Question about plows

Some folks say it doesn't matter how wide a bottom is they all dig about the same depth. Others say the wider the plow is the deeper it digs.
I don't have any experience beyond 3-16s but it seemed like there wasn't much difference in depth between that and the 2-14s I've had. They all seemed to dig about 8" deep. The 1-14" I had probably dug the deepest. I could really bury that thing - probably 10" at least.
But what about big plows that are 20" and over?
Is depth a function of width on those? Is there a formula or rule of thumb on width vs depth of cut?
Thanks to any and all.

Your supposed to plow half the width of the shear. 16 inch shear 8 inches deep as example. You can plow deeper but then the plow does not turn the soil over as well. You can really tell it in sod ground. If you plow too deep the sod is stood on edge rather than turned over. Guy got to plowing as deep as they could around here and then complained when their plowing job had weed/grass/alfalfa growing up through the furrows.

I never really understood that,
guess that is why over the years I have always said the 3x12" MF62 plows I have do a poor job, even though I have installed new points and new coulter blades.

I was always trying to plow deeper than 6" and the plows would not turn over the dirt very well, I only have a TO-35 and it does not have the power to pull the plows faster than in the low third gear.

will check that rule out, when I break my gardens this spring and keep the depth at no more than 6". old tractor would have been more suited to 2x14" plows, guess Ferguson back in the day was trying to make a big dog out of a little dog.

JDSeller has it mostly correct, 5" for 10", 6" for 12", 7" for 14", 8" for 16" and so on from the manufacures but then on some makes MF that I know of they had a deep tillage bottom in at least the 14" size and you could not do a good job at normal wanted depth. Found out about those no good bottoms when tried to buy repair parts for them and had a time finding any.

That is exactly what happens when I get into an area of deep top soil adjacent to small marsh or wet land whereas it too is soft from moisture, often times some thick abrasive kinds of grass. There are a few areas along the field perimeters like that here. When the plow hits these conditions, it wants to suck in further, and I don't believe my draft control was working, so I left it in position, did it by hand. Most times I respond to it and it keeps from going too deep, if not, it may stop the tractor, lose traction and most certainly will stand the sod on end instead of flipping over. Its one of the reasons I use my single bottom as 2 is more than the tractor would handle, each of my food plots has or had conditions like that. It allows me to minimize just what you describe and the last time I did it, I got a full stand in the spring, nothing came back because it was not plowed under. I was trying to reclaim one rectangular area of an overgrown field that had not seen tillage or anything since the late 80's, but the ruts were still there. The rest of the patch plowed nicely, but when I got in there with the 2 bottom, and mind you with the tractor I was using, it may not have been ideal, it mostly did that, stood on end. But not all was lost, though whatever that grass was initially, came back, but I was able to run the disc through there, it eliminated the ruts and repaired the drainage, it was miserable to mow that piece, I've got one more like that, old ruts in a low spot but it will need the dozer to grade the surface of the trapped water. Along the path, the log skidder heaved the sides and stopped the natural drainage, then a thick patch of buck thorn came up as it was never corrected.

As said the rule of thumb can be broken. Here's a shot of my 2x14 IH #39 two-way doing a good job at nearly a foot deep. The surface was pretty clean so I don't know how good of a job it would have been doing with a lot of trash.

The general Rule is that you should not plow any deeper than 1/2 the cutting Width (generally).

BUT, there is no set rule that you can't plow shallower..!

Those 20" and wider plows are wider to give even more Trash clearance AND cover more Acres...

Ron.

If I was plowing sod under, 8-10 deep with 16" bottoms worked pretty well. Once I plowed deeper the sod didn't turn over properly. Much less than 8 inches didn't bury the sod very well. On stubble I could plow as deep as 12 inches and as shallow as 4 inches with good results.

If you have ever looked at the back bottom edge of a moldboard and it is razor sharp that is a sign that it has been run deeper than designed, run at design depth it will not develope that razor edge. Most plows you will find that razor edge on as they have been run deeper than the design is made for.

