Amy M. Schmidt

Methane and carbon dioxide emission from two pig finishing barns.

Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed.

Quality-Assured Measurements of Animal Building Emissions: Particulate Matter Concentrations

Abstract Federally funded, multistate field studies were initiated in 2002 to measure emissions of particulate matter (PM) <10 μm (PM10) and total suspended particulate (TSP), ammonia, hydrogen sulfide, carbon dioxide, methane, non-methane hydrocarbons, and odor from swine and poultry production buildings in the United States. This paper describes the use of a continuous PM analyzer based on the tapered element oscillating microbalance (TEOM). In these studies, the TEOM was used to measure PM emissions at identical locations in paired barns. Measuring PM concentrations in swine and poultry barns, compared with measuring PM in ambient air, required more frequent maintenance of the TEOM. External screens were used to prevent rapid plugging of the insect screen in the PM10 preseparator inlet. Minute means of mass concentrations exhibited a sinusoidal pattern that followed the variation of relative humidity, indicating that mass concentration measurements were affected by water vapor condensation onto and evaporation of moisture from the TEOM filter. Filter loading increased the humidity effect, most likely because of increased water vapor adsorption capacity of added PM. In a single layer barn study, collocated TEOMs, equipped with TSP and PM10 inlets, corresponded well when placed near the inlets of exhaust fans in a layer barn. Initial data showed that average daily mean concentrations of TSP, PM10, and PM2.5 concentrations at a layer barn were 1440 ± 182 μg/m3 (n = 2), 553 ± 79 μg/m3 (n = 4), and 33 ± 75 μg/m3 (n = 1), respectively. The daily mean TSP concentration (n =1) of a swine barn sprinkled with soybean oil was 67% lower than an untreated swine barn, which had a daily mean TSP concentration of 1143 ± 619 μg/m3. The daily mean ambient TSP concentration (n = 1) near the swine barns was 25 ± 8 μg/m3. Concentrations of PM inside the swine barns were correlated to pig activity.

Development of irrigation scheduling tools for the humid, high-rainfall environment of the Lower Mississippi Delta

Irrigation in hot, humid areas is particularly challenging because irrigation must be applied in a timely manner to prevent yield loss due to crop water stress, yet avoid flooding should a rain event follow irrigation. Moreover, it is difficult to detect the onset of crop water stress under environmental conditions that limit evaporative cooling. The goal of this project is to develop reliable, easy to use irrigation scheduling tools that integrate crop monitoring and accurate weather predictions to improve the timing and application of irrigation in humid, high rainfall environments for better water management. The irrigation decision support system is based on calculations of crop water use from weather data collected from weather stations throughout Mississippi using crop coefficients developed from weighing lysimeters and other sources. A water balance approach is used to indicate when supplemental irrigation is needed based on available water and crop water use. This is integrated with other publicly available, spatially registered farm and soil databases to develop specific irrigation scheduling recommendations. A web-based interface is being developed to deliver the irrigation decision support system to producers through an easy to use and readily accessible format. Training materials will be developed and presented to producers through on-site training and other standard Extension mechanisms.

Spatial variability of heating profiles in windrowed poultry litter

SUMMARY In-house windrow composting of broiler litter has been suggested as a means to reduce microbial populations between flocks. Published time-temperature goals are used to determine the success of the composting process for microbial reductions. Spatial and temporal density of temperature measurement can influence the accuracy in determining what portion of a windrow section has achieved specified time-temperature goals. In this study, windrow section temperature was recorded every 2 min for 7 d on a 10 × 10-cm grid in 183 (width) × 91 cm (height) windrow sections. In 5 windrow sections, ordinary kriging was used to predict the mean portion of the windrow cross-sectional area reaching time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h. Based on these results, 88.5 ± 2.0%, 80.8 ± 3.9%, and 38.4 ± 11.7% of the windrow cross-sectional area can be expected to reach published microbial reduction time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h, respectively. This study illustrates the need to monitor temperature at multiple locations within windrowed litter to characterize heating profiles. Temporal and spatial sampling densities must be standardized to properly characterize temperature profiles in windrowed broiler litter. Additional research should be conducted to determine the degree of pathogen destruction achieved in the various time-temperature regions of the windrow pile. This study was useful in illustrating the efficacy (proportion of windrow cross-section) of windrow composting as a treatment method for reducing microbial populations as measured by time-temperature goals in used broiler litter.

Effect of Moisture Content on the Heating Profile in Composted Broiler Litter

Moisture content can affect the magnitude of heat generation during composting. Temperature was recorded every 2 min for 7 d at 10-cm increments throughout the vertical profile of broiler litter treated with five quantities of water addition. Water additions were applied to achieve litter moisture contents of 25, 30, 35, 40, and 45% MC w.b. Broiler litter moisture content between 30 and 35% was found to provide maximum heat generation during composting. Mean maximum temperature across all treatments was highest at the 10 and 20 cm litter depths. No moisture content treatment generated temperatures of required durations to meet all aspects of the EPA 503b rule for class B compost standards. Populations of total culturable aerobes, total culturable anaerobes and total culturable coliforms were enumerated in raw litter (time 1) and in treated litter after 84 h of composting (time 2) to determine if changes in population density were apparent. Over the 84 h composting period, a 4-log10 reduction in aerobes and coliforms was found for litter samples where a temperature of 40°C was sustained for as little as 4 h. Populations of total culturable anaerobes were reduced from time 1 to time 2, though the reduction was not physiologically relevant. The results demonstrate that incorporation of water to achieve a litter moisture content between 30 and 35% provides for greater heating during litter composting. Published time-temperature goals for pathogen reduction may not be achievable even with the added moisture, though relevant reductions in total culturable aerobes and coliforms were demonstrated with 84 h of composting.

Analysis of the Effect of Spatial and Temporal Sampling Densities on Accuracy of Predicting the Heating Profile in Windrowed Broiler Litter

A standard method for monitoring temperature in windrow piles of broiler litter to predict microbial population reductions is described. Temperature data collected every 2 min on a 10 cm x 10 cm spatial sampling grid in five identically-constructed litter windrow piles was utilized in this study. A Weibull distribution was fit to mean temperature response (MTR) curves of each pile. Curves were constructed at sample intervals parsed over a range of two to 1000 minutes. No difference in Weibull shape or scale parameters was observed among the analyzed sample intervals. A difference (P<0.05) in mean standard error of Weibull distribution fit parameters was identified between the 200- and 400-min sample intervals. Further analysis between the 200- and 400-minute sample intervals did not reveal a more appropriate value for optimal temporal sampling frequency. Optimal spatial sampling density was characterized using ordinary kriging analysis. Ordinary kriging was used to predict the cross-sectional areas of piles reaching specified time-temperature goals. Eight spatial sampling grid configurations were analyzed. Mean (n=5) predicted cross-sectional area (CSA) reaching 40°C for 120 h differed significantly (P<0.05) between the 30 cm x 20 cm and 30 cm x 30 cm grid spacing configurations. Accuracy of predicted pile CSA decreased as spatial sampling density decreased. This data will be beneficial when designing future windrow composting temperature monitoring studies.