By Rick Stowell and Galen Erickson et.al
Mitigation of manure-based methane on cattle operations is a topic of growing interest due to concerns about greenhouse gas emissions and safety in buildings with in-barn manure storage. No one approach works for all operations, of course, and strategies for mitigating manure-based methane emissions vary largely by the type of facility.
Mitigating emissions from open lots
Methane emission (per head or lb. of beef) from manure in a drylot setting is on the low end of the facility scale because the manure has a lot of exposure to air and aerobic environments don’t favor methane generation. Therefore, the over-riding management goal should be to maintain pens in desirable drylot condition – not allowing manure to build up, stay wet, and become anaerobic.
Dirt lots: Alternative strategies for managing a soil-based pen surface generally are conceived for other purposes – like controlling dust, reducing ammonia emission, or managing the cattle – and should be evaluated for potential negative consequences for methane emissions. For example, frequent pen cleaning could increase overall methane emissions if the harvested manure is stockpiled or stored for extended periods in wet condition.
Surfaced lots: When a pen is hard-surfaced – such as with roller-compacted concrete (RCC) – opposing factors affect methane emissions (↑ or ↓). Surfaced pens handle animal traffic and drain better than soil-based pens, which reduces mud development (↓). Since this lower risk for mud development also comes at greater capital cost, cattle are usually stocked at higher rates in surfaced pens, which in turn increases the rate of manure addition per square foot of pen surface (↑). While research on emissions from surfaced lots is needed, conceptually for the same cleaning frequency and weather, one should not expect much of a reduction, if any, in methane emissions with surfaced pens, and there could be an increase. Surfaced lots are much easier to clean, though, so harvesting manure frequently becomes feasible. Whether frequent cleaning of pens increases or decreases overall methane emissions likely comes down to how harvested manure is managed. Stockpiling or storing manure in wet condition probably would increase overall methane emissions, while drying, composting or digesting the manure could decrease feedyard emissions.
Source : unl.edu