Agricultural News
Green Seeker Technology Determines Nitrogen Needs of Growing Crops
Wed, 21 Mar 2012 13:54:59 CDT
GREENSEEKER is the name of a relatively new technology just now finding its way into the hands of savvy farmers around the world. But more importantly, as it becomes more refined, the technology is becoming easier for farmers to handle and to afford.
Brian Arnall, Oklahoma State University assistant professor of soil fertility, works with precision soil nutrients and is the goto guy for GreenSeeker technology at OSU.
Development of the GreenSeeker techology is based on three factors, Arnall said.
"First, there are yield differences from year to year in all crops. Second, the amount of natural nitrogen available to crops varies from year to year. And plant nutrient needs are different each year," he said.
OSU scientists began working on ways to better determine nitrogen needs of growing crops during the 1990's, Arnall said. The first commercial sensor became available in 2002.
Using nitrogen-enriched strips planted across fields to be used with the sensor technology started in 2001-02, Arnall said.
Long-term research has proven the amount of nitrogen required to achieve maximum crop yields varies significantly from year to year. Reducing pre-plant nitrogen application and using the nitrogen rich strip to establish a rich nitrogen environment allows a mid-season check to see if any additional nitrogen needs to be applied to get top crop yields. Just as importantly, if none or only a small amount is needed, use of the GreenSeeker with the enriched strips helps a farmer save money, Arnall said.
Although GreenSeeker equipment, both hand-held units and larger variable-rate units are currently available, OSU agronomists are now working to make the technology available in hand-held units. Using one of these units, a farmer can walk across a field with and check the nitrogen levels in each field. Making the units smaller will also reduce the cost of them, he said.
As explained in a 2006 copy of Successful Farming, the GreenSeeker sensor is termed an active sensor because it generates its own light source rather than relying on ambient light. The sensor uses light-emitting diodes (LED) to generate red and near-infrared (NIR) light. The light is reflected off the crop and measured by a photodiode located at the front of the sensor head.
Red light is absorbed by plant chlororphyll during photosynthesis. Healthy plants absorb more red light and reflect larger amounts of NIR than unhealthy plants. The red light and NIR light readings from a crop, when compared to a nitrogen-rich calibration strip in the same field, are used to guage the crop's yield potential and nitrogen needs.
Growers using the system apply a reduced rate of nitrogen early, then topdress the crop based on what the GreenSeeker reveals about the crop during the growing season.
"We have GreenSeeker programs for winter wheat, corn, grain sorghum and cotton now," Arnall said. "Using a program developed in Canada for canola, we are adapting this program for use in growing canola in the Southern Plains."
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