Charcoal-enriched soil improves maize yield

Adding biochar to farm soil can help boost maize yield, according to research. The study, which was published in the European Journal of Agronomy, showed that the addition of biochar to Belgian farm soil was linked to a considerable increase in maize/corn (Zea mays) yield. The study authors explained that historical charcoal, or biochar, can boost maize yield since it helps increase the available water content in the soil. Research findings revealed that charcoal had a greater effect on maize yield was when it was added during the driest growing season in Belgium.

Test results showed that the charcoal-enriched soils had a greater available water content compared to the controls. The scientists examined above-ground silage maize yield in farm soil beneath historical charcoal kilns or black spots with less than 150 years of enrichment. The soil was then compared to adjacent soils in southern Belgium from 2014 to 2016.

On average, data revealed that in the well-fertilized farmable soil, the average maize yield was 23 percent higher in the black spots, unlike in the adjacent soils. On the other hand, the average charcoal-C concentration was 63 percent of total soil organic carbon (SOC) in the black spots.

SOC refers to the carbon component of organic compounds. Because it can be difficult to directly measure soil organic matter, laboratories measure SOC instead.

Maize yield increase declined after average rainfall during the growing season in Belgium. Water retention curves of both soil types determined that the available water content was at least 11 percent higher in soils under black spots. Meanwhile, the delta C 13 analysis of maize leaves at final harvest, which was finalized following one season, showed that there was lower water stress for maize grown on black spots.

Despite the addition of biochar, the nutrient concentrations in maize leaves were unchanged. But adding historical charcoal had positive effects on soil cation exchange capacity (CEC), which is defined as a soil’s total capacity to retain exchangeable cations. Since CEC is an ingrained soil characteristic, it is near impossible to alter.

Testing also showed that soil with biochar contained traces of calcium (Ca) and magnesium (Mg).

The research team concluded that adding historical charcoal to fertile and temperate soils may boost maize yield due to the soil’s physical effects.

Fast facts on biochar and pyrolysis

Biochar is made via a process called pyrolysis.

  • Biochar is porous and it can be made from any kind of organic biomass.
  • During pyrolysis, the biomass needed to produce biochar is placed into a special oven that is heated with little to no oxygen. The process creates a stable solid material that is full of carbon content. Pyrolysis may occur under different temperatures that can produce various kinds of biochar, depending on the feed biomass utilized and the temperature reached in the pyrolysis process.
  • Biochar effectively captures carbon and locks it into the soil. (Related: Biochar – Enriching Your Soil & Saving the Planet!)
  • Upon analysis, the fertile dark earth soils from the Amazon River basin show that a form of biochar has already been used in agriculture for several centuries. The dark soils, called Terra Preta, contain a fine-grained and carbon-rich material. The material is formed when charred organic materials, including bones, crop residue, and manure, were added to the soil. Since modern kilns and ovens weren’t available at the time to create biochar, it’s possible that the ancient material was made by burning organic material that was covered with dirt to eliminate oxygen while also retaining the heat from the fire that baked the organic matter.

You can read more articles about the benefits of adding biochar to soil and how it can increase maize yield at

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