Potential for Onsite and Online Analysis of Pig Manure using Visible and Near Infrared Reflectance Spectroscopy

In this research, the feasibility of a mobile spectroscopy instrument (Zeiss Corona 45 visnir fibre remote) in the visible (VIS) and near infrared (NIR) wavebands for onsite and online analysis of pig manure was investigated. The sensor was calibrated using the one-out cross-validation technique on a set of pig manure samples collected in the spring of 2004 and validated for its ‘true’ prediction accuracy on a set of samples collected in the spring of 2003 from different Flemish farms. Based on the values of coefficient of determination r2 and the ratio of standard deviation of validation set to root mean square error of cross-validation, the prediction results were evaluated as excellent for dry matter content, good for organic matter content and total nitrogen and approximate for ammonium nitrogen, phosphorus and magnesium. The calibrations for potassium and calcium were only able to discriminate between high and low values. These are encouraging results to recommend the VIS–NIR spectroscopy instrument for onsite measurement of manure composition. This sensor could promote a better manure management based on onsite or even online analysis during haul-out or soil application stages.