Modelling monthly NH3 emissions from dairy in 12 Ecoregions of Canada

Ammonia Emission in Poultry Facilities: A Review for Tropical Climate Areas

Brazil is the largest broiler meat exporter in the world. This important economic activity generates income in different branches of the production chain. However, the decomposition of residues incorporated in the poultry litter generates several gases, among them ammonia. When emitted from the litter to the air, ammonia can cause several damages to animals and man, in addition to being able to convert into a greenhouse gas. Thus, the aim of this article was to carry out a review of the ammonia emission factors in the production of broilers, the methodologies for measuring, and the inventories of emissions already carried out in several countries. The main chemical processes for generating ammonia in poultry litter have been introduced and some practices that can contribute to the reduction of ammonia emissions have been provided. The PMU, Portable Monitoring Unit, and the SMDAE, Saraz Method for Determination of Ammonia Emissions, with the required adaptations, are methodologies that can be used to quantify the ammonia emissions in hybrid facilities with a natural and artificial ventilation system. An ammonia emission inventory can contribute to the control and monitoring of pollutant emissions and is an important step towards adopting emission reductions. However, quantifying the uncertainties about ammonia emission inventories is still a challenge to be overcome.

Manure Flushing vs. Scraping in Dairy Freestall Lanes Reduces Gaseous Emissions

The objective of the present study was to mitigate ammonia (NH3), greenhouse gases (GHGs), and other air pollutants from lactating dairy cattle waste using different freestall management techniques. For the present study, cows were housed in an environmental chamber from which waste was removed by either flushing or scraping at two different frequencies. The four treatments used were (1) flushing three times a day (F3), (2) flushing six times a day (F6), (3) scraping three times a day (S3), and (4) scraping six times a day (S6). Flushing freestall lanes to remove manure while cows are out of the barn during milking is an industry standard in California. Gas emissions were measured with a mobile agricultural air quality lab connected to the environmental chamber. Ammonia and hydrogen sulfide (H2S) emissions were decreased (p < 0.001 and p < 0.05) in the flushing vs. scraping treatments, respectively. Scraping increased NH3 emissions by 175 and 152% for S3 and S6, respectively vs. F3. Ethanol (EtOH) emissions were increased (p < 0.001) when the frequency of either scraping or flushing was increased from 3 to 6 times but were similar between scraping and flushing treatments. Methane emissions for the F3 vs. other treatments, were decreased (p < 0.001). Removal of dairy manure by scraping has the potential to increase gaseous emissions such as NH3 and GHGs.

Key components and contrasts in the nitrogen budget across a US-Canadian transboundary watershed

Watershed nitrogen (N) budgets provide insights into drivers and solutions for groundwater and surface water N contamination. We constructed a comprehensive N budget for the transboundary Nooksack River Watershed (British Columbia, Canada and Washington, US) using locally-derived data, national statistics and standard parameters. Feed imports for dairy (mainly in the US) and poultry (mainly in Canada) accounted for 30 and 29% of the total N input to the watershed, respectively. Synthetic fertilizer was the next largest source contributing 21% of inputs. Food imports for humans and pets together accounted for 9% of total inputs, lower than atmospheric deposition (10%). N imported by returning salmon representing marine derived nutrients accounted for <0.06 % of total N input. Quantified N export was 80% of total N input, driven by ammonia emission (32% of exports). Animal product export was the second largest output of N (31%) as milk and cattle in the US and poultry products in Canada. Riverine export of N was estimated at 28% of total N export. The commonly used crop nitrogen use efficiency (NUE) metric alone did not provide sufficient information on farming activities but in combination with other criteria such as farm-gate NUE may better represent management efficiency. Agriculture was the primary driver of N inputs to the environment as a result of its regional importance; the N budget information can inform management to minimize N losses. The N budget provides key information for stakeholders across sectors and borders to create environmentally and economically viable and effective solutions.

How efficient is modern peri-urban nitrogen cycling: A case study

Urban centres acquire and accumulate many materials from their hinterland, among these are nutrient elements such as nitrogen (N). The popular North American vision of a peri-urban setting is one where urban food production, composting and re-cycling are assumed to limit urban accumulation of nutrients. This study quantifies this assumption using the Lower Fraser Valley (LFV) of British Columbia as an example, ideal because it is surrounded by mountains, ocean and an international border which collectively delimit the peri-urban boundaries. Nitrogen influxes are dominated by livestock feed imports to support dairy and poultry production (18000 tonnes N), followed by human food imports (9210 tonnes N), as well as 5410 tonnes N as fertilizer and 4690 tonnes N in atmospheric deposition. There is a transfer of 6700 tonnes N from agricultural to urban ecosystems displacing food imports, but food production contributes to the N footprint of the LFV. Nitrogen effluxes are dominated by sewage disposal (10400 tonnes N), solid waste disposal (7020 tonnes N) and atmospheric emissions (9460 tonnes N). The total influx is 15 kg N per person, the net influx is 3.1 kg N per person. Per unit land area, these are a total influx of 24 kg N/ha and a net influx of 4.7 kg N/ha. The atmospheric emissions are 4.7 kg N per person and 7.2 kg/ha. The N in soil is mobile and it is assumed soil N is at a steady state concentration, thus the surplus N is lost from the soil, probably by leaching and runoff. The Fraser River is estimated to acquire and transport 5230 tonnes N from the region into the ocean each year, in addition to 10300 tonnes N from sewage outfall. This is coupled with effluxes of phosphorus (estimated previously), and the result probably has an impact on the coastal waters. There is little reuse of imported N and current waste management practices including composting and combustion do little to improve N efficiency.

