Weed and weather maps trigger farm decision-making
Written By: Larry Reichenberger
Gary, Daryl, and Wayne Wagner have identified over 40 factors that impact yields on their farm near Crookston, Minnesota.
“About 50% of that yield impact is related to the environment, so we can do little about that,” says Gary. “But we can have an impact on another dozen yield factors. By managing those factors, we can think we can generate enough combined benefits to pay for precision farming equipment in a single year.”
Four years of yield mapping have convinced them precision farming pays - and that variable-rate chemical application is one factor that will help balance the bottom line. In 1996 they varied chemical application rates to match spatial weed pattern.
Maps below show wild oat pressure captured while combining in 1995, using the field marking feature of their Ag Leader yield monitor - compared to mapping emerged weed patch the next spring from Kawasaki Mule. They also use the Mule with a 33-foot boom for variable-rate spot-spraying according to geo-referenced maps.
They found little difference in the maps- but they were surprised by the size of the will at problem they faced. “Roughly 50 acres of this 160-acre field contained enough wild oats to justify treatment,” report Gary. They used a 5-ounce rate on part of the field, and a 3-ounce rate for foxtail on the balance.
Gossip has long made farmers aware that rainfall varies from neighbor to neighbor. Now, technology shows how much it varies even within the same field - and the impact on crop yields.
The Wagner farm has 28 digital rain gauges at 1/2-mile intervals. “We’ve been amazed by the variation,” says Gary. Map at the left shows rainfall recorded from August through October 1996 across a 640-acre section. Total rain fall ranged from 1.96 to 4.24 inches. This season, rainfall amounts from June 1 until July 10, 1997 have varied by more than 3 inches. Next step: compare yield maps and crop records to track impact of the variations.