Biochar is a carbon-rich material created by heating organic biomass, like wood, crop residues, or manure, in a low-oxygen environment—a process called pyrolysis. The result is a stable, charcoal-like substance that, when added to soil, can improve soil health, enable sustainable farming practices, and increase agricultural productivity.
Soil is improved when biochar is added to soil, with the effect depending on the soil type, biochar properties, and application rate. Biochar alters the soil in a complex manner, including improvements in soil pH, microbial activity, soil structure, and nutrient retention. Together, these effects result in a more resilient and productive soil.
Pyrolysis chemically transforms the carbon in biomass, which forms stable structures that are resistant to decomposition and decay. This means that, when biochar is added to soil, it can remain for hundreds to thousands of years. High-quality biochars made through controlled, high-temperature pyrolysis, are more stable and effective at locking up carbon.
Unlike other methods to increase soil organic carbon, such as green manures, biochar carbon does not require any maintenance or long-term changes to soil management. It can slow the decomposition of newly incorporated organic matter, such as carbon in organic fertilisers, enhancing soil carbon in a process called negative priming.
Biochar can be a powerful tool in protecting the environment within and around farms. Through sorption, biochar can decrease atmospheric ammonia emissions, limit nitrate leaching and runoff, decrease phosphate pollution and remediate contaminated soils effectively.
Nitrate leaching can be reduced by adding biochar to the bulk soil, as biochar decreases surface runoff and leaching from fertilisers. Not only does this protect surrounding waterways from nutrient pollution, but also ensures that valuable nitrogen is retained in the soil and accessible to crops. In temperate climates like the UK, studies have found that biochar can decrease nutrient runoff by up to 28%, limiting diffuse pollution and soil degradation.
When added to organic fertilisers like slurry or farmyard manure, or indirectly as a component of bedding, biochar can significantly improve its nutrient value to crops while decreasing carbon and nitrogen losses. It has been shown to increase the available nitrogen in organic fertiliser by 40%, and can also improve nutrient retention and crop uptake once it has been applied to land.
This not only decreases ammonia and greenhouse gas emissions from the manure, but can also reduce the amount of mineral fertiliser needed on farm. Biochar can also be used to make biocovers, which have been shown to reduce odour and capture nutrients when placed over open slurry stores.
Biochar is a valuable addition to animal bedding. When added to a base bedding material such as straw other mixed with sawdust, it can provide benefits including improved nutrient retention, decreased ammonia emissions, improved foot health and odour control. As an effective adsorbent, both organic molecules and mineral compounds stick to biochar surfaces and are retained. Keeping bedding clean and dry makes it more comfortable for the animals and improves hygiene. This reduces the risk of diseases such as mastitis and dermatitis, improving welfare and potentially livestock yield.
Biochar is highly porous at multiple scales, giving it a vast pore volume. This structure can absorb significant amounts of water and dissolved nutrients within the pore structure and between particles. Using biochar as a soil amendment can improve the water-holding capacity of soils and, eventually, plant available water by up to 28.5%.
The effects of biochar on soil water properties can improve crop resilience to water-related stresses, such as drought and flooding, which are becoming increasingly frequent as a result of climate change.
When used effectively, biochar can increase plant productivity and yield by up to 30%. It achieves this through a combination of increasing nutrient delivery, improving soil water properties, and promoting root development. Healthier soil and root systems means that crops can better access available nutrients and water in the soil. This reduces the need for additional inputs like mineral fertiliser. These changes to the soil environment can also limit environmental stresses to the crop and improve water use efficiency, which in turn improves productivity and yield.
Black Bull Biochar has a series of articles (Biochar Basics series), where they delve into each of these benefits in-depth, looking at the various properties of biochar, along with practical guidance for how to use it on-farm to maximise their impacts.
Agrecalc and Black Bull Biochar have collaborated to develop an innovative new biochar module. The impact of biochar on farm emissions can now be quantified using the updated model. This robust carbon reduction calculation is based on emission reduction factors that meet the protocol for including Mitigation actions in Agricultural Lifecycle Assessments (MiLCA).
The biochar module quantifies the impact of biochar on soil nitrous oxide emissions, a potent greenhouse gas with a global warming potential 273 times that of CO2. The impacts of biochar on other factors contributing to the farm’s overall carbon footprint, such as fertiliser use or yield, are captured indirectly through other modules.
The model allows the user to accurately assign the carbon storage of biochar depending on carbon credit ownership, protecting against double counting, and aiding farmers if other soil carbon pools are being allocated for carbon removal. The direct effects of biochar on other emission / negative emission factors are complex. Whilst biochar has been shown to positively influence soil properties and improve nutrient retention in organic fertilisers and bedding, these factors are difficult to model and may not directly reduce carbon emissions.
Black Bull Biochar (BBB) specialises in producing biochar, a nutrient-rich, carbon dense soil additive made from biomass. Produced through a process called pyrolysis, biochar is created by heating biomass in a low-oxygen environment. This securely locks the carbon within the biomass, preventing it from returning to the atmosphere for thousands of years.
Designed to enhance agricultural productivity, their biochar improves soil health, boosts crop resilience, and supports livestock welfare. SRUC and the UK Centre for Ecology and Hydrology ran independent field trials, trialling BBB’s tailored biochar products as an additive to organic fertilisers on dairy farms in the UK. The trials showed that low-dose biochar application resulted in an increase of 16% in annual grassland yield, and 22% in total soil nitrogen. The pyrolysis process also generates renewable heat and energy, which can be used in industrial applications.
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The Agrecalc team is looking forward to welcoming you at our stand (2.844) at this year’s Low Carbon Agriculture Show, taking place on March 5 and 6, at NAEC Stoneleigh near Kenilworth.
The harmonisation of carbon calculator methodologies has taken significant steps forward with two key developments: the establishment of an Industry Fertiliser Steering Group and the progress towards an interoperable data format. These initiatives aim to enhance the precision, usability, and impact of farm carbon calculators, benefitting farmers and the agrifood sector as a whole.
Agrecalc has launched new and improved Free Trial version of Agrecalc Cloud, with enhanced security measures.