When Jim and Mark Koenigs switched to no-till soybeans and narrow-row corn in the late '90s, the brothers found the crops left more residue than their field cultivator could get through. So they pulled out their old tandem disc harrow to cut up and incorporate the extra stalks and stems.
“Our tillage practices have evolved,” says Jim Koenigs from his farm office in McIntire, IA. “But there still seems to be a need for a disc harrow — even though our use of it has changed.”
The Koenigs previously used their disc harrow to prepare the seedbed for planting. Today they use it more to manage residue. They use it in the fall on ground left with a heavy mat of soybean stems and leaves that will be planted to 20-in. corn. They also use it in cornfields after harvest for leveling ruts from grain carts but where they don't think deep tillage is justified.
In some cases, they use it in the spring before planting no-till soybeans to warm the soil so they can plant earlier for higher yields.
“If the ground is dry enough and it is getting later in planting season, we'll use the disc harrow ahead of our no-till drill,” Jim explains. “We have noticed quicker emergence, faster early growth, and a higher percentage of emerged seed on the fields we are able to disk. And it also kills that early flush of weeds.”
Their new uses of this conventional tillage tool have prompted them to buy a brand-new disc harrow — a 46-ft. double-fold from Krause Corporation. And they are not the only farmers buying.
Major disc harrow manufacturers, including Krause, Sunflower, John Deere, Case IH and New Holland, all report a 5 to 7% increase in sales from last year to date. That's following a 20-year drop caused by the boom of no-till in the late '80s and early '90s and the declining number of farmer-buyers.
“Disc harrow sales have remained steady or higher than field cultivator sales, which I think would surprise many people,” says David Benson, product marketing manager with Krause. “It's just such a versatile tool.”
New use for old tool
Tandem disc harrows, also known as “finishing discs” or “double-offset discs,” are not new. They were invented back in the 1800s to break up clods left by moldboard plows. But what is new is how they are being used.
Originally designed as a seedbed preparation tool, they are now used to manage residue from corn, beans and wheat. Higher plant populations, no-till soybeans, and genetically modified crops with tougher stalks and stems that don't deteriorate as fast over winter as conventional hybrids do are all to blame for increased amounts of residue.
Farmers like the Koenigs are finding that a disc harrow can be their best defense. “There are customers out there saying, ‘There was way too much residue last year, and I don't want to deal with it again this spring,’” says Matt Weinheimer, marketing manager for tillage, John Deere Des Moines Works. “So they want to hit it with a disc before they come in and cultivate.”
“Discs used for crop residue management really have no direct alternatives,” says Bill Preller, global platform manager, Case IH Soil Management Equipment. “Other implements may size residue but not mix it with the soil, and some mix without sizing.”
Disc harrows can do both because of their design. Rows of concave discs arranged in an X pattern run at an angle to both slice and mix material without plugging like a shank-type tool can. “The front rows throw soil outward and the back rows throw soil inward, leaving an even layer of mulch to meet requirements of the conservation-type farmer,” says Gerald Meier, vice president and general manager with Sunflower Manufacturing.
It has other uses as well. The same disc can be used to level ruts in the field left by trucks and grain carts, incorporate surface-applied manure, or control weeds and promote soil warm-up in the spring before planting. “If it is getting into late spring and weed growth is out there, the best device mechanically to take care of it is a disc, especially with the weight and cutting capacity of today's disc,” Meier adds.
Consider the downsides
On the downside, they take more horsepower to pull per foot of width compared to a field cultivator, according to Paul Hurtis, global product manager, New Holland Soil Management Equipment.
Requirements vary by the size of the disc but range from 180 to 450 hp from 10.5- to 38-ft.-wide discs. And some designs may ridge at higher operating speeds.
Ken Ferrie, agronomist with Crop Tech Consulting in north-central Illinois, cautions that, because the disc works the surface of the soil, it could cause a shallow horizontal layer of compacted soil 1 to 3 in. down where the disc runs.
For that reason, Ferrie advises that a farmer run the disc shallow enough to just chop the residue without tilling. Or, if the disc is used for tillage, it should be used in rotation with deeper tillage tools to break up that layer.
Those drawbacks said, the tandem disc harrow is an effective way to handle the increased residue in many farm fields today. If you have been out of the market for one for awhile, you'll notice several improvements over the model you may have parked on the back forty.
New and improved models
First, the new ones are bigger and can run faster than before to cover more acres. “Recent design innovations now allow for tandem discs that can operate up to at least 7 mph with very level output, which now allows them to rival other tools in productivity per foot of width,” says Case IH's Preller.
They are also built heavier, with larger gang shafts and bearings to penetrate and cut the ground better and keep up with the newer, higher-horsepower tractors, according to Sunflower's Meier.
