- July 3, 2018
- In: Soil improvement, Insight
Can I use charcoal in my garden instead of biochar?
Public awareness concerning biochar-related information in Finland is still in the early stages. Discussions in online forums often speculate about applying charcoal to the soil in home gardens instead of biochar.
I do not recommend this: the end product of the combustion process – charcoal – is very different from biochar.
Biochar is produced by a process called pyrolysis, i.e., heating biomass in the absence of oxygen. Biochar obtained from pyrolysis has a porous structure, which is suitable for soil improvement in various ways. Charcoal, which is an end product of combustion, lacks both the unique structure and the plant growth-promoting properties of biochar.
Biochar and Rolling Stones
Using biochar, soil can be adjusted for specific goals and needs. In the early 1990s, the lawn and its seedbeds at the Helsinki Olympic Stadium were fortified with a mix of horticultural peat and sand. Unfortunately, biochar and its potential for soil improvement were unknown at that time.
The durability of the stadium’s lawn was put to test after a Rolling Stones’ concert. Over 10 000 concertgoers descended on the stadium on the night of the concert, and the main stage carried the weight of dozens of trucks worth of equipment. Consequently, the lawn sank by about 20–40 mm after the concert.
An international football game was scheduled to take place in the stadium on the weekend following the concert, and representatives of FIFA were coming to inspect the lawn. Thanks to some serious hard work, the stadium’s turf was repaired just in time for the inspection and the upcoming game.
If biochar was used instead of horticultural peat, such damage would have been significantly lesser, because the physical structure of biochar can withstand pressure better than that of horticultural peat.
Creating Terra Preta
Conventional farming practices and the use of chemical fertilizers have led to the formation of several areas around the world where the previously fertile soil is so depleted that it is essentially dead, where nothing grows anymore. Biochar works wonders in reviving soil and its microbes. It can help restore soil fertility and achieve the prerequisites of plant growth: nutrient-rich humus and microbes.
Similarly, applying biochar to heavy, clay soils would lead to a more porous soil structure, thus physically modifying the clay soil to promote plant growth. The porous structure of biochar offers a large surface area that allows bacterial colonization. Therefore, biochar is an excellent material for preparing compost. By following the methods of the ancient Amazonians, it is possible to create nutrient-rich humus or Terra Preta (“black soil” in Portuguese) in home gardens. Further, biochar could be used together with a dehydrating agent in a dry toilet, for example, in summer cottages.
Organic, organic, organic
To prepare soil for organic farming can take many years. Soil improvement specifically for organic farming takes long because the soil needs to meet several standards for organic production, such as only using non-chemical fertilizers. Biochar is a good soil amendment for land that is being prepared for organic farming. It improves the physical and chemical properties of soil while adhering to the standards required for organic farming.
The biggest challenges in using biochar are related to its supply and the lack of established standards that define biochar as a product. The standardization process is yet ongoing, both at the level of the European Union and in Finland. Until the product standards for biochar have been finalized, consumers need to be aware of what to buy and what not to buy as biochar. It is important to familiarize yourself with the background of the biochar vendor and verify the biochar manufacturing process.
This way, one can avoid mistakes like adding ash and charcoal to the soil instead of actual biochar.