Research Front: National Agricultural Manure Management Program – Greenhouse Gas Mitigation Options For Intensive Livestock Industries
On beef feedlot pen surfaces, underlying soil mixes with manure by animal treading, which causes problems for a raft of personnel involved in manure handling from composters to environmental scientists. We show that measuring soil-enriched elements like silicon in pen manure offers a simple and effective way to quantify manure/soil mixing. Our proposed approach could have significant practical benefits: for example, it could be used by feedlot operators to assess the quality of their composted manure products.
Layer-hen manure produces emissions of environmentally significant greenhouse gases and ammonia from manure stockpiles, which require mitigation. The present study compared greenhouse gas and ammonia emissions from uncovered storage with those from covered storage, to assess mitigation potential. Emission factors were calculated for ammonia and methane and mitigation of greenhouse gases and ammonia was achieved through covering layer-hen manure.
The pork industry is a small but significant contributor to agricultural greenhouse gas (GHG) emissions in Australia, with most emissions arising from manure management. The present study measured GHG emissions from a short hydraulic retention-time (HRT) effluent-storage system and a conventional long-HRT treatment in uncovered open ponds. Total GHG emissions were found to be 79% lower from the short-HRT system, potentially providing a GHG mitigation option for conventional pork production.
The majority of the greenhouse gas emissions from the Australian pork industry originate from manure management, and changes in management have the potential to significantly decrease these emissions. The present study measured methane, nitrous oxide and ammonia emissions from a deep-litter housing system and the stockpiled spent litter. The deep-litter system, when compared with conventional effluent pond systems, offers the opportunity of mitigating emissions by 66% and 80%, with and without a stockpile.
Greenhouse gas and ammonia emissions are important environmental impacts from meat chicken houses, and emission mitigation is a priority issue in Australian agriculture. This study compared emissions from meat chicken houses with two mitigation strategies, namely, increased litter depth and decreased dietary crude protein. Emission levels were found to be low from the control and mitigation trials, and reductions in ammonia were observed in response to reduced dietary crude protein.
A life-cycle assessment of greenhouse gas emissions from pork production was completed, investigating six supply chains and the national herd. Greenhouse gas emissions arose predominantly from manure management on conventional pig farms, with substantial emissions also arising from feed production and milling, and total emissions averaging 3.6 kg CO2-e/kg liveweight at the farm-gate for the national herd. Australian pork production generates moderate emissions with substantial opportunities for mitigation, particularly via improved manure management and particularly via generation of biogas and energy.
Composting is a popular way of managing organic residues, including animal manures, but it is not clear whether it also offers an opportunity for farmers to reduce greenhouse-gas emissions. Field measurements at a dairy farm showed higher emissions from composting of solid dairy manure than from stockpiling because some best management principles for composting were ignored, resulting in high gaseous nitrogen losses. Adequate incentives are needed for farmers to reduce nitrogen losses and minimise greenhouse-gas emissions.
