Full TGIF Record # 20781
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Web URL(s):http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2494.1992.tb02258.x/epdf
    Last checked: 10/02/2015
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Publication Type:
i
Refereed
Author(s):Hutchings, N. J.
Author Affiliation:Macaulay Land Use Research Institute, Pentlandfield, Midlothian, UK
Title:Factors affecting sonic sward stick measurements: the effect of different leaf characteristics and the area of sward sampled
Source:Grass and Forage Science. Vol. 47, No. 2, June 1992, p. 153-160.
# of Pages:8
Publishing Information:Oxford, Blackwell Scientific Publications
Keywords:TIC Keywords: Reflectance; Research equipment; Surface levels; Ultrasonic rangefinders; Measurement
Abstract/Contents:"Laboratory experimentation found smooth and pubescent leaf surfaces to behave as specular (mirror-like) reflectors of ultrasound, whilst ribbed leaves behaved as an array of reflectors. It was concluded that swards composed of species with smooth, erectophile leaves would reflect ultrasound poorly and that this may explain the low sward height measurements returned by the sonic sward stick in the field when compared with the HFRO sward stick. The likely effect of species with planophile leaves such as clover is discussed. The sward surface influencing a sonic stick measurement was calculated to subtend a solid angle of about 43° at the transducer, equivalent to an area of about 1000 cm2 with the transducer mounted at a height of 50 cm. However, measurements made over turves of varying sizes or over turves with cores of varying size removed found the sensitivity decreased very rapidly beyond an inner area subtending a solid angel of about 7°; this is equivalent to an area of about 30 cm2."
Language:English
References:4
Note:Figures
Graphs
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Hutchings, N. J. 1992. Factors affecting sonic sward stick measurements: the effect of different leaf characteristics and the area of sward sampled. Grass Forage Sci. 47(2):p. 153-160.
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Web URL(s):
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2494.1992.tb02258.x/epdf
    Last checked: 10/02/2015
    Requires: PDF Reader
    Access conditions: Item is within a limited-access website
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MSU catalog number: SB 197 .B7
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