Soil biochar is biochar that is applied directly to agricultural, horticultural or other green areas. The biochar must be loaded with a fertilizer before application.
Advantages of Biochar in Soils
- Restoration and upgrading of poor soils.
- Reduced use of mineral fertilizers
- Yield increase due to:
- Long-term storage of plant-available nutrients
- Improved water storage capacity of the soil
- Soil loosening
- Initiation of humus formation and improvement of soil quality through increased microbial activity, aeration and pH adjustment
- Long-term fixation of nitrogen (reduced nitrate leaching, water protection)
Many of these potentials are due to the sponge-like, highly porous, and ion-binding properties of the biochar.
As a result of the very high cation exchange capacity of the biochar, nitrogen ions which are a part of nitrogen compounds such as ammonia (NH3) can be effectively bound and thus nutrient leaching and water pollution can be prevented. The nutrients are stored in the soil in a form that is available to plants.
In addition, the biochar leads to the reduction of ammonium and nitrate leaching, preventing soil acidification, eutrophication and groundwater pollution.
Long-term application of biochar can initiate humus formation and fosters permanent permanent humus layers. However, this requires additional soil conservation management and regenerative methods, such as intercropping. The result is increased microbial activity, aeration, pH adjustment, and increased water storage capacity. This significantly increases soil resilience and quality.
Biochar is an effective way to store carbon in the long-term. Thus, the application of biochar in agriculture leads to negative emissions and carbon removal certificates (CORC) can be sold.
Degree of Development
Biochar for soil application is available from many manufacturers as a standardized product. Reliable research results already exist with regard to the optimal biochar parameters, the dosage as well as application methods. In Germany, Austria and Switzerland, more and more farms introduce the application of biochar on their agricultural land. In addition to biochar loaded with nutrient solutions, many farms also use fermented loading solutions containing useful microorganism cultures.
Application
Biochar for application in soils is offered as powder or in small-grain form. The biochar must be loaded with a fertilizer before it is applied. This is because pure biochar has a high cation exchange capacity and binds nutrient ions – it would therefore remove valuable nutrients from the soil. In addition to pure biochar, pre-loaded biochar is offered, which is loaded with lactic acid bacteria cultures, for example.
The loaded biochar is applied to the field conventionally, but techniques close to the soil, such as drag hoses and cultivators, should be preferred. Soil conservation is an important cornerstone for the positive effects of biochar on the crop, soil balance, permanent humus formation and long-term soil carbon stability.
Dosage
It is recommended to apply 2-10 percent by volume of biochar in relation to the top 20cm of the soil. This is done close to the seed/root, but with a minimum distance of 10cm. This does not include the volume of the loading material. However, the amount is very much dependent on specific conditions.
The dosage and concentration of the loading of the biochar is based on the nutrient quantities in fertilizers for the crop and region. The quantity must be determined individually.
Approval & Certification
Regarding approval and certification the same regulations as for manure biochar and litter biochar apply: If biochar is used for agricultural purposes, its harmlessness must be certified, as pollutants such as “PAHs, as well as dioxins and heavy metals, could enter the human food chain and accumulate permanently in soil.”1EBC (2012-2022) ‘European Biochar Certificate – Richtlinien für die Zertifizierung von Pflanzenkohle’, Ithaka Institute, Arbaz, Switzerland. http://www.european-biochar.org In Europe, a certification is offered by the European Biochar Consortium (EBC). Manure biochar for conventional agriculture requires the EBC-Agro certification standard, whereas organic agriculture requires the EBC-AgroBio standard, with the difference being stricter heavy metal and PAH limits for latter.2EBC (2012-2022) ‘European Biochar Certificate – Richtlinien für die Zertifizierung von Pflanzenkohle’, Ithaka Institute, Arbaz, Switzerland. http://www.european-biochar.org Version 10.1G vom 10. Januar 2022
The application of manure biochar is allowed in the EU as well as Switzerland. Biochar from wood and other organic biomass has been approved for use as fertilizer in the EU since July 2022 (updated EU Fertilizer Regulation 2019/1009).
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