Estimating potential dust emissions from biochar amended soils under simulated tillage

Although biochars may provide agricultural benefits, the potential risks related to agricultural dust emissions have not been adequately investigated. This study examines the impact of biochar type (WS 900: walnut shell, 900°C; PW 500, PW 700 and PW 900: pine wood, 500, 700, 900°C), biochar application rate (0, 1, 2, 5% wt.) and soil water content (low, medium and high) on dust emissions in two different textured-soils (silt loam, sandy loam). Dust was produced via a dust generator simulating soil disturbance (e.g, tillage) and dust fractions with an aerodynamic diameter under 100μm and 10μm (PM₁₀₀ and PM₁₀) were collected. The data indicate that the higher application rate of WS 900 led to higher PM₁₀₀ and PM₁₀ emissions while PW biochar treatments emitted equivalent amounts of dust as controls (non-amended soils). Dust emissions were exponentially reduced as soil water content increased, irrespective of biochar's presence. Specific markers for biochar, benzene polycarboxylic acids (BPCAs), were used to estimate the biochar content within dust. Results indicate that the increased dust emissions from WS 900 treatments mainly derive from soil particles due to the greater dispersion potential of WS 900 biochar. The collected data also reveal that PM₁₀ dust contains less biochar particles than PM₁₀₀, attributed to biochars originally containing negligible amounts of particles <10μm.