Greenhouse gas and ammonia emissions from production of compost bedding on a dairy farm.

Recent developments in composting technology enable dairy farms to produce their own bedding from composted manure. This management practice alters the fate of carbon and nitrogen; however, there is little data available documenting how gaseous emissions are impacted. This study measured in-situ emissions of methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) from an on-farm solid-liquid separation system followed by continuously-turned plug-flow composting over three seasons. Emissions were measured separately from the continuously-turned compost phase, and the compost-storage phase prior to the compost being used for cattle bedding. Active composting had low emissions of N2O and CH4 with most carbon being emitted as CO2-C and most N emitted as NH3-N. Compost storage had higher CH4 and N2O emissions than the active phase, while NH3 was emitted at a lower rate, and CO2 was similar. Overall, combining both the active composting and storage phases, the mean total emissions were 3.9×10-2gCH4kg-1 raw manure (RM), 11.3gCO2kg-1 RM, 2.5×10-4g N2O kg-1 RM, and 0.13g NH3 kg-1 RM. Emissions with solid-separation and composting were compared to calculated emissions for a traditional (unseparated) liquid manure storage tank. The total greenhouse gas emissions (CH4+N2O) from solid separation, composting, compost storage, and separated liquid storage were reduced substantially on a CO2-equivalent basis compared to traditional liquid storage. Solid-liquid separation and well-managed composting could mitigate overall greenhouse gas emissions; however, an environmental trade off was that NH3 was emitted at higher rates from the continuously turned composter than reported values for traditional storage.

The epidemiology of reoperations for orthopaedic trauma.

INTRODUCTION: The Royal College of Surgeons of England (RCS) has issued guidance regarding the use of reoperation rates in the revalidation of UK-based orthopaedic surgeons. Currently, little has been published concerning acceptable rates of reoperation following primary surgical management of orthopaedic trauma, particularly with reference to revalidation. METHODS: A retrospective review was conducted of patients undergoing clearly defined reoperations following primary surgical management of trauma between 1 January 2010 and 31 December 2011. A full case note review was undertaken to establish the demographics, clinical course and context of reoperation. A review of the imaging was performed to establish whether the procedure performed was in line with accepted trauma practice and whether the technical execution was acceptable. RESULTS: A total of 3,688 patients underwent primary procedures within the time period studied while 70 (1.90%, 99% CI: 1.39-2.55) required an unplanned reoperation. Thirty-nine (56%) of these patients were male. The mean age of patients was 56 years (range: 18-98 years) and there was a median time to reoperation of 50 days (IQR: 13-154 days). Potentially avoidable reoperations occurred in 41 patients (58.6%, 99% CI: 43.2-72.6). This was largely due to technical errors (40 patients, 57.1%, 99% CI: 41.8-71.3), representing 1.11% (99% CI: 0.73-1.64) of the total trauma workload. Within RCS guidelines, 28-day reoperation rates for hip, wrist and ankle fractures were 1.4% (99% CI: 0.5-3.3), 3.5% (99% CI: 0.8%-12.1) and 1.86% (99% CI: 0.4-6.6) respectively. CONCLUSIONS: We present novel work that has established baseline reoperation rates for index procedures required for revalidation of orthopaedic surgeons.