Monitoring grass swards using imaging spectroscopy

A.G.T. Schut, J.J.M.H. Ketelaars

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

The potential of an imaging spectroscopy system with high spatial (0.16-1.45 mm2) and spectral resolution (5-13 nm) was explored for monitoring light interception and biomass of grass swards. Thirty-six Lolium perenne L. mini-swards were studied for a total of eleven consecutive growth periods. Hyperspectral images and light interception (LI) were recorded twice weekly. On two dates ground cover was scored visually (GCV). At harvest, leaf area index (LAI), fresh-matter yield and dry-malter yield (DMY) were determined. Classification of images yielded several estimates of the image ground cover (GCi) and the index of reflection intensity (IRI). The GCi was highly correlated with GCV (r adj2 = 0.94), LAI (radj2 = 0.88) and LI (radj2 = 0.95, for dense swards under cloudy skies). However, the relationship between GCi and LI depended on sky conditions and sward structure. Under cloudy skies, LI was linearly related to GCi, whereas under clear skies, this relation was logistic. Regression analysis of GCi and yields showed correlations with r adj2 of between 0.75 and 0.82. The mean error of DMY estimates was 340 kg. In conclusion, estimates of GCi and IRI can be used to predict DMY, even for high yield levels (up to 3500 kg DM ha -1), allowing accurate, non-destructive monitoring of biomass and light interception of grass swards.
Original languageEnglish
Pages (from-to)276-286
JournalGrass and Forage Science
Volume58
Issue number3
DOIs
Publication statusPublished - 2003

Fingerprint

sward
interception
spectroscopy
grass
image analysis
monitoring
ground cover
leaf area index
hyperspectral imagery
biomass
clear sky
spectral resolution
Lolium perenne
logistics
regression analysis

Keywords

  • estimating herbage mass
  • rising-plate meter
  • capacitance meter
  • pastures
  • reflectance

Cite this

Schut, A.G.T. ; Ketelaars, J.J.M.H. / Monitoring grass swards using imaging spectroscopy. In: Grass and Forage Science. 2003 ; Vol. 58, No. 3. pp. 276-286.
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Monitoring grass swards using imaging spectroscopy. / Schut, A.G.T.; Ketelaars, J.J.M.H.

In: Grass and Forage Science, Vol. 58, No. 3, 2003, p. 276-286.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Monitoring grass swards using imaging spectroscopy

AU - Schut, A.G.T.

AU - Ketelaars, J.J.M.H.

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AB - The potential of an imaging spectroscopy system with high spatial (0.16-1.45 mm2) and spectral resolution (5-13 nm) was explored for monitoring light interception and biomass of grass swards. Thirty-six Lolium perenne L. mini-swards were studied for a total of eleven consecutive growth periods. Hyperspectral images and light interception (LI) were recorded twice weekly. On two dates ground cover was scored visually (GCV). At harvest, leaf area index (LAI), fresh-matter yield and dry-malter yield (DMY) were determined. Classification of images yielded several estimates of the image ground cover (GCi) and the index of reflection intensity (IRI). The GCi was highly correlated with GCV (r adj2 = 0.94), LAI (radj2 = 0.88) and LI (radj2 = 0.95, for dense swards under cloudy skies). However, the relationship between GCi and LI depended on sky conditions and sward structure. Under cloudy skies, LI was linearly related to GCi, whereas under clear skies, this relation was logistic. Regression analysis of GCi and yields showed correlations with r adj2 of between 0.75 and 0.82. The mean error of DMY estimates was 340 kg. In conclusion, estimates of GCi and IRI can be used to predict DMY, even for high yield levels (up to 3500 kg DM ha -1), allowing accurate, non-destructive monitoring of biomass and light interception of grass swards.

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KW - rising-plate meter

KW - capacitance meter

KW - pastures

KW - reflectance

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DO - 10.1046/j.1365-2494.2003.00379.x

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