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United States Department of Agriculture

Agricultural Research Service

Title: Near-Infrared Spectroscopic Determination of Carbon, Total Nitrogen, and Ammonia in Dairy Manures

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

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2000
Publication Date: August 1, 2000

Interpretive Summary: Near Infrared Reflectance Spectroscopy (NIRS) is an instrumental method which uses light to determine the composition of materials such as forages. The objective of this study was to investigate the feasibility of using NIRS to determine nutrient concentrations in dairy manures. One hundred and seven diverse dairy manures, collected from farms in the northeastern US were assayed by conventional means and NIRS for total carbon, nitrogen, phosphorus, and potassium, and ammonia-nitrogen, moisture and pH. Preliminary results showed that 8 samples were bad due either to inaccurate conventional analysis or for being uncharacteristic (i.e., two samples had moisture contents below 72% while all others were above 78%), and were removed from further consideration. Final results using the remaining 99 samples demonstrated that NIRS can accurately determine the moisture, total carbon and nitrogen and ammonia-nitrogen, but not phosphorus or potassium contents of dairy manures. Results for pH were poor, but not totally useless. In conclusion, NIRS was shown to be a viable alternative to conventional analysis procedures for determining moisture, total carbon and nitrogen, and ammonia nitrogen in a very diverse set of dairy manures.

Technical Abstract: The objective of this study was to investigate the feasibility of using Near-Infrared Reflectance Spectroscopy (NIRS) to determine nutrient concentrations in dairy manures. One hundred and seven diverse dairy manures, collected from dairy farms in the northeastern US were assayed by conventional means and NIRS for total C, total N, NH3-N, moisture, P, K and pH. Samples were scanned from 400 to 2498 nm in polyethylene bags on a FOSS- NIRSystems Model 6500 scanning monochromator equipped with a sample transport device. Calibrations were developed using a one-out cross validation procedure using Partial Least Squares Regression. Preliminary results showed that 8 samples were outliers due either to inaccurate conventional analysis or for being uncharacteristic (i.e., two samples had moisture contents below 72% while all others were above 78%), and were removed from further consideration. Final calibration results using the remaining 99 samples demonstrated that NIRS can accurately determine the moisture (R2 = 0.945, RMSD = 1.0 %), total C (R2 = 0.950, RMSD = 0.40 %), total N (R2 = 0.956, RMSD = 0.030 %) and NH3-N (R2 = 0.967, RMSD = 0.013 %), but not P or K concentrations in dairy manures. In conclusion, NIRS was shown to be a viable alternative to conventional analysis procedures for determining moisture, total C, total N and NH3-N in a very diverse set of dairy manures.

Last Modified: 9/22/2014
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