Sources, Characteristics, and Management of Agricultural Dust, Central Valley, California, USA.

Crop production systems in California’s Central Valley are significant contributors to atmospheric dust, including PM10 (particulate matter with aerodynamic diameter less than 10 micrometers), and contribute to violation of US air quality standards during most years.  Field studies show that 1) conservation tillage practices in cotton-tomato rotations reduce PM10 by 50% or more, compared to conventional systems, 2) almond harvester modifications can reduce dust emission by about 80 to 90%, compared to conventional harvesters, and 3) commercial chemical dust suppressants effectively reduce dust production in almond orchards.  Dust mineralogy is similar to soil clay and silt mineralogy. Follow-up lab studies using a laboratory dust generator show that soil water content, soil texture, and soil aggregation all affect dust production.  High dust production occurs on soils with low water content, high silt/clay ratios, and low degree of aggregation.  We are developing a dust hazard rating for California soils based on soil survey data.