Small Farmer's Journal

or Subscribe
Disc Harrow Requirements

Disc Harrow Requirements

reprinted from Farm Practices by Allis Chalmers Co.

We especially emphasize here the expected requirements of a disc harrow which should not be overlooked before taking a harrow to the field. One of the most important requirements is disc blade concavity, that is, correct concavity. Further along we set forth the purposes of disc concavity. We feel it is important enough to devote the extra time and words in a discussion of the subject, because seldom is disc concavity talked about, and very few know that there is difference enough to cause good and bad work. Almost everyone has the idea that discs are all alike, that curvatures and sizes are the same, and if one style disc does good work, that any other style should do likewise. Proper disc angling is also a needed requirement in order to get even depth of all discs for deep or shallow work, and to get maximum pulverization in all soils. Here are some of the requirements:

  • Frame — Correct design very necessary; best materials should be used.
  • Hitch — Must hold gangs securely; must also get quick depth.
  • Gang Bolts — Should be large; durable; self-locking.
  • Bearings & Bushings — Need to be close fitting and made of best quality material.
  • Spacing Spools — Should be milled to fit the disc centers.
  • Scrapers — To be easy on disc blades.
  • Angling Controls — Quick and easy control is essential.
  • Gang Angling — Must be correct for all depths and speeds.
  • Follow Contours — Should be flexible as well as rigid.
  • Discs — Correct concavity; properly treated for long life; extra thickness.
  • Center Control — Should fill dead furrows and level back furrows.
  • Compacting Soil — Correct angle and concavity will do so.
  • Speed — Must be designed for faster tractor travel.

Disc Harrow Requirements

Discs today last longer than discs of 20 years ago and testing is done scientifically. Laboratory tests are made first, and then they are put in all field soils to determine their lasting qualities. Disc blades are heat-treated for long life, and seldom, if at all, will they chip while working. The angling of the gangs must conform to the disc concavity for holding penetration at any depth, and the disc concavity must also match speed at which disc harrows can travel and do quality work.

At the extreme angle the discs cut a clean furrow with no drag on the backside and with no chattering or jumping — that is, they should do so. If not, then there is either too much or too little angling. The concavity also gives the correct curvature in the ground for steady running when set with the least amount of angle. When discs notch the small furrows in washboard fashion working at the minimum angle, it is because the concavity does not follow through with the correct slant against the ground to take a cutting bite. It’s like trying to whittle with a pocketknife set too straight against the wood. With correct concavity, at all angles, and the disc edges set at a pocket knife pitch against the ground for clean cutting, smooth shavings result without jumping and notching the furrows. The correct concavity and angling eliminates the deep furrows.

Disc Harrow Requirements

The disc harrow, like the plow, must have a range of varied depths, or it would be of little value. The disc blade is to the harrow what the plow bottom is to the moldboard plow — it is the business or working end of the tool. Frames, bolts, spools, hitch and proper weight are needed and they do their share to cause good cutting. But the actual cutting, lifting and turning of the dirt is effected by the discs, and to do this work the way the users, soils and conditions require it done, demands discs that have correct concavity, made out of the best material, and then properly heat-treated for a lasting and uninterrupted life.

The subject of disc concavity — disc curvature in other words — seems to be misunderstood, therefore, it is our purpose to clarify the reasons for the disc concavity so as to set everyone right. But we also want to show that there is a difference in disc concavities, and we also want to show what happens when the different shapes are used.

The original harrow was merely a log rolled along to break clods, level surfaces and pack the seedbed to eliminate the air spaces between the turned furrow slice and the furrow sole. It did well as a surface packer and leveler, but it failed to reach down far enough, therefore, its use was limited. Very shortly, from experience in packing dirt around posts, foundations, planting trees and shrubbery by using the spade, discs were conceived — strung on a pole and rolled along — in order to reach down for packing the loose soil nearer the furrow bottom.