Another improvement is that they are more precise. New discs have depth-control wheels that control how deep the discs run, and the old standard duals have been replaced with walking tandem wheels to keep the machine level with less bouncing in the fields. Gang angles are now preset versus variable to keep depth consistent and ensure the discs pull straight and provide the optimum cutting and penetration.
Finally, they are easier to use and maintain, with single-point depth control and fewer lube points, Meier adds.
To help illustrate these improvements, we asked some of the major manufacturers to show us their lineups. And to help you comparison shop, we asked them to share key features.
ST440 Seedbed Disc Harrow
Designed for farms of all sizes needing a seedbed preparation disc.
Tandem design, crimp center blades, “slim-center” nodular iron spools for better residue flow, and C-spring-cushioned gang mounts.
Choose between 7.5-in. blade spacing with 20-in.-dia. blades or 9-in. spacing with 22-in.-dia. blades.
19 to 34 ft. wide.
Suggested list price: $20,000 to $41,000.
ST460 Heavy-Duty Disc Harrow
Designed for mid-size to larger operations needing a heavy-duty, all-purpose disc capable of both residue management in the toughest conditions and seedbed preparation.
Same features as those on the ST440, plus shallow concavity front disc blades for deep soil penetration with less down pressure.
24-in.-dia. blades in 9-in. spacing
5- to 34-ft. working width.
Suggested list price: $26,000 to $44,000.
Should you buy?
The following conditions may indicate the need for a tandem disc harrow:
If your fields have more crop residue than other tillage tools can handle.
If you need a tool that can both cut and mix material with the soil.
If you want a tool capable of both residue management and seedbed preparation.
If your farm is in an area of the country where rocks are a problem and you want to use the tool for primary tillage without the risk of bringing up rocks.
If your farm is in an area where you pasture crop residue and need to penetrate tough ground compacted by livestock.
If you need a mechanical way to kill weeds prior to planting.
If you need to incorporate surface-applied manure into the top 3 to 6 in. of soil.
If you need a tillage tool that can be used in both the spring and the fall.
Buyer's spec sheet
12 points to compare before buying a tandem disc harrow
How many pounds per blade or pounds per foot will you need to cut through residue?
- Weight per blade:
Contributing factor to down pressure, which is needed to slice through residue and tough soil conditions.
- Blade spacing:
Important for residue flow, ground penetration and leveling ability. Ranges from 7.5 to 11 in., with 9 in. most common.
- Blade size:
Matt Weinheimer, marketing manager for tillage, John Deere Des Moines Works, recommends ¼-in.-thick × 24-in.-dia. blades for heavy clay soils of the Midwest. “The thicker and larger blades create a larger cutting surface, which provides better rock protection and residue flow,” he says. “The exception is the Great Plains wheat country, where it is better to go with a .197-in. blade and a narrower 22-in. diameter because all you are looking for is chopping up wheat stubble and penetrating hard ground conditions in sandy clay loam soils.”
- Gang angle:
The higher the degree, the more aggressive cutting and mixing, with 20° on the front gang and 18° on the rear gang being the most common.
- Horsepower requirements:
Ask, What width do I need to fully optimize all my horsepower? Weinheimer says. The typical range required is 180 to 450 hp, but be sure to visit your nearest dealer to determine tillage width, horsepower per foot, and draft type.
What kind of harrow attachment is available?
- Rock capability:
Does the disc have flexible C-spring standards and heavy-duty spools that absorb shock from rocks?
- Number of sections:
If your farm has rolling or rocky terrain, ask, Will this disc be flexible enough to follow ground contours?
- Leveling ability:
“Look for one that does a level job across the entire width, leaving no ridges or furrows,” says Gerald Meier, vice president and general manager of Sunflower.
What kind of service will the dealer and company deliver?
- Maintenance requirements:
Look for one that reduces maintenance requirements and time spent greasing.
7300 series discs are Class 1 seedbed finishing in the 7¾-in. blade spacing and Class 2 all-purpose in the 9⅛-in. blade spacing.
High-speed, low-draft design for conservation disking or residue management on corn and soybean farms. Sizes range from 18 to 34 ft. Suggested list price ranges from $19,654 to $29,527, with the price of Rock-Flex models slightly higher.
All-purpose discs (Class 2)
Versatile enough for primary tillage in the High Plains or Corn Belt states with depth control for secondary tillage or seedbed finishing. Rock-Flex bearing arms protect disc gangs from obstacle damage, and walking tandems provide smooth disking at higher speeds.
8- or 9⅛-in. blade spacing and 22- or 24-in.-dia. blades.
7400 series sizes from 18 to 27 ft. Suggested list price: $22,930 to $30,512.
4995 series sizes from 28 to 36 ft. Suggested list price: $30,589 to $40,018.
7400-46 series in sizes from 41 to 46 ft. Features a double-fold system for easy transport. Suggested list price: $46,804 to $50,569.
