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United States Department of Agriculture

Agricultural Research Service

Title: Analysis of Dairy Manures by Nir: Effects of Spectral Range and Fiber Optics on Calibration Accuracy

Authors
item Reeves Iii, James
item Van Kessel, Jo Ann

Submitted to: Pittsburgh Conference
Publication Type: Abstract Only
Publication Acceptance Date: March 7, 1999
Publication Date: N/A

Technical Abstract: The objective was to investigate the feasibility of using near-infrared or visible-shortwave near-infrared fiber optic based spectrometers to determine constituents of dairy manures. Manures (107) collected from dairy farms in the northeastern US were assayed conventionally and spectroscopically for total C and N, ammonia, moisture, P and K. Samples were scanned (64 co-added scans) on a NIRSystems Model 6500 scanning monochromator equipped with a fiber optic probe from 400 to 2498 nm, and on an Ocean-Optics model S2000 CCD spectrometer from 430 to 1100 nm (1000 scans/sample, integration time of 41 ms). Calibrations were developed using the one-out cross validation procedure under PLS. Results demonstrated that: 1. Accurate calibrations for ammonia, moisture, and Total C and N can be developed, but are not as accurate as those developed using a sample transport device; 2. Limitations in the spectra produced by presently available fiber optic bundles are at least partially responsible for the reduced accuracy found when compared to non-fiber optic means of sample presentation; 3. Spectra produced by fiber optic systems appear to be more diverse than those for non-fiber optic systems; 4. While determinations based on spectra covering the region from 400 to 2300 nm appear to be a viable alternative to other available quick tests for manure, those using only the 400 - 1100 nm spectral region do not; and 5. Further efforts with larger data sets are needed to determine the limitations and requirements for developing accurate and robust calibrations for manure constituents using fiber optic based spectrometers.

Last Modified: 4/20/2014
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