Tamping with the cutting edge of a spade in loose and lumpy dirt around posts or newly planted trees, packs to the depth of the hole by pulverizing the clods and compacting the pulverized dirt around them in order to eliminate air pockets, and avoids any great amount of settling later on when the dirt takes up moisture. The disc blade, likewise in a loose and lumpy seed bed, pulverizes the clods and compacts the loosened dirt down deep as it rolls along and, therefore, overcomes the dirt settling in spots over the field to effect water holes where clods were not pulverized — a condition often seen when the disc harrow has not been used.

The disc harrow is also used for seeding by mounting a hopper over each disc gang. It packs, levels, crushes clods, and drops the seed in the disc trenches. While the disc harrow proved the most versatile tool on the farm, it still presented problems of clogging, wearing quickly, disc breakage, buckling and heavy draft. The disc blades were responsible for most of these ills, consequently, much research followed to get proper disc curvature so as to have the best cutting curve for penetration and to lighten the draft. The proper concavity solved these problems, and that’s why correct concavity discs really dig deep when required, pull light and last so much longer.

A flat disc blade will cut just as deep as a concave blade if set at a cutting angle, the same as you would tilt a knife blade to cut a clean shaving. The trouble with the flat disc is: no control of the dirt, which merely slides on past to one side — all trash exposed — and more power is required to pull it. The flat disc will also leave deep furrows under the loosened surface and it is more sensitive to varying ground pressures. In hard ground it is jumpy, also true of a disc with too shallow concavity; and in loose ground, like the shallow discs, it digs too deep and pulls hard.

or Subscribe to read the rest of this article.

SmallFarmersJournal.com is a live, ever-changing subscription website. To gain access to all the content on this site, subscribe for just $5 per month. If you are not completely satisfied, cancel at any time. Here at your own convenience you can access past articles from Small Farmer's Journal's first forty years and all of the brand new content of new issues. You will also find posts of complete equipment manuals, a wide assortment of valuable ads, a vibrant events calendar, and up to the minute small farm news bulletins. The site features weather forecasts for your own area, moon phase calendaring for farm decisions, recipes, and loads of miscellaneous information.

Spotlight On: People

Fjordworks A History of Wrecks Part 2

Fjordworks: A History of Wrecks Part 2

It is always fascinating and at times a little disconcerting to watch how seamlessly the macro-economics of trying to make a living as a farmer in such an out-of-balance society can morph us into shapes we never would have dreamed of when we were getting started. This year we will be putting in a refrigerated walk-in cooler which will allow us to put up more storage-share vegetables.

To Market, To Market, To Buy A Fat Pig

Within so-called alternative agriculture circles there are turf wars abrew

Biodynamic Meeting at Ruby and Amber’s Organic Farm

Biodynamic Meeting at Ruby and Amber’s Organic Farm

by:
from issue:

One weekend I attended a Biodynamic meeting at Ruby and Amber’s Organic Farm in Dorena, Oregon, in the Row River Valley, just east of Cottage Grove. I always enjoy seeing other food growing operations, as this is such an infinitely broad subject, there is always much to learn from others’ experiences. At this farm, draft horses are used for much of the work.

Honoring Our Teachers

Honoring Our Teachers

by:
from issue:

I believe that there exist many great practicing teachers, some of who deliberately set out to become one and others who may have never graduated from college but are none-the-less excellent and capable teachers. I would hazard a guess that many readers of Small Farmer’s Journal know more than one teacher who falls within this latter category. My grandfather, and artist and author Eric Sloane, were two such teachers.

The Way To The Farm

Lise Hubbe stops mid-furrow at plowing demonstration for Evergreen State College students. She explains that the plow was going too deep…

Central Oregon Food and Farms

Central Oregon Food and Farms

Who is growing food in the high desert? How can you find it? And how can you contribute to creating a vibrant local food community in Central Oregon? Find out here! By consuming more Central Oregon grown food we keep money in our region, support local businesses, and have delicious, fresh food to eat.

