Biochar soil conditioners are hitting the retail market in a big way, and you will soon (maybe already) find these products on shelves of garden centers near you.

Product labels on biochar products tout higher yields and drought resistance for crops planted in biochar-amended soils, and many also claim that using biochar reduces global warming. Is it too good to be true? Research is still in progress, but history suggests biochar amendments may improve soil over the long-term.

Long-term improvement is a little different than the silver bullet for which many gardeners are looking, but it is long-term improvement that may be a little more permanent than the regular recommendation to add compost. If you decide to use it, remember:

• Scientists are still researching just how much to use on different kinds of soils for best benefits.

• Do it more than one time.

• Use a commercial product unless you spend a lot of time honing the process.

• Fireplace and wood stove ashes are very different from biochar and can have a negative effect on garden soils.

What is biochar? It is charcoal meant for use as a soil amendment. The new name distinguishes it from charcoal meant for use as fuel, but it is produced in the same way and looks and feels the same.

Charcoal production is an ancient practice, and roughly 2,500 years ago the native people of a certain region of the Amazon basin made charcoal and incorporated it into the soil. The land is still highly fertile, despite being surrounded by poor, nutrient-depleted soils. While correlation and causation are separate and remain unproven in this case, charcoal addition to soil is certainly showing promise.

Over the last several years, researchers have trialed biochar amendments with mostly positive results. Since biochar is organic matter, it should seemingly have the same effect as additions of compost, chopped leaves, and/or other organic materials.

In addition to providing some nutrients and improving the water-holding capacity of soil, biochar (and other organic matter) increases microbial activity and can make nutrients, water and air more available to plant roots.

Global warming improvement claims are a little more complicated, but think about it step-by-step. Plants absorb carbon dioxide from the atmosphere as they grow. Once the plant dies or is harvested, the material breaks down and carbon is released back into the atmosphere. When the plant is turned into charcoal or biochar, about half of the carbon is held in the charcoal instead of being released. Carbon in charcoal remains stable for millions of years, so it puts a halt in the process and could essentially reduce the amount of carbon dioxide in the atmosphere.

Biochar has great appeal to improve soils in regions where resources are limited and to be a product farmers can make from their own plant waste.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation. She is the host of “The Garden Show” and has been a gardener since childhood. Send your gardening questions and feedback to features@ljworld.com.