Great Plains Agroclimate and Natural Resources Research Unit Site Logo
ARS Home About Us Helptop nav spacerContact Us En Espanoltop nav spacer
Printable VersionPrintable Version     E-mail this pageE-mail this page
Agricultural Research Service United States Department of Agriculture
Search
  Advanced Search
 
Programs and Projects
Subjects of Investigation
 

Title: ESTIMATION OF FORAGE NITROGEN CONCENTRATION AND IN VITRO DRY MATTER DIGESTIBILITY OF GRASS PASTURES USING PLANT CANOPY HYPERSPECTRAL REFLECTANCE

Authors

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2006
Publication Date: November 12, 2006
Citation: Starks, P.J., Zhao, D., Brown, M.A., Coleman, S.W. 2006. Estimation of forage nitrogen concentration and in vitro dry matter digestibility of grass pastures using plant canopy hyperspectral reflectance [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts, November 12-16, 2006, Indianapolis, IN. p. 266.

Interpretive Summary: ABSTRACT ONLY.

Technical Abstract: Timely assessment of forage nitrogen (N) concentration and in vitro dry matter digestibility (IVDMD) during the growing season can help livestock managers make decisions for adjusting stocking rate and managing pastures. Nondestructive measurements of pasture canopy hyperspectral reflectance may provide a rapid and inexpensive means for estimating these two nutritive variables. An experiment was conducted in the 2002 and 2003 growing seasons at the USDA-ARS, Grazinglands Research Laboratory to determine relationships between forage N and IVDMD and canopy reflectance of warm season grass pastures. Canopy reflectance from eight bermudagrass pastures was measured using a portable spectroradiometer. Laboratory chemical methods were used to determine forage N concentration and IVDMD. The reflectance data were used to develop and validate algorithms for estimation of forage N and IVDMD. Forage N concentration linearly correlated (r = 0.82, P < 0.0001) with a ratio of reflectance at 705 and 1685nm wavebands (R705/R1685) and IVDMD correlated with R705/R535 (r = 0.71, P < 0.0001). Multiple regression, band-depth analysis with stepwise regression, and partial least squares regression techniques enhanced the relationships between N and IVDMD and canopy reflectance values (0.81 |r| 0.90, P < 0.0001). However, validation of these equations indicated only slightly improved model efficiency for predicting the two forage nutritive values. Our results suggest that forage N concentration and IVDMD of bermudagrass pastures can be rapidly and nondestructively estimated during the growing season using canopy reflectance in a few narrow wavebands.

   
 
 
Last Modified: 05/25/2013
ARS Home | USDA.gov | Site Map | Policies and Links 
FOIA | Accessibility Statement | Privacy Policy | Nondiscrimination Statement | Information Quality | USA.gov | White House