Subsoiler leg spacing

Jim Bullock

Never Forgotten
Honorary Member
I am sure it has been covered before, but what is the optimum spacing for subsoiler legs v working depth? I know the shallower you work the closer the legs need to be but I seem to remember somebody (Philip Wright?) coming up with a formula.
 

strawturner

Member
Location
East Midlands
It depends on your wing width as well I think, My spaldings flatlift has 5 legs spaced 750mm apart with 300mm wings, working to about 12in deep most the time for me, next year I am going to add a leg so spacing will be 600mm (overall working width reduced slightly), reduce wing width to about 200mm, depth will remain similar but perhaps a little shallower 9-11 in.

Doesn't really answer your question though!
 

Alistair Nelson

Member
Mixed Farmer
Location
E Yorks
Yes as Nick said twice the working depth is the old school formula in good conditions for total soil shatter it can be increased with big wings on the points but on the other side of the coin reduce the spacing if conditions are less than ideal and you still feel you must go

Alistair
 

Iben

Member
Arable Farmer
Location
Fife
It depends on your wing width as well I think, My spaldings flatlift has 5 legs spaced 750mm apart with 300mm wings, working to about 12in deep most the time for me, next year I am going to add a leg so spacing will be 600mm (overall working width reduced slightly), reduce wing width to about 200mm, depth will remain similar but perhaps a little shallower 9-11 in.

Doesn't really answer your question though!

Is 9-12" really subsoiling? Plough deeper than that!
 

Farma Parma

Member
Arable Farmer
Location
Northumberlandia
30" on the Tim Howard here 3 legs & its about right id say as you want to be hitting the middle of each tramline & about halfway inbetween is spoton.
Generally 12-14" depth. sometimes more
Plough at 9"
 

strawturner

Member
Location
East Midlands
Is 9-12" really subsoiling? Plough deeper than that!

As above depends on soil and moisture really, some of the clay land we have, only has 12in of topsoil some will smear below a certain depth in all but the driest years, there would be little benefit going deeper, on the lighter loams we have, drainage is never really an issue and even though I could subsoil 18in deep we would see no benefit. Not to mention breaking drains etc, we would normally plough 8-10in
 

Michael S

Member
Arable Farmer
Location
Matching Green
I think for fuel efficiency you shouldn't go below a depth of half the tine spacing, however that assumes the tines are mounted in a row, but if mounted with alternate tines in different rows I'm not sure that applies. Also the depth shouldn't be more than six times the width of the foot under normal dry conditions, less if it is wet, or the soil won't be lifted but instead it will be compacted just above the foot. That is why subsoiling in the wet should be avoided.

As for those of you with loads of top soil you should know how lucky you are, here we have flecks of subsoil showing when ploughing 8 inches deep in most fields.

Michael
 

Brisel

Member
Arable Farmer
Location
Midlands
The critical depth limit for a tine is 6 times the width of the tine. Deeper than this & the heave will fail due to compression resistance. To go deep the obvious method is to add wings, hence why subsoilers have them. 2' (60cm) spacings on your subsoiler legs with 9" point+ wing allows you to work a max depth of 54" or a theoretical limit of 4'6"! The exception to the rule is a mole plough but you're not really looking for shatter above the point though it's a side benefit if the soil is plastic at mole depth & friable above that.

To move the whole soil profile at a shallower depth you'll need a narrower spacing, which was Jim's question! Different soil types will need different spacing for the same depth & outcome. See the attachment for a better understanding on how it all works.
 

Attachments

  • Spoor et al subsoiler MAFF report.pdf
    81.1 KB · Views: 33

Stephen E

Member
Mixed Farmer
Location
South Northants
We use a Tim Howard subsoiler with 6" wings at 10 - 12" deep and a leg spacing of 18". By altering the toplink length the pitch on the feet is increased or decreased which ensures the soil is loosened across the width depending on how dry or damp the soil is. It works really well without boiling the surface too much.
Tim Howard Subsoil 031.jpg
 
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