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Article
Spectral Reflectance as a Covariate for Estimating Pasture Productivity and Composition
Crop Science
  • Alison B. Tarr, United States Department of Agriculture
  • Kenneth J. Moore, Iowa State University
  • Philip M. Dixon, Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
1-1-2005
DOI
10.2135/cropsci2004.0004
Abstract
Pasturelands are inherently variable. It is this variability that makes sampling as well as characterizing an entire pasture difficult. Measurement of plant canopy reflectance with a ground-based radiometer offers an indirect, rapid, and noninvasive characterization of pasture productivity and composition. The objectives of this study were (i) to determine the relationships between easily collected canopy reflectance data and pasture biomass and species composition and (ii) to determine if the use of pasture reflectance data as a covariate improved mapping accuracy of biomass, percentage of grass cover, and percentage of legume cover across three sampling schemes in a central Iowa pasture. Reflectance values for wavebands most highly correlated with biomass, percentage of grass cover, and percentage of legume cover were used as covariates. Cokriging was compared with kriging as a method for estimating these parameters for unsampled sites. The use of canopy reflectance as a covariate improved prediction of grass and legume percentage of cover in all three sampling schemes studied. The prediction of above-ground biomass was not as consistent given that improvement with cokriging was observed with only one of the sampling schemes because of the low amount of spatial continuity of biomass values. An overall improvement in root mean square error (RMSE) for predicting values for unsampled sites was observed when cokriging was implemented. Use of rapid and indirect methods for quantifying pasture variability could provide useful and convenient information for more accurate characterization of time consuming parameters, such as pasture composition.
Comments

This is an article from Crop Science 45 (2005): 996, doi:10.2135/cropsci2004.0004. Posted with permission.

Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Language
en
File Format
application/pdf
Citation Information
Alison B. Tarr, Kenneth J. Moore and Philip M. Dixon. "Spectral Reflectance as a Covariate for Estimating Pasture Productivity and Composition" Crop Science Vol. 45 (2005) p. 996 - 1003
Available at: http://works.bepress.com/philip-dixon/29/