Patrick A. Topper

Ammonia Emissions from U.S. Laying Hen Houses in Iowa and Pennsylvania

Ammonia (NH3) emission rates (ER) of ten commercial layer houses (six high-rise or HR houses and four manure- belt or MB houses) with different manure handling or dietary schemes were monitored for one year in Iowa (IA) and Pennsylvania (PA). Gaseous (NH3 and CO2) concentrations of incoming and exhaust air streams were measured using custom-designed portable monitoring units that shared similar performance to EPA-approved measurement apparatus. Building ventilation rates were determined by calibrated CO2 mass balance using the latest metabolic rate data for modern laying hens. The field monitoring involved a total of 386 and 164 house-day measurements or 18,528 and 7,872 30-min emission data points for the HR houses and the MB houses, respectively. The ER showed considerable diurnal and seasonal variations. The annual mean ERs (g NH3 hen-1 d-1) and standard errors were 0.90 ±0.027 for IA-HR houses with standard diet, 0.81 ±0.02 for IA-HR houses with a nutritionally balanced 1% lower crude protein diet, 0.83 ±0.070 for PA-HR houses with standard diet, 0.054 ±0.0035 for IA-MB houses with daily manure removal, and 0.094 ±0.006 for PA-MB houses with twice a week manure removal. Mass balance of nitrogen (N) intake and output performed for IA-HR houses revealed a total N intake recovery of 94% to 101%, further verifying the certainty of the NH3 ER measurements. Results of the study contribute to the U.S. national inventory on NH3 emissions from animal feeding operations, particularly laying hen facilities as affected by housing type, manure handling scheme, crude protein content of the diet, and geographical location.

Ammonia Emissions from Twelve U.S. Broiler Chicken Houses

Twelve commercial broiler houses in the U.S. were each monitored for at least thirteen 48 h periods over the course of one year to obtain ammonia emission data. Paired repetition of houses on four farms represents current construction with variety in litter management (built-up or new litter each flock) and climate conditions (cold or mixed-humid). Ammonia concentration was determined using portable electrochemical sensors incorporating a fresh air purge cycle. Ventilation rate was determined via in-situ measurement of fan capacity, fan on-off times, and house static pressure difference. There were seasonal trends in exhaust ammonia concentration (highest in cold weather) and ventilation rates (highest in warm weather) but not for emission rate. Flocks with at least three monitoring periods (13 of 22 flocks) demonstrated similar emission rates at a given bird age among the four study farms and across the seasons. An analysis of emissions from all houses on the three farms using built-up litter resulted in predicted regression slopes of 0.028, 0.034, and 0.038 g NH3 bird-1 d-1 per day of age; the fourth farm, managed with new litter, had the lowest emission rate at 0.024 g NH3 bird-1 d-1. The intercept of these composite relationships was influenced by litter conditions, with flocks on new litter having essentially no emissions for about six days while built-up litter flocks had emissions starting at flock placement. Data from all four farms and all flocks provided a regression slope of 0.031(±0.001 std error) g NH3 bird-1 d-1 per day of age. Emission rate per animal unit for built-up litter flocks indicated very high emissions for the youngest birds (under 14 days of age), after which time the emissions decreased exponentially and were then relatively steady for the balance of the flock cycle.

Ammonia and Greenhouse Gas Flux from Manure in Freestall Barn with Dairy Cows on Precision Fed Rations

Two lactating cow trials were conducted to evaluate the impact of diets differing in silage source (alfalfa/maize vs. grass/maize or maize/hay) and maize grain particle size (fine vs. coarse) on ammonia (NH3), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from a freestall barn floor with two groups of 60 cows each. In addition, the effects of environment (temperature, humidity) and management (manure depth, time since manure removal) factors were evaluated. Manure (feces and urine), spilled feed, bedding, and spilled drinking water were allowed to collect on the solid concrete, sloped barn alleys and were scraped twice a day. Gas fluxes from the freestall floor were measured at 64 locations over a 12 h period using a fast-response, non-steady-state flux chamber and an infrared photoacoustic gas analyzer during 18 trial days over a 9-month period. Fluxes of ammonia from manure on the barn floor were within average reported values for these 165 g kg-1 crude protein diets. All gas fluxes were similar (p = 0.253 to 0.977) regardless of silage source and maize grain particle size. The highest average ammonia emissions coincided with higher environmental temperature at 30 NH3 g AU-1 d-1, while the highest average greenhouse gas emissions from the manure on the floor were 10 g AU-1 d-1 for CH4 and 580 g AU-1 d-1 for CO2. Time in hours since scraping the floor had little impact on the production of ammonia, but greenhouse gas loss from the barn floor was reduced after scraping. Air and manure temperatures were positively correlated with emissions of NH3, CO2, and CH4 (p = <0.0001). NH3 (g AU-1 d-1) = (R2 = 0.38) for indoor air temperatures (Tair, °C) over the range from -5°C to 32°C (AU = 500 kg animal unit). Ammonia emissions were positively correlated with CO2 and CH4 gas emissions, suggesting that NH3 release from the manure was controlled to some extent by microbial activity and similar environmental factors. Nitrous oxide emissions remained <0.1 g AU-1 d-1 and were relatively constant for all diets and trials.

