
Smart Weed
Whacker Takes Guesswork Out of SprayingBy Amy Spillman August 26, 2002In the not-too-distant future,
tractors already decked out with air conditioning units, CD players and global
positioning systems may be equipped with another handy gadget, according to
Agricultural Research Service scientists
and university cooperators. The gadget in question? An optical sensor that detects weeds and prompts a
herbicide sprayer to target them as the tractor drives up and down crop rows.
The technology means less herbicide in the environment and lower costs for
farmers. Most farmers now apply herbicides uniformly over a field, but weed
distribution is often patchy-particularly grass weeds in cereal crops.
Kansas State University graduate student
Ning Wang and KSU professor Naiqian Zhang, in collaboration with agricultural
engineer Floyd Dowell of ARS' Grain
Marketing and Production Research Center in Manhattan, Kan., and others
have developed an optical weed sensor and spray control system that takes the
guesswork out of herbicide application. Using a near infrared spectrometer, the researchers studied the light
absorption characteristics of weed stems and leaves. They identified five
wavelengths that can be used to discriminate weeds from crops and soil and,
with them, developed the optical sensor. The current model requires the tractor operator to spend about 5 to 10
minutes "training" the sensor to spot different weeds. The operator
does this by placing the sensor above a weed and typing in a "weed
code" on a simple keypad. Once the weed sensor has enough statistical
data, it prompts the operator to begin driving up and down the rows. If the
sensor detects weeds, the herbicide applicator will spray them. During laboratory tests, the sensor identified wheat, bare soil, and weeds
with accuracies approaching 100 percent. Although these results are promising,
the researchers believe it will be several more years before the system is
ready to be commercialized. ARS, the U.S. Department of Agriculture's
chief scientific research agency, provided funding for this research, as did
KSU, the National Science Foundation and the
Advanced Manufacturing Institute. U.S. Department of Agriculture |