2490 series (Class 3) primary tillage discs
Recommended for extreme residue or hard soil conditions. High weight per blade provides deep penetration and residue-cutting ability. 2490 series discs cover and incorporate a higher percentage of crop residue than all-purpose class discs do.
Choice of 24- or 26-in. blades.
Sizes range from 23 to 36 ft.
Suggested list price: $32,856 to $47,458.
3850 Rigid and Folding Seedbed Disc
Designed for smaller and more diversified operations; 10- to 21-ft. working width.
RMX340 Flex-Wing Seedbed Disc
Designed for the mid-size to larger operation needing a seedbed or light residue management disc; 19- to 34-ft. working width.
RMX370 Flex-Wing All-Purpose Disc
Designed for the mid-size to larger operation needing an all-purpose, residue management and seedbed preparation disc. Shallow concavity front blades; 25- to 34-ft. working width.
Both the RMX340 and RMX370 are true tandem discs with crimp center blades and coil tine or spike harrows that mount directly to the mainframe.
RMX340 — 20-in. blades on 7.5-in. spacing, or 22-in. blades on 9-in. spacing
RMX370 — 24-in. blades on 9-in. spacing
596 Flex-Wing Residue Management Disc
Heavy-duty disc for residue management in the toughest conditions. Blade spacing and sizes available: 26- or 28-in. blades on 10.5-in. spacing. 22- to 31-ft. working width.
Suggested list prices for all Case IH discs: less than $10,000 to about $40,000, depending on model, features and size. Contact Case Corp., Dept. FIN, 700 State St., Racine, WI 53404, 262/636-6011, visit www.caseih.com or www.freeproductinfo.net/fin, or circle 224.
637 Rock Disc
Recommended for Midwest farms with medium to heavy draft applications.
C-spring disc gangs, ¼-in.-thick disc blades, and heavy-duty 5½-in. spools with ¼-in.-thick walls and a 1¼-in. gang bolt.
24-in.-dia. blades and 9-in. blade spacing in front and rear. Optional 9-in. front and 11-in. rear blade spacing.
12-ft. 2-in. to 37-ft. 10-in. working width.
Suggested list price: $11,500 to $43,000.
637 Wheatland Disc
Recommended for Wheat Belt areas where residue cutting and blade penetration are needed.
C-spring disc gangs with .177- or .197-in.-thick disc blades, and heavy-duty 5½-in. spools with ¼-in.-thick walls and a 1¼-in. gang bolt.
22- × .177-in. or 24- × .197-in. blades on 9-in. blade spacing in front and rear.
12-ft. 2-in. to 37-ft. 10-in. working widths.
Suggested list price: $11,000 to $42,000.
637 Regular Disc
Recommended for areas with lighter soils where rock protection is not needed.
Rigid disc gangs are available with 22- or 24-in.-dia. blades on 7¼- or 9-in. blade spacing and blade thickness ranging from .177 to .256 in. (¼-in.-thick blade).
1⅛-in. gang bolt is used with 4½-in. spools on non-folding models; 5½-in. spools are used on folding models.
11-ft. 5-in. to 37-ft. 10-in. working widths.
Suggested list price: $9,100 to $38,500.
650 Flex-Fold Disc
Recommended for heavy draft applications only.
Higher gang angle, 22° front and 20° rear.
24- and 26-in.-dia. blades are available in 9-in. spacing, 11-in. spacing, and 9 in. in front and 11 in. in back.
Working width: 23 ft. 9 in. to 32 ft. 4 in.
Suggested list price: $27,800 to $35,500.
John Deere's hydraulic wing control option
Available on 637 and 650 folding discs only (except for 637 disc sizes 35 ft. and 37 ft. 10 in.).
1000 series discs are designed for all grain-producing regions in the U.S. with models to fit 75 to 500 hp. Available in working widths from 10 to 45 ft.; 22-, 24- and 26-in.-dia. blades, and 7½- to 8¾-in. blade spacings. Includes:
1300 series offset discs in two- and three-section models from 10 to 20 ft.
1200 series discs in rigid and three-section models from 10 to 32 ft.
1434 series discs in three-section models from 18 to 36 ft.
1444/1544 series discs in four-section models from 30 to 45 ft., which flex side to side and front to rear to provide flexibility for rolling or terraced ground or rocky conditions.
Features of 1000 series discs:
Standard gauge wheels on front of wings.
Swivel-type versus fixed rigid gauge wheel.
Ultrahigh-molecular-weight polyethylene, a high polymer plastic, used in high-wear areas.
Three-year warranty on entire product, including frames, bearings and hydraulics.
Hydraulic self-leveling option.
C-flex hangers and gauge wheels are standard equipment on all discs.
Guaranteed to level.
Flexible models fold up for transport.
Suggested list price: 18-ft. 1233 model: $22,805; 32-ft. 1233 model: $33,610.