[compost_tea] Re: WEED DATABASE

From: Steve Diver <steved_at_ncatark.uark.edu>
Date: Sat, 23 Aug 2003 21:41:29 -0000

Kevin -

Using digital images in turfgrass research
is a new method. Some of this initial research
was done at the Univ of Arkansas Horticulture Dept,
which is across campus from where I work here
in Fayetteville, AR.

I've seen several posters on this technique,
for example, research on survival and spread of
different species of ground covers in low-maintenance
landscapes, so it has been adapted for different uses.

Here is a blurb from a Univ of Arkansas web
page that explains the use of digital imagery
in turfgrass research.

"Improving turf evaluations through digital image analysis"

"Techniques have been developed at the University of
Arkansas to precisely evaluate turfgrass cover and
color from the use digital images and specialized
software. Digital images of turf are initially scanned
by the software for pixels representing turfgrass.
Turfgrass pixels are then either compared to the remaining
number of pixels in the image to estimate percent cover,
or evaluated for hue, saturation, and brightness to
estimate turf color. This technology, which is a
significant improvement over traditional evaluations
consisting of subjective ratings, has been adopted
by several other university research programs abroad.
This research was financially supported by the O.J.
Noer Foundation and The Toro Company. In addition,
the National Turfgrass Evaluation Program is funding
additional research at the University of Arkansas for
using digital image analysis techniques to evaluate
turf characteristics such as density and uniformity,
so that when combined with percent cover and turf
color, an objective measure of turf quality may be
attainable."

Source:
http://www.uark.edu/ArkHort/research_programs/turf.html

      ++++++++++++++++++++++++++++++++++

To follow up on this technique and learn the digital
imagery procedures and software needed to analyze
the data, you can contact these professors:

Dr. Douglas Karcher, Assistant Professor
http://www.uark.edu/ArkHort/about_department/faculty/karcher.html

Dr. Mike Richardson, Associate Professor
http://www.uark.edu/ArkHort/about_department/faculty/richardson.html

      ++++++++++++++++++++++++++++++++++

Also,

Here is a news item from Univ of Arkansas, on this method

Greener Turf Through Digital Imaging
Date: September 2001
http://www.uark.edu/depts/agripub/Publications/Agnews/agnews01-61.html

Image:
http://www.uark.edu/depts/agripub/Publications/Agnews/ikemura21.jpg

Excerpt:

"Yoshi Ikemura, a graduate student in the horticulture
department in Bumpers College of Agricultural, Food and
Life Sciences, is correlating color of turfgrass, as recorded
by a digital camera, to application rates for nitrogen
fertilizer. His objective is to determine if digital image
analysis can quantify nitrogen levels in grasses commonly
used on golf courses.
 
"The trick is to get consistent color results that give us
accurate data for any plot of grass," he said. The digital
images are downloaded to a personal computer and analyzed
for average red-green-blue (RGB) values. From this data,
a "Dark Green Color Index" will be derived and correlated
to nitrogen use in test plots.
 
For his master's these research, Ikemura is using six
nitrogen rates on plots of bentgrass, bermudagrass
and zoysiagrass. Each plot is photographed weekly, then
clippings are weighed to determine growth rate and
analyzed for nitrogen content in the plant tissue.
Color is also evaluated visually for comparison.
 
"I'm looking for a standard in which a specific color
value for a given grass means it needs a specific amount
of nitrogen," Ikemura said."

      ++++++++++++++++++++++++++++++++++

Finally, if you get into the scientific literature, you
can find helpful papers for research protocals in journals
like HortScience, J. Am. Soc. Am. Hort, HortTechnology,
Weed Technology, Turfgrass journals, and Crop Science,
among others.

Here is an abstract for a paper by Karcher and Richardson,
in Crop Science journal.

