Methods used for sampling and analysing pig slurry: an on-farm survey

A telephone survey was conducted to review the various sampling and analysis techniques currently applied in pig farming. 97% of farmers from the 61 farms surveyed perform their own analyses to determine the composition of their slurry. In 66% of cases, sampling is performed by collecting a supernatant fraction from stirred slurry. Samples are taken when the slurry is homogenised before and (or) during slurry spreading. The validity of the sample depends not only on the efficacy of the slurry stirring, but also, for farmers taking samples after stopping the mixer, by the time before sampling. It was noted that 21% of farmers take their samples from the slurry spreader. Slurry is then analysed using a Quantofix (64% of cases) or Agro-lisier® (24%) volume meter. 50% of farmers use laboratory analysis as backup to these estimation methods, but only once-yearly or even once every two or three years.