Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 3 Spectral signatures of objects. Chairman: G. Guyot, Liaison: N. J. J. Bunnik

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: The use of multispectral photography in agricultural research. J. G. P. W. Clevers

Document type:: Multivolume work

Structure type:: Chapter

228 sured. The subjective and qualitative nature of the first approach and the destructive sampling of a few plants, resulting in a large variability be tween measurements, of the second approach are the main disadvantages. Remote sensing techniques provide quantitative in formation about a whole field trial instantaneously and non-destructively. The aim of the research of this paper was to establish whether remote sensing can support and/or replace conventional field mea surements in field trials. Emphasis was on impro ving precision in field trials. 2 METHODOLOGY 2.1 Aerial photography Black and white multispectral aerial photography was carried out by taking vertical photographs from a single-engine aircraft, equipped with Hasselblad cameras with Planar 100 mm lenses, at intervals of about two weeks. A Minolta photometer was used for correcting the camera settings for differences in illumination between missions, and the expected reflectance level of the objects was also taken into account for obtaining correct levels of ex posure. Missions were only carried out under nearly con stant atmospheric conditions, and during a mission camera settings (exposure time and relative aper ture) were not altered for a certain film/filter combination. By a judicious choice of aerial films with satisfactory sensitivity used in combination with filters, the optimal wavelengths identified by Bunnik (1978) were matched: a green band (555-580 nm), a red band (665-700 nm) and an infrared band (840- 900 nm) (see Clevers, 1986a). The development of the films was standardized. Densities were measured by means of an automa tized Macbeth TD-504 densitometer with an aperture of 0.25 mm. After converting the densities to radi ant energy values by means of the characteristic curve, compensation for off-axis imagery was made for each image point (only for light fall-off; vig netting was avoided). There exists a linear rela tionship between this corrected radiant energy value and the reflectance of the object (Clevers, 1986a, 1986b). In this linear function the exposure time, relative aperture, transmittance of the optical system, irradiance, path radiance and atmospheric attenuation were incorporated. Reference targets with known reflectance characteristics were set up in the field during missions and recorded at the same camera setting and under the same atmospheric conditions as the field trials, in order to ascer tain the parameters of the linear function. Reflectance factors ascertained in this way with multispectral aerial photography appear to be well calibrated when compared with MSS and radiometers in the field (see Clevers, 1986b), supplying infor mation that is only influenced by the object. This allows multitemporal comparison and analysis. 2.2 Test area The research was carried out at the ir. A.P. Minder- houdhoeve, experimental farm of the Wageningen Agri cultural University (The Netherlands), situated in one of the new polders, Oost-Flevoland, which was reclaimed about 30 years ago. The new polders are flat, uniform and highly productive agricultural lands with a loamy topsoil. 2.3 Experiments The usefulness of remote sensing techniques in agri cultural research was verified by means of analysing several field trials. Field trial 116 in 1982: Barley in a split-plot de sign in three replicates (cultivar "Trumpf"). Whole- plot treatments were 2 sowing dates: 26 March (Zl) and 22 April (Z2). Split-plot treatments were 6 ran domized nitrogen levels: 0-20-40-60-80-100 kg N per ha (N1 to N6). Field trial 116 in 1983: Barley in a split-plot de sign in four replicates (cultivar "Trumpf"). Whole- plot treatments were 2 sowing dates: 7 March (Zl) and 21 April (Z2). Split-plot treatments were 5 ran domized nitrogen levels, applied as split dressing (in kg N per ha): before sowing Feekes stage 7 Total N1 0 0 0 N2 20 0 20 N3 20 20 40 N4 20 40 60 N5 20 60 80 For Feekes stages see Large (1954). Field trial 92 in 1982: Spring wheat in a split-plot design in three replicates (cultivar "Bastion", so wing date: 26 March 1982). Whole-plot treatments were 2 fungicide treatments: no fungicides at all (F0) and 4 kg Bavistin M per ha at Feekes stage 5 combined with 0,5 1 Bayleton per ha at stage 10.4 (FI). .Split-plot treatments were 2 sowing densities and 4 nitrogen levels, which were completely random ized within the whole plots. The sowing densities were: 150 seeds per m * 2 3 (SI) and 300 seeds per m 2 (S2). Only results for one nitrogen level will be presented (20 kg N per ha before sowing combined with 80 kg N per ha at F8). Field trial 92 in 1983: Winter wheat in a split-plot design in three replicates (cultivar "Arminda", so wing date: 25 October 1982). Whole-plot treatments were 2 fungicide treatments: no fungicides at all (F0) and 3 kg Bavistin M per ha at F5 combined with 2 kg Bayleton CF per ha at F10.4 (FI). Split-plot treatments were 3 sowing densities and 4 nitrogen levels, which were completely randomized within the whole plots. The sowing densities were: 150 seeds per m 2 (SI), 300 seeds per m 2 (S2) and 600 seeds per m 2 (S3). Only results for one nitrogen level will be presented (120 kg N per ha at F8). Field trial 95 in 1983: This trial was similar to field trial 92 in 1983. The cultivar of winter wheat was "Okapi" and the sowing densities were: 100 seeds per m 2 (SI), 200 seeds per m 2 (S2) and 400 seeds per m 2 (S3). Only results for one nitrogen level will be presented (40 kg N per ha before sowing combined with 100 kg N per ha at F8). 3 RESULTS 3.1 Spectral Reflectances In field trial 116 in 1982 reflectance factors were ascertained by means of multispectral aerial photo graphy in green, red and infrared spectral bands. The effects for two nitrogen levels for two sowing dates are illustrated in figure 2 for all three bands. In this figure the reflectance is plotted as a function of days after sowing. The patterns of green and red reflectances were similar. The re flectance in the visible bands decreased with in creasing growth during the beginning of the growing season. On the first recording date (28 April) only bare soil was present, resulting in similar reflec tance values in all spectral bands considered. At complete soil cover the reflectance in the visible bands remained fairly constant. At the end of the growing season this reflectance increased due to senescence of the crop. The sowing date effect was evident. The late-sown crop showed a faster develop ment due to higher temperatures during germination and initial growth than the early-sown crop, re sulting in a shorter growing season (shift in re sponse). There were significant (negative) nitrogen effects on reflectances in the visible bands, but the differences were small. For the infrared reflec- . a GREEN RE b RED REFL 20 15 10 0 0 c INFRARED 60 50 40 30 20 10 Z2 0 0 Figure 2 (c) infi and Z2) Field tr tance th was evic red spe( visible trogen i throughc In fie two nitr trated j sowing c was a ne (mostly season t frared r dates. I less prc In adc soil mo] son in moisture all thre tively j top soil the earl (for the tained c after s< spective

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