Utilization of Portable x-Ray Fluorescence to Determine Nutrient Concentration of Poultry Litter at Varying Moisture Contents.

Poultry litter is a valuable amendment for many production systems. However, compared to other organic amendments, poultry litter can be a highly variable material. This is due to various feed and bedding material present in the material as well as the animal function. This high amount of variation can influence various nutrient components and cause problems during application. Portable x-ray fluorescence (PXRF) has been shown to accurately account for the amount of total nutrients in various material; however, limited information is available on utilization of this technology for poultry litter samples. Therefore, a trial was established to determine the feasibility of using PXRF to determine nutrient concentration as well as how moisture influences these nutrient readings.  Poultry litter samples were oven dried and scanned using the PXRF.  Following initial readings, increasing water contents (by weight) were added to create a moisture ramp from 10% to 50% gravimetric water contents.  Following scanning all samples were analyzed for total digestible nutrients through ICP-AES.  Overall, the relationship between ICP and PXRF varied based on nutrient analyzed, with the highest relationship between Mn and Zn (with r² = 0.61 and 0.60, respectively) and the worst relationship with K (with r² = 0.13).  Generally, the strongest relationship resulted in the scanning of dry poultry litter samples, with the exception of Fe which strongest relationship occur when scanning at 10% moisture.  The relationship between the PXRF scans and ICP analysis for K, Mn, Ca, and Zn significantly decreased with increasing moisture content.  This trend was not apparent for Fe and S, with little to no significant differences in the relationship from dry to 50% moisture.  Generally, the use of the PXRF show promise at being able to determine nutrient concentration of poultry litter; however, the inherent variability of the material limited stronger relationships.