Disc Harrows: Tandem vs. Offset.

[Poopdeck Pappy]

The diffence between the two types of discs harrows is that an offset disc will allow deeper penetration but it is harder to keep the soil level and the opposite is true for tandem discs. In a tandem disc the longitudinal force exerted by the disc blade is offset by the longitudinal force exerted by another disc blade on the oppisite side. This causes the disc harrow to tend to want to float. With an offset disc the tendency for the harrow to float is decreased due to no oppisite disc blade.

My experience is that an offset disc will always penetrate and plow better than a tandem, even when both are heavy duty. I don't know why, but your explanation makes as much sense as anything else I've heard.

 

[MtnViewRanch]

This is what we pull with our Sears SS12. At 992lbs per blade, it can be a bit much when it gets down to the hubs though. :sarcastic:

 

[Poopdeck Pappy]

This is what we pull with our Sears SS12. At 992lbs per blade, it can be a bit much when it gets down to the hubs though. :sarcastic:

I'll bet penetration isn't a problem with that one!

 

[jeff9366]

(( I have never heard of a towed Tandem Disc Harrow. ))

I SHOULD have written: (( I have never heard of a towed Tandem Disc Harrow appropriate for a 18-40 horsepower compact utility tractor. ))

 

[sixdogs]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil. Apparently the side action of the blades pushing against the soil is responsible. Don't blame me--that's what I have read.

 

[Gary Fowler]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil. Apparently the side action of the blades pushing against the soil is responsible. Don't blame me--that's what I have read.

Not saying the article was wrong just F.O.B.S. Clay or any other soil doesn't compact from disking. When tilling clay, it has to be done at the right moisture content. Too wet and you will have concrete like clods of dirt to contend with all year, too dry and it gets too hard to penetrate with any thing less than the one MtnViewRanch posted. I have never heard of anyone measuring side loading of soil and calling it compaction. Anytime any responsible person mentions compaction they are referring to vertical compaction which in farming is mostly caused by the tractor tires and occasional use of a sub-soiler or chisel plow to break up the hard pan takes care of that.

 

[jeff9366]

Each individual offset disc could be thought of as a heavy, concave, relatively thin, steel tire, unsupported by the soil surface, with a much higher loading per square inch than a pneumatic tractor tire. Below the cut soil you have compaction.

Harrow can cut/chop/throw/mix to the depth of the disc hubs, which may be ample for the root structure of the crop, but below bottom of the sunk disc(s) there is compaction.

Depending on local soil, of course.

In principle, ANYTHING which moves over the field, in contact with the soil, causes SOME compaction. Examples:
LS7010 tractor, harrow of any description, RTV900 utility vehicle, truck, horse, sheep, baseball, elephant, mice, snake.

Depending on local soil, of course.

Don't be mad, now, I am attempting a little levity.

 

[jeff9366]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil.

When do you find time to read outside TractorByNet?

 

[MtnViewRanch]

I SHOULD have written: (( I have never heard of a towed Tandem Disc Harrow appropriate for a 18-40 horsepower compact utility tractor. ))

Now you have. Here it is. Now it does not have any HP rating, but at 235lbs total weight, it shouldn't be much of a problem

 

[N80]

Now you have. Here it is. Now it does not have any HP rating, but at 235lbs total weight, it shouldn't be much of a problem

I doubt compaction is an issue with that one......penetration probably isn't either.....