Recently published scientific research into slurry storage and treatment has revealed that the release of dangerous levels of Hydrogen Sulphide or harmful slurry gas often caused by mechanical mixing can be avoided where aeration systems are utilised.
The research, which was undertaken by the Agricultural Research Institute of Northern Ireland and Teagasc Grange Beef Research Centre, demonstrates the health and safety and economic benefits of using an air mixing or aeration system over conventional methods of slurry conditioning.
In 2003 the Agricultural Institute and Teagasc undertook an investigation into hydrogen sulphide gas levels in cattle houses during mechanical slurry agitation. The results concluded that during agitation there was no safe tank, since Hydrogen Sulphide was always produced at varying concentrations and durations. It was recommended that operators should not enter buildings and that livestock should be removed from buildings during agitation.
In 2006 further research at Teagasc Grange examined the effectiveness of utilising an aeration system for slurry treatment and revealed a drastic reduction in potentially harmful emissions with no risk to operators or livestock.
During the trials in 2006, the Institute installed an aeration system in three below-slat tanks which were monitored over a 99 day period against three identical tanks without an aeration system. The aeration system essentially bubbles air through the slurry, keeping it fluid.
Throughout the experiment the Hydrogen Sulphide emissions were carefully monitored in all six pens which were occupied by the same number of beef cattle, being fed an identical diet.
Results of the trial revealed that where the aeration system was applied there was no health risk to stock or workers with minimal Hydrogen Sulphide (<5ppm) emitted during mixing and (<7ppm) during pumping slurry out of the store. The slurry was maintained in a homogenous state with no loss of Nitrogen or reduction of other nutrients.
In comparison, during mixing and pumping of the non-aerated slurry Hydrogen Sulphide emissions were recorded up to 257ppm, well above the recommended safe level of <15ppm.
During the trials in 2006, the Agricultural Research Institute installed a Milbury Systems Aeromixer slurry conditioner which operates on a single phase 1.85kW/hr compressor system. The Aeromixer runs for a short time each night on off peck electricity, maintaining the slurry in an easily handled consistency throughout the store so that it is ready to spread at any time with a uniform distribution of nutrients.
