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In a two-year study, com was subjected to controlled flooding during various physiological stages of growth by using specially constructed isolated field plots to determine how growth and grain yield were affected by excess soil water. Com was most susceptible to flooding at the early-vegetative stage (36 days after planting) with maximum reductions in plant-canopy height, dry-matter production, and grain yield. Two-year averages of the crop susceptibility (CS) factors calculated from the yield data were 0.64, 0.44, 0.15, and 0.19 for earlyvegetative, late-vegetative, flowering, and yield-formation stages of growth, respectively. The SDI concept was tested by comparing the relative yield-SDI relationships for a nearby area with naturally fluctuating water tables using CS values obtained in this study. The SDI models indicated a linear decrease in the relative yield with increasing wetness (SDI values), but the best-fit regression lines of the yield-SDI data for the undrained area differed considerably between years. Disciplines

Total suspended particulate (TSP) concentrations, ammonia (NH 3) concentrations, and ventilation rates were measured in four commercial, tunnel-ventilated broiler houses in June through December of 2000 in Brazos County, Texas. TSP and NH 3 concentrations ranged from 7,387 to 11,387 mg m-3 and 2.02 to 45 ppm, respectively. Ammonia concentration exhibited a correlation with the age of the birds. Mass median diameters (MMD) of the TSP samples were between 24.0 and 26.7 mm aerodynamic equivalent diameter. MMD increased with bird age. The mass fraction of PM 10 in the TSP samples was between 2.72% and 8.40% with a mean of 5.94%. Ventilation rates were measured between 0.58 and 89 m 3 s-1. Measured concentrations of PM 10 and ammonia were multiplied by the measured ventilation rates to calculate emission rates for PM 10 and ammonia. Ammonia emission rates varied from 38 to 2105 g hr-1. TSP emission rates and PM 10 emission rates ranged from 7.0 to 1673 g hr-1 and 0.58 to 99 g hr-1 , respectively. Emission rates for ammonia and particulate matter increased with the age of the birds. Most of the PM in the commercial broiler houses was large enough to be captured by the human or poultry respiratory system prior to being inhaled into the lungs.

There is a need for a robust and accurate technique to measure ammonia (NH3) emissions from animal feeding operations (AFOs) to obtain emission inventories and to develop abatement strategies. Two consecutive seasonal studies were conducted to measure NH3 emissions from an open-lot dairy in central Texas in July and December of 2005. Data including NH3 concentrations were collected and NH3 emission fluxes (EFls), emission rates (ERs), and emission factors (EFs) were calculated for the open-lot dairy. A protocol using flux chambers (FCs) was used to determine these NH3 emissions from the open-lot dairy. NH3 concentration measurements were made using chemiluminescence-based analyzers. The ground-level area sources (GLAS) including open lots (cows on earthen corrals), separated solids, primary and secondary lagoons, and milking parlors were sampled to estimate NH3 emissions. The seasonal NH3 EFs were 11.6 +/- 7.1 kg-NH3 yr(-1)head(-1) for the summer and 6.2 +/- 3.7 kg-NH3 yr(-1)head(-1) for the winter season. The estimated annual NH3 EF was 9.4 +/- 5.7 kg-NH3 yr(-1)head(-1) for this open-lot dairy. The estimated NH3 EF for winter was nearly 47% lower than summer EF. Primary and secondary lagoons (approximately 37) and open-lot corrals (approximately 63%) in summer, and open-lot corrals (approximately 95%) in winter were the highest contributors to NH3 emissions for the open-lot dairy. These EF estimates using the FC protocol and real-time analyzer were lower than many previously reported EFs estimated based on nitrogen mass balance and nitrogen content in manure. The difference between the overall emissions from each season was due to ambient temperature variations and loading rates of manure on GLAS. There was spatial variation of NH3 emission from the open-lot earthen corrals due to variable animal density within feeding and shaded and dry divisions of the open lot. This spatial variability was attributed to dispirit manure loading within these areas.

A protocol that consisted of an isolation flux chamber and a portable gas chromatograph was used to directly quantify greenhouse gas (GHG) emissions at a dairy and a feedyard operation in the Texas Panhandle. Field sampling campaigns were performed 5 consecutive days only during daylight hours from 9:00 am to 7:00 pm each day. The objective of this research was to quantify and compare GHG emission rates (ERs) from ground level area sources (GLAS) at dairy and cattle feedyard operations during the summer. A total of 74 air samples using flux chamber were collected from the barn (manure lane and bedding area), loafing pen, open lot, settling basin, lagoons, and compost pile within the dairy operation. For the cattle feedyard, a total of 87 air samples were collected from four corner pens of a large feedlot, runoff holding pond, and compost pile. Three primary GHGs (methane, carbon dioxide, and nitrous oxide) were measured and quantified from both operations. The aggregate estimated ERs for CH 4 , CO 2 , and N 2 O were 836, 5573, 3.4 g hd(collectively 27.5 kg carbon dioxide equivalent (CO 2 e) hd), respectively, at the dairy operation. The aggregate ERs for CH 4 , CO 2 , and N 2 O were 3.8, 1399, 0.68 g hd(1.7 kg CO 2 e hd), respectively, from the feedyard. The estimated USEPA GHG ERs were about 13.2 and 1.16 kg CO 2 e hd, respectively, for dairy and feedyard operations. Aggregate CH 4 , CO 2 and N 2 O ERs at the dairy facility were about 219, 4 and 5 times higher, respectively, than those at the feedyard. OPEN ACCESSAtmosphere 2011, 2 304At the dairy, average CH 4 ERs estimated from the settling basin, primary and secondary lagoons were significantly higher than those from the other GLAS, contributing about 98% of the aggregate CH 4 emission. The runoff holding pond and pen surface of the feedyard contributed about 99% of the aggregate CH 4 emission. Average CO 2 and N 2 O ERs estimated from the pen surface area were significantly higher than those estimated from the compost pile and runoff pond. The pen surface alone contributed about 93% and 84% of the aggregate CO 2 and N 2 O emission, respectively. Abatement and management practices that address GHG emissions from these sources will likely be most effective for reducing facility emissions.

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Total Ammoniacal Nitrogen -TAN (NH 3 + NH 4 + ) in wastewaters cause environmental degradation concerns due to their negative impacts on air, soil and water. Several technologies are available for TAN removal from the wastewaters. One emerging technology is the use of hydrophobic membrane as non-destructive NH 3 extraction. In this paper the authors discuss the uses of gas permeable membrane (GPM) and its physicochemical characteristics that influence gas mass transfer rate, diffusion and recovery mec hanisms of NH 3 from liquid sources (e.g. animal wastewater). Several aspects of NH 3 extraction from liquid manure and other TAN generation sources using GPM technology as well as its applicability for NH 3 mitigation from liquid effluents and possible recovery as a nutrient for plant growth are also discussed in this review.