Reducing Nutrient Leaching from British Agricultural Soils Using Biochar

Globally, commercial agriculture relies heavily on chemical fertilisers, with nitrogen being the most used nutrient. However, intensive fertiliser use degrades soil quality and contributes to nutrient pollution in waterways, leading to eutrophication and damage to aquatic ecosystems. Biochar is a specialised form of charcoal. It is a carbon-rich and porous material often used as a soil amendment. Incorporating biochar into soils may mitigate nutrient leaching, as well as reduce greenhouse gas emissions, sequester carbon, immobilise heavy metals, and improve the physicochemical characteristics of soil. The efficacy of a locally produced biochar is assessed on two British farm soils through a 55-day leaching column experiment with a 10% (by mass) application rate and synthesised chemical fertiliser. Biochar reduced nitrate and ammonium leaching by 75% and 90%, respectively. However, phosphate leaching increased. Biochar also reduced soil bulk density and neutralised pH. Soil type and history significantly influences biochar efficacy, alongside feedstock, pyrolysis conditions, and application rate. The findings suggest biochar can improve soil biogeochemical properties and reduce nutrient leaching, offering a potential solution to environmental and agronomic challenges in British agriculture. By addressing these issues, biochar could enhance sustainability in the industry.