Can a conventional farmer achieve effective weed control using lower
levels of herbicide than recommended by the manufacturer? Dale Katterhagen,
a dairy farmer in Todd County, and Del Glanzer, an Alexandria based crop
consultant, have developed a method for using reduced levels of Roundup
in preparing old alfalfa fields for corn planting.
Katterhagen farms about 355 acres, raising steers and milking about
50 cows. He annually converts around 50 acres of three- to five-year-old
alfalfa to corn, an amount typical of many other dairy farms in the area.
By combining spray-grade ammonium sulfate with Roundup, Katterhagen achieves
a more efficient uptake of the herbicide by the weeds. This approach
allows Katterhagen to use less Roundup and reduce his overall cost.
Katterhagen and Glanzer emphasize that farmers must combine understanding
of weeds and herbicides with planning to obtain efficient weed control.
The farmer should first identify the weeds in the field and decide which
ones to target. The farmer should then become familiar with the life
cycle of the target species. By selecting herbicides most appropriate
for the target weeds and applying them at the most vulnerable points in
the weeds' life cycles, more effective weed control can be achieved with
lower levels of herbicide. For example, it is best to treat weeds
while they are still small. Strategies to improve herbicide uptake,
such as combining the herbicide with an appropriate fertilizer, can further
enhance the effectiveness of an application. The farmer then can
adjust future plans based on the results obtained.
By experimenting with his approach over a number of years, Katterhagen
has reduced his herbicide costs between $6 and $12 per acre. Factors
such as timing affect the effectiveness of an application and consequently
the total cost per acre. For the Pesticide
Reduction Options project, Katterhagen and Glanzer demonstrated side by
side comparisons of applications of Roundup at a rate recommended by the
manufacturer and at a lower rate. Assuming an average $8 per acre
savings, Katterhagen estimates an annual farm savings of $400, using his
approach.
Katterhagen also emphasizes the importance of
carefully calibrating the sprayer. At one of the field days on Katterhagen's
farm, Richard Hunt conducted a sprayer clinic. Hunt is a representative
for Hardi, a Swedish company and reputedly the world's largest manufacturer
of agricultural sprayers. Hunt addressed safety issues and discussed
the importance of accuracy of sprayer calibration. He described
qualities to look for in nozzles and how to choose a height for the sprayer's
boom. He also discussed the potential for reducing herbicide rate
through the use of air assisted sprayers.
Sources
Frazeur, Andrea, (1997). "Spreading the Sustainable Story," AURI
AG Innovation News, July 1997.
"Sprayer Clinic," Leader, pp. 2A & 13A, 6 August 1997.