3x12 Fergy plow was a step up from original 2x12 Ford 9N plows. You found out that deeper than 6 inches was not a good job- got to remember that Pre WW2 a lot of the old horse equipment was still used and 10 inch shares were still around, 12 was a recent standard and a 14 or 16 incher was the 'Big' plow that needed a 4 horse hitch with big horses instead of a 2 mule hitch. 8 inch shares on 'Scots' plows in 3 or 4 shares were used on wheat and small grain fields that didn't need a deep seed bed and might in some case be a field of thin top soil, about the same depth subsoil and then a rock base- like Scotland oats field or the chalk downs of England. 3x12 at 5 to 6 inch should give a complete turnover and 1/2 finished seed bed good for most crops, garden use. You want a deep tillage for a Midwest deep topsoil- get the single 16 inch plow or a single point subsoiler to break hardpan. Dry land corn would want a 2 to 3 inch trench from planter/drill with another 3 to 4 inch worked soil for the seed root- that is where the 14 and 16 inch moldboards would be needed especially if working up sodded pasture. Oats, Barley, peas, wheat would want a 1 inch seeding or top broadcast with another 3 or so inches root grow depth- multiple 10 or 12 inch shares would give enough depth at 1/2 width of share and extra share would do more acres- 3x12 compared to 2x12 on tractor with a 'better than 2 mule hitch' sulky plow time. RN

Brendon-KS: If you look close at your picture you can see where your NOT turning the soil over. You are just moving it side ways. Since most crops today are grown using some type of herbicide covering up the old weeds/grass/crop residue is not as important as when you where plowing to bury last years seeds. IF you took that same plow into sod ground and plowed that deep you would see where it would just stand the sod strip on its edge. It would NOT be turn comp-lately over.

When we used to plow under old stands of prairie grass with tremendous root masses the soil would be in one long strip. It would be a solid strip of soil and roots. IF you ran the correct depth and speed the plows would turn it over 180 degrees with a smooth top layer of the bottom of the cut soil. The best plow I owned or used to do this with was an Oliver 565. It would lay it over smooth and with speed. My JD 1250 plows with the high speed moldboards would hump the strips in places if you did not drive pretty slow. The JD 1250s did a nice job at higher speeds in crop ground with heavy trash.

Here is a poor job of plowing sod. He need to set his plows better for furrow width but you can see where he is plowing so deep the sod is just quarter turned not fully flipped.

<image src="http://forums.yesterdaystractors.com/photos/mvphoto18254.jpg"/>

In this older picture you can see where this plow is set to where the sod is completely flipped upside down with the grass completely upside down. Also this plow is leaving a very smooth finished job. That takes setting the plow correctly and driving the correct speed. On most plows changing the ground speed will effect the quality of the plowing job.

<image src="http://forums.yesterdaystractors.com/photos/mvphoto18255.jpg"/>


Here in the Midwest as tractors got to be higher in horse power and guys could pull plows at higher speeds, the actual quality of the plowing job went down. They not only went faster but deeper too. Maybe it did stir the soil deeper but it was not the original job for which the mold board plow was invented for, turning up "new" weed free/rich soil for planting.

It was actually doing a pretty decent job - here's another shot taken the same day that shows the results. The #39 was advertised as a relatively deep plowing model and in flood irrigated land where these plows were popular going deep is typical. My Deere #44 2x14 would never be able to go anywhere near this deep.

Good info fellows.
Thank you one and all.

Brendon-KS I was not meaning to knock your plowing job. In stock ground I usually plowed deeper myself. I just meant in sod the plow would need set differently to turn the grass under better.

RN,
One year I borrowed my neighbors set of later model MF 12" plows with the kick back feature, they were a set of three plows with the center plow removed. Do not know the model number.

I though I would be able to pull them better, but I could never get them to follow my tractor properly, they wanted to pull to the left or right, no matter how much adjustment I gave them,

I just gave up, cleaned/greased them and put them back in the storage shed.

My old #62 3x12" plows will follow the tractor just like a trailer, if only it did not clog up so bad, it would be a great plow. 12" plow = smaller throat area.

Might be that an adjustable Gauge Wheel would be a good addition in those conditions...

Ron.

I do have one of those for the single bottom, but with trash clearance being a problem I have taken it off, but with some more experience using the plow, might have to take a 2nd look, given what it does and having a better idea of what the plow should be doing. Draft control or depth control with a gauge wheel would be nice given the tractor I was using.

I would not think that a Gauge Wheel would cause much of a problem with Trash clearance.

Usually positioned at or just forward of the second Coulter mount on a 3-Bottom, further back on larger plows..

Ron.