Icelandic Sheep

Icelandic Sheep

by:
from issue:

I came to sheep farming from a background in the arts – with a passion for spinning and weaving. When we were able to leave our house in town to buy our small farm, a former dairy operation, I had no idea that the desire to have a couple of fiber animals would turn into full time shepherding. I had discovered Icelandic sheep, and was completely enamored of their beauty, their hardiness and their intelligence.

Congo Farm Project

Congo Farm Project

by:
from issue:

I was at day one, standing outside an old burnt-out Belgian plantation house, donated to us by the progressive young chief of the village of Luvungi. My Congolese friend and I had told him that we would need to hire some workers to help clear the land around the compound, and to put a new roof on the building. I thought we should be able to attract at least 20 workers. Then, I looked out to see a crowd of about 800 eager villagers, each one with their own hoe.

B. Adroit's Profiles in Passion: Herscel Gouda

B. Adroit’s Profiles in Passion: Herscel Gouda

Excerpt: Um, ya, you’re just gonna have to read this one.

Farmrun A Reverence for Excellence

A Reverence for Excellence

A portrait of Maple Rock Farm and Hogstone’s Wood Oven, a unique farm and restaurant on Orcas Island where the farmers are the chefs, A Reverence for Excellence strives to be an honest portrayal of the patience, toil, conviction and faith required of an agrarian livelihood.

Ripening

Poetry Corner: What A Boy Lies Awake Wondering

This is a poem from Paul Hunter’s book Ripening.

Birth of a Farm

Birth of a Farm

by:
from issue:

“Isn’t it nice?” I offer to my supper companions, “to see our beautiful horses right while we’re eating? I feel like I’m on a Kentucky horse farm, with rolling bluegrass vistas.” I sweep my arm dramatically towards the view, the rigged up electric fence, the lawn straggling down to the pond, the three horses, one of whom is relieving herself at the moment. “Oh, huh,” he answers. “I was thinking it was more like a cheesy bed and breakfast.”

Fjord Horses at Work in the Green Mountains of Vermont

Fjord Horses at Work in the Green Mountains of Vermont

We own a 40 jersey cow herd and sell most of their milk to Cobb Hill Cheese, who makes farmstead cheeses. We have a four-acre market garden, which we cultivate with our team of Fjord horses and which supplies produce to a CSA program, farm stand and whole sale markets. Other members of the community add to the diversity of our farm by raising hay, sheep, chickens, pigs, bees, and berries, and tending the forest and the maple sugar-bush.

NYFC Bootstrap Videos The Golden Yoke

NYFC Bootstrap Videos: The Golden Yoke

I couldn’t have been happier to collaborate with The National Young Farmers Coaltion again when they called up about being involved in their Bootstrap Blog Series. In 2013, all of their bloggers were young and beginning lady dairy farmers, and they invited us on board to consult and collaborate in the production of videos of each farmer contributor to the blog series.

It Is Who We Are

It Is Who We Are

by:
from issue:

It is NOT a small world, it is a BIG world, as wide and various as you can possibly imagine. We are not alone. When we feel ourselves shut down, crowded by worry and a sense of failure, it would serve us well to remember Bulldog’s admonition, “Boss, never give up, no matter what, never give up.” Anyway, how could we? Who would put up the hay? Who would unharness the team? Who would milk the cows? Who would wax the cheese? Who would feed those woolly pigs? It’s got to be us, after all it is who we are.

NYFC Bootstrap Videos Clover Mead Farm

NYFC Bootstrap Videos: Clover Mead Farm

I couldn’t have been happier to collaborate with The National Young Farmers Coaltion again when they called up about being involved in their Bootstrap Blog Series. In 2013, all of their bloggers were young and beginning lady dairy farmers, and they invited us on board to consult and collaborate in the production of videos of each farmer contributor to the blog series.

The Farmer and the Horse

The Farmer & The Horse

In New Jersey — land of The Sopranos, Jersey Shore, and the Turnpike — farmland is more expensive than anywhere else. It’s not an easy place to try to start a career as a farmer. But for a new generation of farmers inspired by sustainability, everything seems possible. Even a farm powered by draft horses.

Journal Guide