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Power at Work
Variable rate fertility program offers big savingsGreenSeeker is easy to use and, tests show, it can substantially reduce the amount of nitrogen needed on your fields by JOHN DIETZ Technology that applies a variable rate fertility program on the fly and without GPS has been introduced on a limited basis in Ontario and Quebec. Tests suggest that it can help farmers reduce the amount of nitrogen they need to apply to their fields, and it has shown big potential when tried by two farming brothers in Manitoba. GreenSeeker an electronic device developed by Oklohoma State University researchers uses light-emitting sensors and software to read the health and size of a standing crop. An applicator can top-dress nitrogen at variable rates while travelling up to about 16 km/h. Hand-held units are also available. The first private system in Canada was used in southwest Manitoba in 2006. A second unit has been used in a program with Agriculture and Agri-Food Canada (AAFC) at Indian Head, Sask. “In all cases that we’ve analyzed so far, we have shown we could economically reduce the amount of nitrogen applied without affecting grain yield,” says AAFC research scientist Guy Lafond. “It’s easy technology to use. Once we get the algorithms developed, growers will just have a spreadsheet and plug in the sensor values. You put that in your machine, and away you go.” A University of Guelph team and researchers from the Ontario agriculture ministry began working with GreenSeeker units in 2006. Testing is underway in corn and winter wheat crops in Ontario and Quebec. Initially, growers apply a starter rate of nitrogen ranging from 20-50 lbs of nitrogen per acre. On each field, they do several full-rate test strips. A few weeks later, GreenSeeker compares reflectance from the standing crop with reflectance from the test strips. Algorithims determine the amount of nitrogen required to bring the standing crop to maximum yield potential. It then signals a flow controller on the applicator to apply the correct amount of additional nitrogen at that position in the field. It will vary the rate from zero to 70 lbs per acre in wheat and canola. Compared to the full rate, Agriculture Canada saved $5 to $10 an acre on the variable rate treatments while maintaining yields. “The efficiency of the fertilizer increased with the variable rate applications,” Lafond says. “It has tremendous potential. Our results to date show that, in most cases, even if you don’t increase yields, the fertilizer savings will pay for the application.” Darrel and Darcy Carlisle of Souris, Man., had immediate payback when they tried GreenSeeker. They had 4,300 acres of wheat in intensive management and their 2005 program called for approximately 100 lbs. of nitrogen across the farm. They side-banded 60 per cent as a base rate. GreenSeeker surprised them. When it did the comparison, it indicated they had nothing to gain by applying any more nitrogen. “The calibrations were telling us the field had more than enough N already, so we didn’t need to apply the 40 lbs. we’d planned,” Darrel says. The brothers confirmed their interpretation with GreenSeeker’s developers at Oklahoma State University. Tissue tests confirmed the crop had more than enough nitrogen. Still, they applied the planned full rate on strips in some fields to see what would happen. The 3,000 acres of wheat with only the initial fertilizer averaged 65 bushels an acre. The strips with the full rate matured two weeks later, had more disease and averaged a 55-bushel yield. “They cost me $14 an acre more for fertilizer, cost me $4 more for the application, and cost me 10 bushels of wheat,” says Darrel. Nitrogen was at 40 cents a pound. If the Carlisle brothers had applied full rate on the 3,000 acres of wheat, they would have invested approximately $48,000 in fertilizer they didn’t need, plus $12,000 for the application. And they would have failed to realize about 30,000 bushels in yield potential. Their investment in the GreenSeeker RT200 system was under $25,000. BF
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