2013 Annual Report
1)evaluate the magnitude, flux, and transport of PM emissions produced by agricultural practices for row crops where tillage CMPs are implemented vs. the magnitude, flux, and transport of PM emissions produced by agricultural practices where CMPs are not implemented;.
2)determine the control efficiencies of equipment used to implement the “conservation tillage” CMP; and.
3)assess whether CMPs for a specific crop can be quantitatively compared, controlling for soil type, soil moisture, and meteorological conditions. This study used advanced measurement technologies, which link lidar systems with conventional point-measurement air quality samplers, to map PM emissions at high spatial and temporal resolution in order to accurately compare CMPs with conventional tillage systems. The purpose of this field study was to determine if and how much particulate emissions differ between the conventional method of agricultural fall tillage and a conservation tillage CMP. An extensive network of measurement systems were used during this study, including a scanning lidar, a full meteorology suite, four sonic anemometers (for turbulence information), and filter and optical aerosol point samplers. Two additional aerosol chemical analysis systems were employed from a sampling trailer located on the downwind side of the field under test. Tillage particulate emission rates were determined using two methods:.
1)inverse modeling coupled with observed facility-derived concentrations from filter- and optical-based instruments; and.
2)a mass balance approach applied to upwind and downwind PM concentrations measured by the lidar. The tillage emissions were modeled using two different air dispersion models: the Industrial Source Complex Short-Term Model, version 3 (ISCST3) and the American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD). Emission data calculated for each measurement method for the conventional and conservation tillage operations are presented herein. The study showed that the conservation practice required <1/4 of the number of tractor passes when compared to conventional tillage; similar reductions in fuel use and tractor exhaust associated PM10 emissions were expected to have occurred. Lidar-derived and inverse modeling emission rates for PM2.5, PM10, and total suspended particulate (TSP) by operation, as well as the average tillage rate in hours per hectare are summarized herein. Based on lidar data, the conservation tillage method reduced PM2.5 emission by 91%, PM10 by 94%, and TSP by 91%, which were all statistically significant differences. Reduced emissions, as calculated using inverse modeling and optical particle counter data, are very close to lidar-derived reductions at 85%, 87%, and 90% for PM2.5, PM10, and TSP, respectively. The time per hectare required to perform the conservation tillage was about 14% of the conventional method. The control efficiency of the Conservation Management Practice for particulate emissions was 0.905, 0.937, and 0.909 for PM2.5, PM10, and TSP, respectively, based on lidar data and 0.853, 0.872, and 0.903 for PM2.5, PM10, and TSP, respectively, based on inverse modeling with optical particle counter data.