|Reeves Iii, James|
|Reeves, V - CVM, FDA|
Submitted to: Proceedings of Pittcon Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2006
Publication Date: April 12, 2006
Citation: Reeves Iii, J.B., Dao, T.H., Reeves, V.B. 2006. Investigations into the potential of near- and mid-infrared diffuse reflectance spectroscopy for determining p in dairy manures [abstract]. Proceedings of Pittcon Meeting. Paper No. 1220-4P. Technical Abstract: While an important nutrient for plants, phosphorus is also an important nutrient source for algae blooms in our waterways. Increasing emphasis is being placed on regulating P input into our waterways from farm runoff. One important source of P in runoff is P in manures applied to soils. Previous efforts have demonstrated that near-infrared reflectance spectroscopy can accurately determine both ammonium- and organic-N in dairy manures, but regulations for such application are now being directed at P. As for N, P exists in both inorganic- and organic- forms in dairy manures, the primary organic form being phytic acid. Preliminary efforts at determining P in dairy manures using near- and mid-infrared spectroscopy, and a variety of standard analytical measures of P, have not resulted in satisfactory calibrations for either organic- or inorganic-P despite the fact that such P compounds are known to absorb in the mid-infrared spectral range. One potential reason for this is the presence of cations in dairy manures (Ca, Fe, Na, etc.) from animal diets and other sources. The objective of this research is to investigate the effects of cations on the spectral signatures of inorganic- and organic-P in dairy manures and their potential impact on both spectral calibrations and conventional analytical methods for P in manures. Results demonstrated that near-infrared spectra of phytic acid salts are relatively featureless when compared to their mid-infrared counterparts. However, in both cases, considerable spectral variation results from the attachment of different cations. With the many potential salts present in manures including mixed cation salts and even cross linking between phytic acid units, determining spectral signatures which can be used for calibration develop may be difficult or impossible as conventionally carried out. Similar effects on conventional assay methods likely further complicate calibration development.