Field Estimation of Ventilation Capacity Using FANS

Instrumentation and procedures have been developed to characterize mechanical ventilation system capacity as part of an evaluation of ammonia emissions from commercial poultry housing. A FANS anemometer array unit, developed at the Mississippi USDA center, built and refined at University of Kentucky, and calibrated at the BESS laboratory, was found to have repeatability in the range of about 1% between two traverse readings performed one after the other. The unit was used to measure broiler house fans under typical system static pressure differences. A hydraulic lift cart was fabricated to streamline FANS positioning and movement through the large poultry houses. Taping all gaps between the FANS unit and fan housing improved airflow measurements about 6% versus not taping. Using a duct to transition down to 36-inch fans resulted in a 2.5% improvement versus not using a duct. Fan manufacturer performance data was 2 to 13% higher than actual field performance.

Validation of Ammonia Emissions from Dairy Cow Manure Estimated with a Non-Steady-State, Recirculation Flux Chamber with Whole-Building Emissions

A non-steady-state flux chamber with recirculation airflow was constructed and coupled with a portable photoacoustic multi-gas analyzer to determine ammonia emissions from dairy manure. The objective of this work was to validate this flux chamber system by performing a comparison between the flux chamber emission rates and whole-building emission rates calculated from an ammonia balance in a mechanically ventilated experimental test room. It was found that flux chamber emission estimates were greatly improved with the addition of internal air recirculation to provide air velocity over the enclosed manure surface. Validation tests of the recirculation flux chamber showed a 9% to 37% underestimation of the emissions calculated from the ammonia balance (R2 = 0.72). The non-steady-state, recirculation flux chamber method can be used to estimate ammonia emissions in naturally ventilated buildings with an accuracy comparable to other available methods. However, the validation tests showed high variability in the results, which is thought to be associated with the different consistency of the manure used in the experiments and the airflow dynamics over the enclosed manure surface.

Multiple-Chamber Steady-State Gas Emission Detection from Dairy Manure Slurry

In order to evaluate gas emission reduction potential of nutritional changes in lactating dairy cattle diets, an instrumentation system was developed to rapidly and accurately evaluate multiple treatments at one time. Six steady-state flux chambers were coupled via a multiplexer relay board and software with a photoacoustic multi-gas monitor to measure the concentration of ammonia and three greenhouse gases released from manure samples every 20 minutes over 24 hours. Each chamber sweep air flow rate was maintained at 0.5 air changes per minute via a calibrated flow meter. Five chambers evaluated emissions from manure samples consisting of 100 grams each of urine and feces from each cow on trial. This 50:50 urine:feces ratio produced as much or more ammonia gas than other ratios over 1 to 24 hour periods. The sixth chamber was filled with 200 grams of demineralized water for the initial gas concentration used in calculations. Emission was represented as the integral of gas released from the manure over a chosen time period. Results from five sub-samples of collected freestall manure had a standard error of 2% of the mean emission. Instrumentation use on manure slurry from trial cows was able to differentiate between diets but explanation of results may require additional information about other factors influencing gas emission. Results suggest that this method offers repeatable, simultaneous monitoring of gas emission from manure and offers potential to evaluate factors affecting emissions thus allowing better understanding and management of on-farm gas sources.

Ammonia Emissions from U.S. Tom Turkey Growout and Brooder Houses Under Cold Weather Minimum Ventilation

Ammonia (NH3) emission data in four tom turkey houses (two growout; two brooder) in Pennsylvania were monitored during winter 2003 and 2004. Data were collected during three 48-h periods for growout houses and during two 48-h periods for brooder houses. All houses were located at the same site, under contract to the same integrator, and managed by the same producer. Ammonia concentration was measured using electrochemical sensors in a portable monitoring unit; ventilation rate was determined using a fan assessment numeration system and fan run-time data. Mean NH3 emission rates for the growout house with used litter and the growout house with new litter were 2.3 and 0.98 g NH3.d-1.bird-1, respectively, for birds of ages 64 to 99 d. Expressed in terms of 500-kg animal units (AU), mean NH3 emission rates were 152 and 68 g NH3.d-1.AU-1, respectively. The 57% difference between the two NH3 emission rates was due to differences in litter total ammoniacal nitrogen concentrations and litter pH. For brooder houses, NH3 emission rates were not calculated because NH3 concentrations were less than the 1-ppm resolution of the electrochemical sensor. Daily variability in NH3 emission rates from a single growout house was relatively small compared to variability of NH3 emission rates between houses due to litter management differences. The mean NH3 emission rate for the growout house with used litter determined during this study was similar to the rate currently used by the U.S. Environmental Protection Agency; however, the NH3 emission rate for the growout house with new litter was 59% lower. Ammonia emission rates determined during this study apply to only growout houses with tom turkeys under cold weather minimum ventilation. Future work is recommended to determine NH3 emission rates from growout and brooder houses during mild and hot weather and from housing with hen turkeys.

