PM2.5 and PM10 emissions from agricultural soils by wind erosion

• Crushed soil PM2.5 loss was 1.3–8.5 and PM10 1.9–10 times uncrushed soils.
• PM2.5 and PM10 loss increased with wind speed.
• PM2.5/PM10 ratios averaged 0.16 for soils crushed to <2 mm and 0.14 for uncrushed soils.
• No-till soil emissions were consistently lower than of conventional tilled soils.

Soil tillage and wind erosion are two major emission sources of particulate matter less than 2.5 and 10 μm in size (PM2.5 and PM10) from cultivated soils. Samples from fifteen cultivated soils from five states of the US, both crushed (<2.0 mm) and uncrushed (natural aggregation), were tested for PM2.5 and PM10 emissions in a wind tunnel, at 8, 10, and 13 m s−1 wind velocities. In addition, 10 soils were paired as conventional vs. no-till. Results showed that: (1) PM2.5 and PM10 emissions of crushed and uncrushed samples increased with wind speed, with a more rapid and greater emissions trend for crushed samples; after three wind speeds, mean PM2.5 and PM10 emissions from crushed soils were 1.3–8.5 and 1.9–10 times that of uncrushed soils; (2) PM2.5/PM10 ratios of crushed and uncrushed samples were, respectively, 0.11–0.45 and 0.13–0.46, and the mean PM2.5/PM10 ratio of uncrushed samples was higher; (3) PM2.5 and PM10 emissions of tested soils showed a significant negative power function relationship with clay content and PM2.5 and PM10 fractions of the dispersed soil samples, whereas the sand content and <0.42-mm aggregate content of the samples showed a significant linear positive correlation with emissions; and (4) although not significant, no-till soils had consistently lower PM2.5 and PM10 emissions than paired conventional tilled soils for uncrushed samples.