Biochar vs. Compost: What Is the Difference?

Biochar and compost bring different strengths to garden soil. Compost supplies decomposed organic matter and nutrients. Biochar adds a porous, carbon-rich material that lasts for years in soil and can help retain water and nutrients. Together, they connect a source of plant nutrition with a lasting soil amendment. ¹, ²

What each amendment brings to soil

Compost is made through biological decomposition. With oxygen and moisture, microorganisms break down leaves, food scraps and other organic materials. After the active composting stage, the material matures into finished compost. Added to soil, it supplies nutrients and improves structure, aeration and moisture storage. ¹

Biochar is made by heating biomass, such as wood, with limited oxygen. This creates a stable carbon structure. In soil, biochar can help retain water and nutrients and support microbial activity. Its resistance to decomposition makes it a lasting addition to the soil around plant roots. ²

These roles complement each other. Adding biochar to a compost routine can help keep moisture and nutrients available in the soil where plant roots can use them.

Biochar and compost compared

Both materials can improve soil structure and moisture retention. Their differences explain why they make useful partners. ¹, ²

How compost helps charge biochar

Biochar’s pores and surfaces can hold water and nutrients. Mixing it with moist compost brings those surfaces into contact with a nutrient source before the blend goes into soil. Gardeners often call this preparation “charging.” Compost supplies the nutrients; biochar provides places where they can collect and be retained. ³, ⁴

There are two ways to bring the materials together. Mixing biochar with finished compost is convenient when you already have mature compost on hand. Co-composting means adding biochar while the compost is being made, so it interacts with the organic materials throughout decomposition and curing.

Co-composting research helps explain how this partnership develops. Researchers found that nutrient-rich organic matter formed thin coatings on biochar, including inside its pores. These coatings strengthened its interaction with water and increased nutrient retention, adding to the useful properties of the biochar itself. ³

Those retained nutrients support plants. In a greenhouse trial with quinoa in a poor sandy soil, co-composted wood biochar improved plant growth. Plants receiving it grew more than those given untreated biochar or no biochar, with the same fertilizer and compost additions. The researchers linked the benefit to nutrients captured during composting, including nitrogen that remained available to plants. ⁴

Bringing the partnership into your garden

For a home blend, mix biochar evenly with finished compost and moisten it so the materials make good contact. Incorporate the blend into the soil where roots will grow, following your biochar product’s application directions. Our guide to preparing biochar before soil use explains mixing, moisture and optional preparation time.

Premium Biochar provides the biochar ingredient for your own blend. For a prepared option, Biochar Pro Garden Mix™ combines biochar, compost and mycorrhizae in a product designed to mix into existing soil. Follow the directions for the product you choose; straight biochar and a compost-containing blend have different application rates.

For more on how biochar supports plant nutrition, read about its role in holding and supplying nutrients to roots. You can also explore Wakefield’s gardening solutions to find a biochar product for your planting plans.