Crop Science 43:943-951 (2003)
Quantifying Turfgrass Color Using Digital Image Analysis
Douglas E. Karcher and Michael D. Richardson
http://crop.scijournals.org/cgi/content/abstract/43/3/943

Abstract:

Color is a major component of the aesthetic quality of turf
and often evaluated in field studies. Digital image analysis
may be an improved, objective method to quantify turf color.
Studies were conducted to determine if digital image analysis
with SigmaScan software (SPSS, Chicago, IL) was capable of:
(i) accurately determining the hue, saturation, and brightness
(HSB) levels of Munsell Plant Tissue color chips,
(ii) quantifying visual color differences among zoysiagrass
(Zoysia japonica Steud.) and creeping bentgrass {Agrostis
palustris Huds. [= A. stolonifera var. palustris (Huds.) Farw.]}
plots receiving various N treatments, and (iii) quantifying
genetic color differences among bermudagrass (Cynodon spp.)
cultivars. Digital images of turf plots were analyzed with
SigmaScan software to determine average HSB levels for each
image. A dark green color index (DGCI) was created from HSB
values for direct comparison with visual ratings. Digital
image analysis accurately quantified the HSB levels
(r2 = 0.99, 0.96, and 0.97, respectively) of Munsell color
chips corresponding to turf colors. Significant HSB differences
were present among N treatments in creeping bentgrass, while
only significant hue differences existed in zoysiagrass.
Significant hue and saturation differences were present
among bermudagrass cultivars. There was strong agreement
between DGCI values and visual ratings. The relative variances
of the HSB and DGCI were significantly less than the variance
associated with multiple raters. This evaluation technique may
facilitate objective comparisons of turf color across
researchers, locations, and years when images are collected
under equal lighting conditions (i.e., the use of an artificial
light source at night or in an enclosed system).

Abbreviations: AS, ammonium sulfate • DAT, days after treatment
• DGCI, dark green color index • HSB, hue, saturation, and
brightness • NTEP, National Turfgrass Evaluation Program •
PCU,
polymer-coated urea • RGB, red, green, and blue • SCU,
sulfur-coated urea


Figure 5 in this paper explains it all. It displays
a digital image of the turfgrass, with a side-by-side
computer-generated HSB image with accompanying
digital numbers for H:, S:, B:

"Fig. 5. Color analysis of various turfgrass plots.
(A) The plot receiving the higher N rate has a darker
green color as a result of an increased hue angle
and decreased brightness level."

      ++++++++++++++++++++++++++++++++++

Also see:

Munsell: The Universal Language of Color
http://www.gretagmacbeth.com/Source/Solutions/munsell/index.asp

      ++++++++++++++++++++++++++++++++++

Also see:

Crop Science 41:1884-1888 (2001)
Quantifying Turfgrass Cover Using Digital Image Analysis
M. D. Richardson*,a, D. E. Karchera and L. C. Purcell
http://crop.scijournals.org/cgi/content/abstract/41/6/1884

Crop Science 40:704-709 (2000)
Method for Using Images from a Color Digital Camera to
Estimate Flower Number
F.J. Adamsena, T.A. Coffelta, John M. Nelsonb, et al
http://crop.scijournals.org/cgi/content/abstract/40/3/704

Crop Science, Vol 39, Issue 3: 719-724 (1999)
Measuring wheat senescence with a digital camera
FJ Adamsen, PJ Pinter, EM Barnes, RL LaMorte, et al
http://crop.scijournals.org/cgi/content/abstract/39/3/719

      ++++++++++++++++++++++++++++++++++

OK, that's enough to get a feel for what I'm
talking about.

As you can see, it is a dynamic tool.

Well, in retrospect this method is too much for
a grass-roots compost tea demonstration.

But at least this will get you tuned-in if you wish
to connect with any turfgrass researchers who can
support you with this kind of equipment and
analysis.

Best wishes,
Steve Diver
NCAT / ATTRA


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Received on Sat Aug 23 2003 - 19:19:21 EDT

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