Hot-spot reflectance measurements applied to green biomass estimation and crop growth monitoring

Hot-spot reflectance measurements applied to green biomass estimation and crop growth monitoring

Bunnik, N.J.J.
Verhoef, W.
de Jongh, R.W.
van Kasteren, H.W.J.
Geerts, R.H.M.E.
Uenk, D.
de Boer, T.A.

National Aerospace Laboratory NLR

1983-07-04

A new ground-based hot-spot reflectance meter (HSM) has been developed and tested for the estimation of green crop biomass and for crop growth monitoring. The concept of the HSM is based on theoretical studies on canopy hotspot reflectance measurements for a selected oblique illumination and view angle of 52° with respect to the vertical. A prototype HSM with a flash lamp as radiant source has been built by the Institute of Applied Physics TPD, Delft. Calibrated near infrared/red and red/green reflectance ratios are acquired which are related to changes of the green leaf area index and the colour characteristics of the canopy leaves. The advantages of the HSM are the independence of solar illumination conditions and the reduced sensitivity to the leaf inclination distribution function. A first measurement programme has been carried out during the 1982 season on winter wheat test fields. A preliminary analysis of the experimental data has demonstrated a good agreement with, reflectance model predictions. A significant relation between the near infrared/red ratio and the development of the leaf area index and the corresponding biomass has been found. This new method can improve the selection of samples for non-destructive assessment of standing biomass for agricultural research and crop production forecasting and estimation.

http://resolver.tudelft.nl/uuid:e794477b-6105-40c9-b1ad-808e7a49f108

Nationaal Lucht- en Ruimtevaartlaboratorium

Campus only

NLR MP 83037 U

Aerospace Engineering Reports

report

(c) 1983 National Aerospace Laboratory NLR