Remote 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.