Short Communication : Effect of Changing the Ratio of Forage to Concentrate on Ammonia Emissions by Dairy Heifers

Two animal growth studies and a companion digestibility study were conducted to evaluate the effect of differing ratios of forage to concentrate and the addition of yeast culture (Saccharomyces cerevisiae) on NH(3) emissions from the manure of growing dairy heifers with corn silage (CS) as the sole forage. Flux chamber methods were used to measure NH(3) volatilization from the barn floor or by laboratory procedures. In experiment 1, 24 Holstein heifers (159 +/- 3.3 kg of initial body weight; BW) were fed either a low-concentrate diet (LC; 77% CS, 23% concentrate) or a high-concentrate diet (HC; 33% CS, 67% concentrate) in a randomized design. Manure (feces and urine mixture) from heifers consuming the LC diets volatilized similar amounts of NH(3) as manure from HC heifers (314.0 vs. 174.4 +/- 36.1 microg/cm(2) per min). In experiment 2, 24 older heifers (227.9 +/- 27.1 kg of BW) were used. Manure from HC heifers released slightly less NH(3) from the barn floor, confirming the results from the initial study. Finally, a digestibility study was undertaken using four 9-mo-old heifers (234 +/- 15 kg of initial BW) and four 14-mo-old heifers (409 +/- 20 kg of initial BW), allocated to 4 treatments consisting of an HC or LC diet with or without yeast culture addition. Emissions per unit of manure (mg of NH(3)/g) from heifers in both age groups were greater for the HC diets; however, total emissions per day were equal. Yeast culture addition had no effect on cumulative daily emissions. In these 3 experiments, NH(3) emissions from HC heifers were not different from those from LC heifers.

Amendments for mitigation of dairy manure ammonia and greenhouse gas emissions: Preliminary screening

Amendments can be practical and cost-effective for reducing ammonia [NH3] and greenhouse gas [GHG] emissions from dairy manure. In this study, the effect of 22 amendments on NH3 and GHG carbon dioxide [CO2], methane [CH4] and nitrous oxide [N2O] emissions from dairy manure were simultaneous investigated at room temperature (20oC). Dairy manure slurry (2 kg; 1:1.7 urine:feces; 12% total solids) was treated with various amendments, representing different classes of product, following the suppliers’ recommended rates. In this screening of products, one sample of each amendment was evaluated along with untreated manure slurry with repeated measurements over 24 h. Gas emissions were measured after short (3 d) and medium (30 d) storage duration using a photoacoustic multi-gas analyzer. Six amendment products that acted as microbial digest, oxidizing agent, masking agent or adsorbent significantly reduced NH3 by >10% (P = 0.04 to <0.001) after both 3 and 30 d. Microbial digest/enzymes with nitrogen substrate appeared effective in reducing CH4 fluxes for both storage times. Most of the masking agents and disinfectants significantly increased CH4 in both storage periods (P = 0.04 to <0.001). For both CH4 and CO2 fluxes, aging the manure slurry for 30 d significantly reduced gas production by 11 to 100% (P <0.001). While some products reduced emissions at one or both storage times, results showed that the ability of amendments to mitigate emissions from dairy manure is finite and re-application may be required even for a static amount of manure. Simultaneous measurement of gases identified glycerol as a successful NH3 reduction agent while increasing CH4 in contrast to a digestive-microbial product that significantly reduced CH4 while enhancing NH3 release.

Ammonia and Greenhouse Gas Emissions from Dairy Freestall Barn Manure

Lactating cow trials were conducted to evaluate the impact of precision-fed diets at 16.5% crude protein but differing in silage source (alfalfa-corn vs. grass-corn or all-corn) and corn grain grind (fine vs. coarse) on emissions of ammonia (NH3), and greenhouse gases (GHG) [carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)]. Manure on the 120-cow freestall barn floor with gas fluxes measured at 80 locations over a 12-hour period using a non-steady-state flux chamber and an infrared photoacoustic gas analyzer during 18 trial days over a 6-month period. Air and manure temperatures were positively and highly correlated with emissions of NH3, CO2 and CH4. NH3 (g AU-1 d-1) = 1.7 + 0.12*Tair (oC) [R2=0.80] for indoor air temperatures (Tair) over the range of -5 to 32oC (1AU = 500 kg). Ammonia, CO2 and CH4 gas emissions were controlled to some extent by microbial activity and similar environmental factors. N2O fluxes remained <0.1 g AU-1 d-1. All gas fluxes were similar (p=0.054 to 0.860) regardless of silage source and corn grind. Highest average NH3 and CH4 fluxes were measured in the all-corn silage diet (also coincided with the higher environment temperature trials) with 6.3 g AU-1 d-1 for NH3 and 3.5 g AU-1 d-1 for CH4. The alfalfa-corn diet had the highest average CO2 emissions (111 g AU-1 d-1).