Near-infrared diffuse reflectance spectroscopy for the analysis of poultry manures

The objective was to evaluate near-infrared diffuse reflectance spectroscopy (NIRS) for determining the composition of poultry manures. Poultry manure samples were obtained from a commercial testing laboratory along with conventionally determined analyte values for total N, NH(4)(+)-N, organic N (computed as total minus NH(4)(+)-N), minerals, and moisture. Samples were blended in a food blender and scanned in polyethylene bags on a FOSS-NIRSystems model 6500 scanning monochromator. Initial results indicated that changes had occurred in NH(4)(+)-N contents from the time of analysis, and samples were reanalyzed for NH(4)(+)-N. Using the new analyses, NIRS was able to accurately determine NH(4)(+)-N, organic N, total N, and moisture in 128 poultry manures. Results were more accurate when determinations were made on an "as is" as opposed to dry matter basis. Finally, results indicated that NIRS was not suitable for the determination of minerals (P, K, Ca, etc.) in poultry manures.