Intensive land preparation emits respirable dust

Respirable dust (RD), defined as particles smaller than 4 µm diameter, was collected at the implement from 29 farming operations performed for furrow-irrigated tomato, corn, and wheat crop production over a 2-year period. Land preparation, such as land planing, ripping, plowing, and disking, produced significantly higher concentrations of RD than most other cultivation operations. Land preparation accounted for 67% of all farming operations, but produced 82% of the RD. The number of operations and the timing of land preparation were responsible for the difference in RD concentrations among the seven 2-year crop rotations. Of the studied crops, tomato and corn were the most intensively cultivated and yielded the highest RD amounts. Soil moisture was an important environmental variable that influenced the amount of dust and the variability in dust concentration from sample to sample. Among the cropping systems studied, those that required more tillage or land preparation to be performed when the soil was driest produced the most RD.