Near-infrared spectroscopic determination of carbon, total nitrogen, andammonium-N in dairy manures

摘要

The objective of this study was to investigate the feasibility of using near-infrared reflectance spectroscopy (NIRS) to determine nutrient concentrations in dairy manures. We assayed diverse dairy manures (n = 107), collected from dairy farms in the northeastern United States (CT, MD, NY, PA, and VA) 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-NIR-Systems Model 6500 scanning monochromator equipped with a sample transport device. We developed calibrations using a one-out cross validation procedure under partial least-squares regression. Preliminary results showed that eight samples were outliers either because of inaccurate conventional analysis or because they were uncharacteristic (i.e., two samples had moisture content below 72, while all others were above 78). These outliers were removed from further consideration. Final calibration results with the remaining 99 samples demonstrated that NIPS can accurately determine the moisture (r(2) = 0.945, root mean squared deviation or RMSD = 1.0), total C (r(2) = 0.950, RMSD = 0.40), total N (r(2) = 0.956, RMSD = 0.030), and NH3-N (r(2) = 0.967, RMSD = 0.013) concentrations, but not P or K concentrations in dairy manures. In conclusion, NIPS 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.