Livestock produce large amounts of manure and this represents a valuable resource that, if used appropriately, can
replace significant amounts of chemical fertiliser. However, unless animal manure is managed carefully to minimise
odour, nutrient losses and emissions, it becomes a source of pollution and a threat to aquifers and surface waters. It can
also be a direct threat to human and livestock health. It is suggested that the development of reliable rapid and low cost methods for the assessment of manure nutrient content could encourage the uptake of improved techniques for the management and utilisation of livestock manure. Therefore the objective of this study was to provide a full evaluation and review of existing physicochemical models for predicting pig manure nutrient content using datasets compiled from various sources to test the validity of various physicochemical models. It was found that pig farmers could use easily determined properties, such as specific gravity, dry matter and electrical conductivity, to estimate pig nutrient content. The physicochemical method could not only achieve low-cost and rapid estimation of pig manure nutrient content, but could easily be understood by the farmers themselves.

For more information the full article can be found at  http://www.sciencedirect.com/science/journal/15375110