Methane and nitrous oxide emissions from Canadian dairy farms and mitigation options: An updated review

This review examined methane (CH4) and nitrous oxide (N2O) mitigation strategies for Canadian dairy farms. The primary focus was research conducted in Canada and cold climatic regions with similar dairy systems. Meta-analyses were conducted to assess the impact of a given strategy when sufficient data were available. Results indicated that options to reduce enteric CH4from dairy cows were increasing the dietary starch content and dietary lipid supplementation. Replacing barley or alfalfa silage with corn silage with higher starch content decreased enteric CH4per unit of milk by 6%. Increasing dietary lipids from 3% to 6% of dry matter (DM) reduced enteric CH4yield by 9%. Strategies such as nitrate supplementation and 3-nitrooxypropanol additive indicated potential for reducing enteric CH4by about 30% but require extensive research on toxicology and consumer acceptance. Strategies to reduce emissions from manure are anaerobic digestion, composting, solid–liquid separation, covering slurry storage and flaring CH4, and reducing methanogen inoculum by complete emptying of slurry storage at spring application. These strategies have potential to reduce emissions from manure by up to 50%. An integrated approach of combining strategies through diet and manure management is necessary for significant GHG mitigation and lowering carbon footprint of milk produced in Canada.

Greenhouse gas emissions intensity of Ontario milk production in 2011 compared with 1991

Jayasundara, S. and Wagner-Riddle, C. 2014. Greenhouse gas emissions intensity of Ontario milk production in 2011 compared with 1991. Can. J. Anim. Sci. 94: 155–173. For identifying opportunities for reducing greenhouse gas (GHG) emissions from milk production in Ontario, this study analyzed GHG intensity of milk [kg CO2 equivalents kg−1 fat and protein corrected milk (FPCM)] in 2011 compared with 1991 considering cow and crop productivity improvements and management changes over this period. It also assessed within-province variability in GHG intensity of milk in 2011 using county-level data related to milk production. After allocating whole-farm GHG emissions between milk and meat using an allocation factor calculated according to the International Dairy Federation equation, GHG intensity of Ontario milk was 1.03 kgCO2eq kg−1 FPCM in 2011, 22% lower than that in 1991 (1.32 kg CO2eq kg−1 FPCM). Greenhouse gas sources directly associated with dairy cattle decreased less (21 and 14% for enteric fermentation and manure management, respectively) than sources associated with feed crop production (30 to 34% for emissions related to N inputs and farm-field work). Proportions of GHG contributed from different life cycle activities did not change, with enteric fermentation contributing 46%, feed crop production 34%, manure management 18% and milking and related activities 2%. Within province, GHG intensity varied from 0.89 to 1.36 kg CO2eq kg−1 FPCM, a variation inversely correlated with milk productivity per cow (kg FPCM sold cow−1 year−1). The existence of a wide variation is strong indication for potential further reductions in GHG intensity of Ontario milk through the identification of practices associated with high efficiency.

Farm practices as they affect NH3 emissions from beef cattle

Sheppard, S. C. and Bittman, S. 2012. Farm practices as they affect NH 3 emissions from beef cattle. Can. J. Anim. Sci. 92: 525–543. Beef cattle farms in Canada are very diverse, both in size and management. Because the total biomass of beef cattle in Canada is larger than any other livestock sector, beef also has the potential for the largest environmental impact. In this study we estimate NH3 emissions associated with beef cattle production across Canada using data on farm practices obtained from a detailed survey answered by 1380 beef farmers in 11 Ecoregions. The farms were various combinations of cow/calf, backgrounding and finishing operations. The proportion of animals on pasture varied markedly among Ecoregions, especially for cows and calves, and this markedly affected the estimated NH3 emissions. The crop components of feed also varied among Ecoregions, but the resulting crude protein concentrations were quite consistent for both backgrounding and finishing cattle. Manure was stored longer in the west than in the east, and fall spreading of manure was notably more common in the west, especially when spread on tilled land. The estimated NH3 emissions per animal were relatively consistent across Ecoregions for confinement production, but because the proportion of animals on pasture varied with Ecoregion, so did the overall estimated NH3 emissions per animal. Temperature is a key factor causing Ecoregion differences, although husbandry and manure management practices are also important. Hypothetical best management practices had little ability to reduce overall emission estimates, and could not be implemented without detailed cost/benefit analysis.