Tilling - Double-Digging? Need Advice

 Putting in my first organic vegetable garden next year, so forgive me if my
questions are a little naive.  I'm trying to get everything tilled up now
and let it rest all winter.  I've skimmed several books, one of which
mentioned "Double Digging" tilling.  Here's a parphrasing of the process:

Dig a 1 foot trench down the long side of the garden.  Keep the top soil in
the garden, but take the rest and throw it in a wheel barrow.  After
finishing the trench, go back and dig down another foot of subsoil and put
it in the wheel barrow.  (Sounds like a big wheel barrow).  Mix the subsoil
with peat moss and compost before putting it back in the garden.  Make the
mixture one third peat moss plus two thirds compost, plus one part subsoil.
Rake the top soil back into the trench, then add the new subsoil mix on top.
Dig another 1 foot trench and repeat untill garden is all tilled.  Tamp down
when finished.  Expect bed to be about three inches higher when finished.
Wait at least a month before planting.

Bascially, I wanted to ask the group if this seems like a sound method.  I'm
in western PA and my soil tends to be on the clay side.  I don't think I'll
go as deep as two feet, but because the garden area is new, I do plan to go
deeper than one would for standard tilling.  In particular, does the mix
sound right?  BTW, when they say peat moss, am I to assume they mean peat
hummus?  And for compost, I expect to use mostly manure (bags).  Is it
reasonable to assume the bed will only be rasied 3 inches?

There is still some grass on the plot I plan to use, and with winter coming
soon, I doubt I'll have time to cover it and kill it with black plastic.  If
I just till the grass under, and then cover it and let it sit all winter, I
should be fine, right?

Oh, this might be a dumb question, but...   If putting black plastic over
grass for a couple weeks kills the grass, why doesn't the grass die when
covered by snow all winter?

 

Answers answers..

Double digging is double digging, 'tilling' done with a tiller, is a
mechanised version of hand digging (a bit like ploughing) I suspect the
book may have UK terms in some of its origin. Peat moss is not incorrect
though I guess Moss Peat; that is, peat made from moss, is what is
referred to. It is humus as you describe.

The moss is just used to add humus.. You could equally add mature leaf
mould (2 - 3 year) or similar.

Compost can be of your choice. Matured animal manure is fine as is home
made compost (from kitchen waste etc). AS long as its partly rotted eg
NOT fresh.
Digging is often measured in the length of a spades blade or 'spits' so
you can substitute 'spit' for 'foot' in the measurements. Though I guess
it depends on how big a spade you use!-)


You can adapt double digging like this.

Remove your first spit depth trench of soil and move it to the 'end' of
the are you intend to dig. Fork manure/humus/compost into bottom of
second spit spit of soil.

Fill first trench with soil from 2nd and continue this method across the
area to be dug.
When you reach  end of the area you will have your soil from your
initial trench to fill in.


Lift the turf and stack upside down, covered under plastic. Next year
you will have a ready made loam pile for potting etc.

Snow lets through enough air and light and is naturally cold so
minimises growth. Black plastic only cuts out light and air.

//
Jim

 Thanks for the help Jim,



I have a little "home made" compost, but the rest will be store bought
bagged manure, which is certainly rotted.


But the rotted manure IS the compost, right?  And is the two thirds compost
+ one third (peat moss) humus about right in your opinion?


Hmm...   What you suggest sounds like a good tip for making good loam, but
is that necessary?  As I said, I have grass on the area designated for the
garden but it's spotty and useless as sod.  In the process of the Double
Dig, I was planning to just work the grass into the mix.  After I Double
Dig, I was planning to cover with plastic and leave it for all of winter.
Is there anything wrong with doing it this way?  It would save some work,
which is important with old man winter coming around the corner.


Ah, I figured it was something like that.  Thanks.


Thanks for your time and your advice Jim.

Oh, is there any kind of a generic calculation one can use for figuring how
much hummus and compost I'll need?  I really don't know how much to get.
BTW, my book says to expect the soil to be built up about 3 inches, but it
seems like adding all that hummus and compost will raise it much more than
than.  What do you think?

 
Well, you have an area for your garden, say it's 10' x 20'.
Multiply 10'x20'x(3inch)x(1foot/12 inch)
and you get 50 cubicfeet. (ft^3)

Most garden stuff is sold in either cubic feet or cubic yards.
1 yard^3  = 3ftx3ftx3ft' ft^3

You might be able to get away with a little less since tilling the
soil will fluff it a little.... but the more organic material the
better... ;)

good luck!


--
be safe.
flip
Verso l'esterno!  Verso l'esterno!  Deamons di ignoranza.

 Double digging,
A good idea if you have the time and energy.
The idea is to dig 2 "Spits" in depth a "Spit" is the depth of the blade of
your spade, don't worry about it being less than 1 foot.
Yes you take out a trench and put the soil aside, but to make life easier,
if your plot is 20 foot wide then treat it as 2 10 foot plots so put the
soil next to where you take it from. dig up to the end of the plot then back
down the other side. No heavy trucking of soil from one end to the other.
The idea of double digging is to break and pan that may have formed, to
improve the texture of the soil and to give the plant roots a greater depth
of usable soil.
As you dig, skim off any weeds from the top layer with about 2 Inches of
soil, and work this together with any form of humus, Peat, compost, manure,
other annual weeds etc and dig these into the lower spit,
then the top spit is dug to cover the lower dug spit, and so on till you
finish, then just replace the soil that came from the initial trench into
the trench you finish with.
If you are a real glutton for punishment you could even treble dig.
Double digging and treble digging were quite common during Victorian times
when labour was plentiful as was manure. In those days they also used a
system of making "Hot beds by taking out a trench about 4ft wide and 12 to
18 inches deep then building a bed 2ft of so high of fresh stable manure,
and covering it with the soil removed from the trench, this manure would
heat to over 160 F  then as it started cooling Glass frames were placed over
the bed and veg plants were planted, the heat from the manure giving the
plants bottom heat and frost protection, so that you could grow things like
lettuce, cucumbers, melons and a wide range of crops out of season.
This form of gardening could use up to 200 tons of manure a year.
Now back to topic. Tilling (Rotavating) is useful for rapid cultivation but
has the drawback of chopping up any perennial weed roots and thus spreading
them , and the blades will cause the soil at the base to form a "Pan" where
the blades rub along the bottom, especially if your ground is clay and is
wet, or even just damp when you work it, so digging is advisable every so
often.
On farms where the ground is "Rotavated" the use things like sub soilers to
break this pan and to help drainage.


--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk