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ARS Home » Research » Publications at this Location » Publication #96531
Title: NIRS CALIBRATIONS FOR PREDICTING SOIL QUALITY PARAMETERS

Author
item CHENG, CHEN-WEN - IOWA STATE UNIVERSITY
item Laird, David
item MAUSBACH, MAURICE - USDA, NRCS
item HURBURGH, C - IOWA STATE UNIVERSITY

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/22/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Near-infrared reflectance spectra of 725 soil samples collected from 4 Major Land Resource Areas (MLRA) were studied to evaluate the effect of calibration procedures on the accuracy of NIRS-soil analysis. Locally weighted principle component regression (PCR) was used to correlate reflectance spectra with chemical and biochemical soil quality parameters. Preselection of potential calibration sets based on sampling area (MLRA, and State), sampling depth (surface and subsurface), and vegetation type were tested. The results indicate that the preselection procedures did not significantly affect the accuracy of the locally weighted PCR technique, as long as samples from the same MLRA were included in the potential calibration set (R2 of %C varies from 0.73 to 0.85; R2 of %N varies from 0.66 to 0.80). However, the accuracy of the PCR technique was decreased if samples from the same MLRA were excluded (R2 of %C is 0.55; R2 of %N is 0.52).