Annals of Environmental Science
Volume 1, August 2007, Pages 69-79
Rapid Composition and Source Screening of Heterogeneous Poultry Litter by X-Ray Fluorescence Spectrometry
T. H. Dao and H. Zhang, USDA, ARS, BARC, Beltsville, MD 20705, and Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 73704, USA.
Received May 14, 2007; in final form July 9, 2007; Accepted July 19, 2007
Variability in composition has limited the predictability of manure nutrient availability and crop responses, reducing the value of poultry litter as a fertilizer in production agriculture. Current analytical methods are not conducive to rapid analysis of a large number of replicates of such heterogeneous materials that is needed for improving accuracy of land application rates and optimal allocation of manure-borne constituents on the farm. Seventy-one litter samples were collected across poultry producing regions of Arkansas, Oklahoma and Maryland to evaluate the application of energy dispersive x-ray fluorescence (EDXRF) spectrometry for fast and accurate multi-elemental analysis and screening of manure types. The total phosphorus (P) results by the phosphomolybdate-ascorbic acid, and EDXRF methods were correlated, with a root mean square error (RMSE) of 1.4 g kg-1 between methods. Energy dispersive XRF and inductively coupled plasma atomic emission spectrometric results for P, sulfur (S), potassium (K), calcium (Ca), manganese (Mn), copper (Cu), zinc (Zn), and arsenic (As) also were well correlated (P < 0.001). A successful differentiation was made between layer and broiler litter, based on Ca and As concentrations. The results suggest that the EDXRF pressed disc method is an accurate alternative to individual wet chemistry methods due to its simplicity, while for instance providing corollary knowledge of other components that affect speciation and bioavailability of P. Timely knowledge of litter mineral composition may result in more frequent manure analysis to assist in efforts to maintain optimal manure nutrient balance on the fields. A high throughput allows more extensive measurements of nutrient accumulation on regional and larger spatial scales.