November 1, 2023
minute read

Biochar Basics: Improving Organic Fertiliser

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. This not only decreases ammonia and greenhouse gas emissions from the manure, but can also reduce the amount of mineral fertiliser needed on farm. In this Biochar Basics, we talk about how you can use biochar to make the most of your manure.

Biochar 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. It can limit ammonia and N2O emissions in manure storage by up to 92% and 60% respectively. At a low dose rate of 1-3% by volume, emissions are expected to decrease in the range of 10-20%.

Biochar can also be used to make biocovers, which have been shown to reduce odour and capture nutrients when placed over open slurry stores.

Types of manure storage. From left to right: slurry tank, slurry lagoon, farmyard manure heap

What does Biochar do in Organic Fertiliser?

Improves nutrient retention

Biochar captures urea and ammonium on and within particles, preventing volatilisation, nitrification, and ammonification. This keeps more nitrogen available to crops.

Reduces environmental pollution

The physical and chemical structure of biochar prevents nutrient leaching and runoff. This ensures that nutrition is delivered more efficiently to crops, while protecting the air and waterways.

Enhances microbiome

Biochar improves the microbial environment within organic fertiliser, enhancing composting and nutrient retention.

💡Using Biochar Effectively

When applying biochar to organic fertilisers, dose rate, biochar properties and point of application must be considered to ensure it is compatible with your manure handling systems, and delivering optimal performance.

  • Applying the maximum concentration of biochar that is compatible with manure systems will increase the impact of biochar on nutrient retention and emissions reduction.
  • Minimising cultivation, or applying biochar after soil cultivation, will ensure crop roots can access nutrients held in biochar particles.
  • By adding biochar at different stages of organic fertiliser and manure management systems different emissions can be targeted.
  • Biochar properties can be altered to increase compatibility and performance.

Example Scenario: Reducing Mineral Fertiliser Use

On average, English dairy farms applied 116kg/ha of mineral nitrogen fertiliser and 40kg/ha of organic nitrogen in 2022. (National Statistics, 2023)

Biochar has been shown to increase the available nitrogen in organic fertiliser by 40%. (Agyarko-Mintah et al., 2017)

In this case, organic nitrogen availability would increase to 56kg/ha and mineral N requirement would decrease to 100 kg/ha. Here, biochar potentially reduces mineral nitrogen fertiliser use by 14%.

Biochar for Dairy Farms

At BBB, we are developing two biochar products designed for use on dairy farms – PinChar for slurry, and PelletChar for use in bedding and FYM. When mixed with muck, our biochar works to retain nutrients and make them available to crops once applied to land. Our products are designed to ensure biochar amended organic fertiliser can be applied as normal through spreading machinery.

Using PinChar in slurry
Using PelletChar in bedding and FYM
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