Making Biochar in the Ground to Improve Soil

Improve your soil by making biochar in the ground. DIY biochar enhances nutrient availability and also enables soil to retain nutrients longer.

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by Adobestock/Инга Мезенцева - st

Improve your soil by making biochar in the ground. DIY biochar enhances nutrient availability and also enables soil to retain nutrients longer.

Last year, I committed one of the great sins of gardening: I let weeds go to seed. Cleaning up in fall, I faced down a ton of seed-bearing foxtail, burdock and crabgrass. Sure, I could compost it hot to steam the weed seeds to death, but instead I decided to try something different. I dug a ditch, added the weeds and lots of woody prunings, and burned it, thus making biochar. It was my new way to improve soil–except the technique is at least 3,000 years old.

What’s biochar? Basically, it’s organic matter that is burned slowly, with a restricted flow of oxygen, and then the fire is stopped when the material reaches the charcoal stage. Unlike tiny tidbits of ash, coarse lumps of charcoal are full of crevices and holes, which help them serve as life rafts to soil microorganisms. The carbon compounds in charcoal form loose chemical bonds with soluble plant nutrients so they are not as readily washed away by rain and irrigation. Biochar alone added to poor soil has little benefit to plants, but when used in combination with compost and organic fertilizers, it can dramatically improve plant growth while helping retain nutrients in the soil.

illustration of a farmer stirring smoking biochar

Amazonian Dark Earths

  • Updated on Jan 23, 2023
  • Originally Published on Jul 7, 2020
Tagged with: biochar, Improve Soil, International Biochar Initiative, soil, Soil Building, Terra Preta
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