Sensing May Make Forage Analysis Faster, Easier
By Luis Pons
July 24, 2003
Matching grazing animals with the right
forage may soon be quicker and easier, thanks to remote sensing.
An Agricultural Research Service
study has revealed little difference between forage nutrient data collected
in the field by a portable lightwave reading machine and information obtained
through conventional lab analysis.
The one notable difference: remotely acquired information was ready for use
in hours, as opposed to the days it took to get the lab data.
The study was led by soil scientist Patrick Starks of ARS' Great Plains
Agroclimate and Natural Resources Research Unit in El Reno, Okla., and Samuel
Coleman of ARS' Subtropical Agricultural
Research Station in Brooksville, Fla. ARS is the U.S. Department of
Agriculture's chief scientific research agency.
According to Starks, whose unit is part of the
ARS Grazinglands Research Laboratory,
remote sensing may eventually provide realtime quality assessment and
nutritional landscape mapping of grazing lands. This can lead to improved range
and pasture management and better-informed harvesting decisions.
Current forage analysis uses near-infrared spectroscopy and chemical
procedures that, while accurate and site-specific, are time consuming. Remote
sensing collects data through detection and measurement of reflected or emitted
light, heat, sound and radio waves.
The research, conducted at El Reno, focused on Midland bermudagrass,
Cynodon dactylon, alone and with a scattering of other plants, and
compared how the two data-collecting methods detect concentrations of nitrogen
and other components.
The researchers used a handheld commercial hyperspectral radiometer that
measures reflectance in 252 wavebands of the electromagnetic spectrum to scan
plants and estimate their digestibility. After scanning, the plants were
collected and analyzed, for comparison, using traditional laboratory methods.
This approach will be tested later on other warm- and cool-season grasses.
Animal nutritionist William Phillips and animal geneticist Michael Brown of
the ARS Forage and Livestock Production Research Unit in El Reno are involved
in the study. Starks and 20 other scientists participated in an ARS review of
agricultural use of remote sensing that was published recently in the journal
Photogrammetric Engineering & Remote Sensing.