urban centers generate significant amounts of organic waste, which can be converted into biochar through pyrolysis. This process not only reduces waste but also produces a valuable soil amendment that can be utilized locally.

Urban Agriculture: Rooftop gardens, community gardens, and urban farms can benefit from biochar’s ability to improve soil fertility and water retention. Incorporating biochar into urban farming practices can enhance food production while sequestering carbon and reducing greenhouse gas emissions.

Green Infrastructure: Biochar can be incorporated into green roofs and urban tree pits to improve soil quality and plant health. This helps mitigate the urban heat island effect and enhances biodiversity in cities.

Remediation of Contaminated Sites:

Biochar’s adsorption properties make it effective for remediation of contaminated soils in urban brownfields or industrial sites. It can immobilize heavy metals and organic pollutants, reducing their mobility and toxicity.

Community Engagement and Education:

Incorporating biochar projects into urban sustainability initiatives can engage communities in environmental stewardship and provide educational opportunities about soil health, carbon sequestration, and sustainable land management practices.

Biochar offers multifaceted benefits for urbanized areas, addressing challenges related to soil degradation, water management, air quality, waste reduction, and community resilience. Its versatility makes it a valuable tool for promoting sustainability and resilience in urban environments.

LAB FOR CLIMATE & BIODIVERSITY RESILIENCE