Disc Harrow

Anonymous Poster · Feb 2, 2002

O.K. panel of experts! What is the rule of thumb on disc harrows. I've heard 10hp per plow on a bottom plow, but haven't seen a disc mentioned.
TIA

cowboydoc · Feb 2, 2002

When you say disc harrow are you talking about a disc with harrows behind it? You can pull 20' harrow with probably a 35 hp tractor. Probably need about 20 hp to reasonably pull a 5' harrow over any kind of rough ground. Now if you're talking about a disc the 5' ones they sell I would think a 25 or 30 hp tractor could handle. I've got a jd 4600, 43 hp, and I can pull a 12' hydraulic disc with it with two 5' sections of harrow on it.

Anonymous Poster · Feb 4, 2002

I meant a set of offset discs. I think you answered my question. A 40 horse should pull a 12' set of offset discs then. 45 probably 15'. Am I correct?
Thanks

forestcreature · Feb 4, 2002

a disc harrow has the discs at an angle to the direction of pull [or travel]. generally each side is angled in toward each other.

a disc plow has the discs straight on to the direction of travel, but are leaned over [to turn the dirt].
there are also some discs that aren't leaned over, and are inline too....
the disc plows i have seen were tapered [like a plow where each plowshare was slightly behind the other to one side only.

a harrow is anything that crumbles or smooths the ground. [as opposed to a plow, which is supposed to cut into the ground and turn it over].

the companies like northern, tsc, etc. have descriptions and pics of both disc and drag harrows.

the actual discs come in many designs, but are generally put into four types: smooth, fluted center, fluted edge & center, and notched. they also can be cupped to different degrees.

nothing like a simple description....

i have no idea about how much hp would be needed per width since soil type would have a big impact on that.

i would ask an ag dealer [as opposed to a suburban] dealer in you area since he would be aware of local soil types and experiences.

Anonymous Poster · Feb 4, 2002

Thanks for the "condensed" explanation! /w3tcompact/icons/smile.gif

Chris99320 · Feb 4, 2002

I just disked up my future pasture. I have a 5' 3pt offset disk (FORD 200A) and a Kubota L185 (<20hp) My soil is mostly clay.
The Kubota pulls it with no problem even in high range. But..... The small disks really don't do a great job at breaking up the soil. The disk I have is built pretty stout but I still had to pile on quite a few cement blocks to weight it done enough to penetrate the soil. And I had to wait until my clay soil was damp. It took about 4 passes at different angles across the field to get it broken up. But the field hadn't been touched in several years.
Personally I am thinking about selling the disk and getting a rototiller instead.

cowboydoc · Feb 4, 2002

I don't think you could pull a 15' disc. A 12' one is about the highest I think you could go with these compacts. Now I haven't tryed but I don't think you could pull one.

looch · Feb 4, 2002

My B7500 owner's manual (or sales brochure - can't remember and it's not with me right now) lists available implements and recommended sizes. The disc harrow they list is only 4'. I imagine it would be able to pull the more common 5' size, though. One of the disc harrow manufacturers lists how many hp per disk is required for their particular model - Buhler/Farm King I believe.

patton · Feb 4, 2002

I have a 6-1/2' Heavy Duty disk (~1200 lbs). With a 33 pto HP(5 hp/ft), I run out of power once the soil gets broken up, with a 45 hp 5200(6.5 hp/ft), I run out of traction (2WD). In near worse case conditions (AR Gumbo mud/drained rice field), I've seen a 40' disk really load down a ~400 hp tractor (10 hp /ft)

Remember a disk harrow must move at a certain speed to do a good job, you can't subsitute torque for power, as owners of compact tractors typically do.

Light weight harrows require much less hp, but only because they do less work. You can also decrease the tilt of the gangs, which makes them less agressive (again reducing tillage depth.)

If you can't pull a real disk, look at a plow/field cultivator followed by a chain harrow (chain link fence fabric), or a rototiller, or something similar.

Pat