One way to create manure biochar is to add biochar directly to manure. Manure biochar can enhance the effect as a fertilizer. In this process, the biochar is loaded and coated with the manure. Manure biochar can also be produced by using biochar in a previous step, for example in the form of animal feed, resulting in its inclusion in the manure. This way of application leads to an economic advantage due to the cascade utilization.
Advantages of Biochar in Manure
- Reduced use of mineral fertilizers
- Yield increase due to:
- Increased fertilizer effectiveness of the manure
- Long-term storage of plant-available nutrients
- Improved water storage capacity of the soil
- Soil aeration
- Initiation of humus formation and improvement of soil quality through increased microbial activity, aeration and pH adjustment
- Long-term fixation of nitrogen (odor minimization, reduced nitrate leaching, reduced water pollution)
Prevention of ammonia odors and water pollution, and other valuable benefits of manure biochar are due to the sponge-like, highly porous and ion-binding properties of biochar.
The odor reduction is due to the binding of ammonia to the large surface area of biochar. Biochar has a very high cation exchange capacity. Meaning, the surface of the biochar has a large number of binding sites for ions and electrons. Thus, nitrogen ions which are a part of nitrogen compounds such as ammonia (NH3) can be effectively bound. In addition, ammonia binding by manure biochar ensures the prevention of other problems caused by ammonia, such as acid rain. Furthermore, the biochar leads to the reduction of ammonium and nitrate leaching, which prevents soil acidification, eutrophication and groundwater pollution.
Due to the mentioned properties, nutrients can be excellently stored available for plants.
Long-term application of biochar can initiate humus formation and fosters the formation of permanent humus. 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.
However, biochar is not a panacea – applying biochar in agriculture has to be accompanied by soil-regenerative methods.
Degree of Development
Manure biochar is already available at many biochar manufacturers as a standardized product. Reliable research results already exist with regard to the optimal biochar parameters, the dosage as well as application methods. The application of manure biochar has increased within the past years, but is not yet widespread.
Application
Manure biochar is offered as powder or with a grain size between 0-15 mm. When applying the manure biochar into the manure, wind intensity and direction must be considered.
The application of the enriched manure in the field can be conducted with conventional methods, but techniques close to the ground, such as drag hose and chisel plough/lister, should be preferred.
It has been sufficiently verified that pure biochar can be used for manure application. The pure biochar should have a residence time of at least 8 weeks in the manure to become fully loaded. In addition to the pure biochar, pre-loaded manure biochars are offered, which have been loaded with, for example, lactic acid bacteria cultures.
Dosage
1 – 5 percent by volume of biochar are added to the liquid manure pit. This should be done at least 8 weeks prior to manure application to allow for loading of the manure biochar. Odor prevention sets in when 0.6 – 1 m³ of manure biochar is used per 100 m³ of manure.
Approval & Certification
Regarding approval and certification the same regulations as for soil 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 Version 10.1G vom 10. Januar 2022. 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).
In organic farming, the use of biochar as animal feed has also been approved in the EU since January 2020. Not all organic farming associations explicitly support the use of biochar. The Demeter label permits the use of biochar only as a composting aid in the form of organic fertilizer and as mulch material since January 2022.3Demeter (2022), RICHTLINIEN 2022,Erzeugung und Verarbeitung Richtlinien für die Zertifizierung »Demeter« und »Biodynamisch«. GÜLTIG AB 01. JANUAR 2022. Aufgerufen am 20.Juli 2022 von https://www.demeter.de/sites/default/files/richtlinien/richtlinien_gesamt.pdf#page=91
Sources
