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Production of compost from cattle manure results in ammonia (NH 3) and greenhouse gas emissions, causing the loss of valuable nitrogen (N) and having negative environmental impacts. Lignite addition to cattle pens has been reported to reduce NH 3 emissions from manure by approximately 60%. However, the effect of lignite additions during the manure composting process, in terms of gaseous emissions of NH 3 , nitrous oxide (N 2 O), carbon dioxide (CO 2), and methane (CH 4) is not clear. This composting study was conducted at a commercial cattle feedlot in Victoria, Australia. Prior to cattle entering the feedlot, we applied 4.5 kg m−2 of dry lignite to a treatment pen, and no lignite to a control pen. After 90 days of occupancy, the cattle were removed and the accumulated manure from each pen was used to form two separate compost windrows (control and treatment). During composting we collected manure samples regularly and quantified gaseous emissions of NH 3 , N 2 O, CO 2 , and CH 4 from both windrows with an inverse-dispersion technique using open-path Fourier transform infrared spectroscopy (OP-FTIR). Over the 87-day measurement period, the cumulative gas fluxes of NH 3 , N 2 O, CO 2 , and CH 4 were 3.4 (± 0.6, standard error), 0.4 (± 0.1), 932 (± 99), and 1.2 (± 0.3) g kg−1 (initial dry matter (DM)), respectively for the lignite amended windrow, and 7.2 (± 1.3), 0.1 (± 0.03), 579 (± 50) and −0.5 (± 0.1) g kg−1 DM, respectively for the non-lignite windrow. The addition of lignite reduced NH 3 emissions by 54% during composting, but increased total greenhouse gas (GHG) emissions by 2.6 times. Total N losses as NH 3 –N and N 2 O–N were approximately 11 and 25% of initial N for the lignite and non-lignite windrows, respectively. The effectiveness of retaining N was obvious in the first three weeks after windrow formation. A cost-benefit analysis indicated that the benefit of lignite addition to cattle pens by reduced NH 3 emission could justify the trade-off of increased GHG emissions. • Lignite effects on gaseous emissions during composting of manure were examined. • A single OP-FTIR sensor and inverse-dispersion techniques were utilized. • Lignite amended manure decreased NH 3 emission by 54% during composting process. • CO 2 −e emission from lignite treated manure was 2.6 times that of non-lignite manure. • The benefits of reduced NH 3 by adding lignite outweighed increased GHG emission. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) emitted from concentrated animal feeding operations can cause environmental and health problems, and indirectly contribute to greenhouse gas emissions. Cattle feedlots are known to be large sources of NH 3 , but few studies have documented seasonal emissions from Australian feedlots. We conducted two field campaigns to measure NH 3 emissions from an intensive beef cattle feedlot in southeast Australia, and these results were combined with previous measurements at the same feedlot to document seasonal variations in emissions and to derive annual feedlot emission factors (EFs). Emission rates were calculated with an inverse dispersion modelling (IDM) technique, based on NH 3 concentrations measured at the feedlot with open-path lasers (OPLs). The average area emission rates in spring, summer, autumn and winter were 90.5, 167.4, 96.2 and 86.8 μg NH 3 m−2 s−1 from the cattle pens, and 22.5, 18.1, 7.7 and 20.7 μg NH 3 m−2 s−1 from the manure stockpile area, respectively. The total per-animal EFs ranged from 126.0 (autumn) to 190.2 g NH 3 animal−1 d−1 (summer), representing a loss of 47.5–64.6% of the fed N. Seasonal variations in emissions were related to air temperature. Slight changes in crude protein content of the cattle diet may also have impacted seasonal variability. Taking seasonal variations into consideration, the average feedlot EF was 160.4 g NH 3 animal−1 d−1, with 90% of the emissions coming from the cattle pens. Extrapolating the EF to all feedlot cattle in the country, the direct NH 3 emissions from Australian feedlots amount to 65.2 Gg NH 3 annually, or 3.7% of the national total. Our study benchmarks seasonal and annual EFs and N losses for Australian commercial feedlots, and provides a baseline for extrapolating the impacts of mitigation efforts. • Feedlot NH 3 emissions were measured during four seasons in Australia. • The average emission was equivalent to 160.4 g NH 3 animal−1 d−1. • Cattle pens were the main emission source (90%). • Ammonia losses accounted for 47.5–64.6% of the nitrogen in the cattle diet. • Feedlot NH 3 mitigation efforts should focus on cattle pens. [ABSTRACT FROM AUTHOR]

The emission and mitigation of nitrous oxide (N2O) from high nitrogen (N) vegetable systems is not well understood. Nitrification inhibitors are widely used to decrease N2O emissions in many cropping systems. However, most N2O flux measurements and inhibitor impacts have been made with small chambers and have not been investigated at a paddock-scale using micrometeorological techniques. We quantified N2O fluxes over a four ha celery paddock using open-path Fourier Transform Infrared spectroscopy in conjunction with a backward Lagrangian stochastic model, in addition to using a closed chamber technique. The celery crop was grown on a sandy soil in southern Victoria, Australia. The emission of N2O was measured following the application of chicken manure and N fertilizer with and without the application of a nitrification inhibitor 3, 4-dimethyl pyrazole phosphate (DMPP). The two techniques consistently demonstrated that DMPP application reduced N2O emission by 37-44%, even though the N2O fluxes measured by a micrometeorological technique were more than 10 times higher than the small chamber measurements. The results suggest that nitrification inhibitors have the potential to mitigate N2O emission from intensive vegetable production systems, and that the national soil N2O emission inventory assessments and modelling predictions may vary with gas measurement techniques. [ABSTRACT FROM AUTHOR]