What size disc harrow?

JamesHungwell

New member

Equipment
L4802
Sep 28, 2026
4
0
1
East Texas
I'm running a l4802 and am completely new to both tractors and gardening. I'm looking to manage 1-2 acres of garden, along with some pasture, I'm looking at the king kutter 5.5' with 18-20" discs, I'm in soil that has a good amount of clay, with a decent amount of organic material and some sand. Should I go bigger? Smaller? I've seen posts saying get slightly smaller than the width of the tires, and posts saying go slightly larger, so I'm a bit confused. I've also seen people say get adjustable angle ones, and others not mention it...
 

Captain13

Active member

Equipment
M7040 4WD ROPS, ZD28, Woods (84” box blade, 72” harrow, 48” pallet forks)
Feb 27, 2019
530
173
43
Kathleen, GA
If I remember correctly, the rule of thumb is 6 hp for every foot of disk. So theoretucally, a 48 hp tractor could do a 8 foot harrow. Realistically, I would not do that. That’s assuming a 4wd tractor and, to me, the tractor would be overworked. My land has a lot of clay and my 7040 pulling a 7 foot harrow with the disks angled in is working pretty hard to pull the harrow. I have the adjustable angle disks, front and rear and that significantly adds the the power requirement.

Typically, harrow size is recommended to be no wider than the rear wheel width. That’s what I based my harrow size on. The outside disks on the rear are just outside of my rear wheels so I leave no tire tracks. My rear angle is set to turn the dirt toward the center essentially leaving the plowed ground in a raised bed for planting.
 

JamesHungwell

New member

Equipment
L4802
Sep 28, 2026
4
0
1
East Texas
If I remember correctly, ...
Thanks for that info! so the 5.5' one should be about right then? if memory serves the tractor is at 62" edge of tire to edge of tire. 18" discs are sufficient? (I think they're what it comes with by default)

If going for rows, would I then repeat a pass with a middle buster to get two rows per pass?
 

Motion

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Kubota MX5100HST/FEL
Aug 17, 2020
585
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Mandeville Louisiana
Consider also purchasing a good subsoiler, it'll break up compacted soil and allow the disc to work better. Once you decide which disc to purchase, I'd suggest fabricating a steel frame sized to hold solid concrete blocks if additional weight is desired.
 

BAP

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Lifetime Member

Equipment
2012 Kubota 2920, 60MMM, FEL, BH65 48" Bush Hog, 60"Backblade, B2782B Snowblower
Dec 31, 2012
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New Hampshire
I’m not sure where people are getting the information that you don’t want a disc harrow wider than your tractor. You definitely don’t want it narrower than the tractor. You want your disc harrow wider than your tractor because if you don’t you will leave compacted soil behind, especially in any sort of turns. Also, you don’t need to run the harrow as deep as it will go. 3-6” deep will leave you with a nice planting surface. Many people try to pull the harrow as deep as the blades will allow and then can’t pull it. I farmed for 40 years and we harrowed 1200-1500 acres for planting corn and alfalfa. We had ground that went from prime river bottom, to clay to gravelly hilltop land. Each soil type required adjusting the depth to match the soil type.
 
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JasonW

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Jan 29, 2015
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Al
Definitely get one that has adjustable gangs. I can’t say I have seen one larger than 5’ that has fixed gangs anyway. Get one wider than your tractor.

The more aggressive the angle is the more it cuts and harder it is to pull, so you can get by with a larger disc than normal and have the gangs less aggressive.
You should be fine with a 6’ for your tractor.
Is your tractor gear drive or HST?

Discs need some speed to work well. Around 3-5 MPH depending on soil conditions. Discs are also not a primary tillage tool. They are secondary after plowing. But that depends on what you are trying to do or plant.

I have my offset disc loaded up right now going to plant deer fields.
 
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JamesHungwell

New member

Equipment
L4802
Sep 28, 2026
4
0
1
East Texas
Is your tractor gear drive or HST?
Dealer was trying to sell me on the HST, I didn't like it, so gear drive.
I know it's not commonly use for primary tillage, but I'm looking to build the soil up, and don't want to run a rototiller on it. I'm also just starting out and want to get things like corn and beans and wheat in (for personal consumption, not market) and I don't want to spend $20k on implements
 

JamesHungwell

New member

Equipment
L4802
Sep 28, 2026
4
0
1
East Texas
Consider also purchasing a good subsoiler, it'll break up compacted soil and allow the disc to work better. Once you decide which disc to purchase, I'd suggest fabricating a steel frame sized to hold solid concrete blocks if additional weight is desired.
I was looking at getting one of those spring tine tillers, but the deeper I go, the more heavily clay I get, I kind of just want to build up the top as much as possible.
 

JasonW

Well-known member
Jan 29, 2015
890
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Al
Dealer was trying to sell me on the HST, I didn't like it, so gear drive.
I know it's not commonly use for primary tillage, but I'm looking to build the soil up, and don't want to run a rototiller on it. I'm also just starting out and want to get things like corn and beans and wheat in (for personal consumption, not market) and I don't want to spend $20k on implements
I’m a big fan of used equipment when available. Shouldn’t be too difficult to find a used 6’ or even 7’ disc harrow on marketplace, etc.
I would recommend one with larger blades. Preferably all notched blades. And one that’s heavy duty. Weight can always be added to them, but if you add weight to a flimsy disc to start with, it could easily be damaged.

Most will just stay away from the ones made with angle iron and look for one that is built with square tube. Take that with a grain of salt as I have an Atlas 8.5’ tandem 3pt disc that’s made from angle iron. Although it’s 3” angle 1/2” thick and weighs 1850lbs.

Look into how many pounds are being put into each blade. My Atlas is at 92.5lbs per blade. Whereas my offset disc is 185lbs per blade.