Burning straw this way into biochar can reduce atmospheric carbon
"Burning charcoal to cut carbon" sounds highly contradictory, yet there is much more to it than meets the eye. It turns out that in earlier years the charcoal produced when farmers burned rice straw and rice husks is known academically as "biochar"; as long as it is buried in the soil, it can capture carbon from the atmosphere and store it, forming alkaline biochar that can retain moisture, improve acidic soil, and make the soil healthier.
But with air pollution severe today, is it still appropriate to burn charcoal on site? The answer is no, but Pingtung University of Science and Technology says that as long as you use a covered iron gasoline drum, burn it in a low-oxygen way, and let it cool naturally after burning, you can both raise the charcoal yield and avoid air pollution; and to achieve a more refined, uniform product, National Formosa University and the Hualien District Agricultural Research and Extension Station have each made machines of different sizes for farmers' reference.
With a simple modification to an iron drum and the addition of a small chimney, charcoal can be made under low-oxygen conditions. (Photo / provided by Wang Chung-ho)
Biochar's effects need further study
However, since biochar comes from different sources, in theory the resulting biochar also performs differently, yet there is currently little in-depth or dedicated research on this in Taiwan, China.
Ni Li-feng said he has only tried mixing about 5 to 40% into the peat-based seedling medium for observation; among these, tomato and pumpkin seedlings both grow more slowly in the early stage and are not suited to excessive addition; but once the root system becomes robust later on, tomatoes can flower earlier, and pumpkins grow leaves and flower faster than those raised by farmers over the same period.
Chang Tzu-chien said that in theory different raw materials and temperatures will produce differences, but he is approaching it from a promotional angle, hoping farmers will use it directly on site to avoid transportation and carbon emissions from pursuing large-scale production, and has not yet carried out a more detailed analysis.
As for how to apply it, Wang Chung-ho said it only needs to be crushed and turned into the soil together with a cultivator; the optimal depth is 30 cm below the topsoil, though he said ordinary machines can probably only reach 10 cm, and fruit growers can also use biochar to improve soil quality.