Tuesday, 3 September 2013

Starting to clear and triple dig a new allotment (1)

I have just started to clear and dig the new allotment.  Late August and September are ideal times to begin to clear and dig an allotment.  The ground is usually dry and fairly friable.

This is how I clear and dig new ground.  It is not the way that most gardeners will begin a new allotment but I find that triple sieve digging clears out pernicious perennial weeds and large stones producing a reasonable finely tilthed soil that can be used immediately with few problems. I think that triple sieve digging produces a soil that ten years of conventional cultivation would produce.   I emphasise that this is the way that I do it; it is idiosyncratic but it works for me.

Most of this allotment has been covered by carpets and tarpaulins since February this year.  The only plants that can survive under the carpets are hedge bindweed Calystegia sepium (sepium means of the hedge- where I wish it would stay) and mare's tail Epiquestrum arvense (arvense means found on cultivated ground - particularly on my new allotment.)

Also, where there are gaps and spaces that have not been covered, plants like dock can survive.

Docks and bindweed growing through the
weed smothering carpet.
I do not like carpet on the allotment because of all the unpleasant chemicals associated with them.  Also, they attract rats which like to live underneath them.  I did not have any rats but I did have a family of field mice.  However, the carpets were on the allotment when I took it over so I decided to utilise them before finally taking them down to the tip.

At the trackway end of the allotment there was a bed of small rhubarb that had gone to seed.

Rhubarb along the trackway has gone to

Bindweed and mare's tail are growing
between the rhubarb plants.  

Wood has been used to weigh the carpets
I like to start clearing an allotment from an edge and the most suitable edge was the trackway.  It gives you a starting place.  I always find starting quite difficult because there is nowhere to put things.  The rhubarb needed to be dug out because it was full of bind weed and mare's tail.  Somewhere needed to be found for the top soil that was going to be removed from the first trench.

I was using old wooden planks and pallets to hold down the carpets and this needed to be removed.  It was put in a pile further down the allotment.  Rather than burn the wood, I was going to bury it in the trenches. Most hugelkultur uses relatively fresh wood but I decided that I would experiment with processed wood.  All the wooden planks were rotting in any case.

Rotten wood found on the allotment.  
There were only two options for this wood.  Either it would be burnt or buried.  I prefer burial because it produces a friable sponge like material when it is further degraded and can help with regulating water, irrigating the ground when the weather is dry but also allowing water to drain easily.  The ratio of carbon to nitrogen in wood is very high and there may well be a tendency for microorganisms to reduce the soil nitrogen in order to decompose the wood.  The wood will be buried quite deeply in the subsoil and any nutrients that the microorganisms find there they are welcome to.  Eventually they will be returned to the soil when the microorganisms die.  So just using the law of conservation of matter there will be no loss of nutrient - just a recycling.  I would suggest that there is less likely to be a loss of soluble nutrients through leaching because the microorganisms are capturing dissolved nitrogen salts as they pass the buried wood.

Even though I dislike carpets, I have to admit that they do clear the ground fairly well.

The carpet was folded back.
The surface bind weed stolons are being hoed and raked
off.  The soil will be sieved to get rid of the rhizomes.

A large dock  Rumex obtusifolius (Obtusifolius meaning
blunt leaved)

Long stolons of hedge bindweed.  
 Hoeing and raking the ground gave me a cleared space to start digging.

Rhubarb has large fleshy roots which can be a little difficult to dig out.    However with a little effort this can be achieved quite quickly. I cut the leaves off so that  the roots could be reached.  I started the trench  next to the runner beans and was surprised to find that the soil was particularly stony.

Stones and halfenders did not make digging out the
rhubarb roots very easy.
 Setbacks like this have to be expected when digging over a new allotment.  This soil will be sieved later and all these stones taken out.  If they are left they will make digging and planting much more difficult.

The fork had to be used to take out the soil.  

I will add the rhubarb and the dock seed heads to the
trench when I have dug it out.  
The rhubarb roots and perennial weeds were left on the carpets to dry out.

Bindweed drying out in the sunshine.
If bindweed and mare's tail is left to dry like this for several days - or weeks then there is an possibility that they will not regenerate.  Mare's tail roots are thickly suberised which gives them rubbery, flexible characteristics.  Drying them out means that they are unlikely to be able to absorb water through this waterproofing.  However, it also means that they will loose water very slowly so they will have to be left in strong sunlight for several days.

As the trench is dug the rhubarb roots come out fairly easily.  I am not going to keep this rhubarb because the bindweed is growing through the roots.  I don't know what variety this rhubarb is, so I would rather transplant named rhubarb from the old allotment.

Rhubarb roots are encountered as I dig backwards.

Taking the roots out is relatively easy.
The roots are removed and the top soil is put on one side.
The top soil still had a lot of bindweed and mare's tail in it together with large stones.  I will sieve the top soil as I put it back into the tench - but not yet.

The next spit of soil will be removed too.  I have used some of the carpet and black plastic to cover the weeds on the next allotment - it is mine too.  These will be used to make a base to put the subsoil.  I will dig out as much as is practical and leave  it on the carpets.

Beginning to take out the second spit of soil.  
Although in Victorian times there was a method of double digging where subsoil was placed on top of top soil, it is not very advisable.  I am keeping my sieved subsoil carefully separate from the top soil.  Not that you can see much difference because there is not much body in the top soil.  When a large enough trench is dug out the bottom is forked over to another spit depth and the organic matter is added starting with the wood.
Old processed wood added.

Brushwood cuttings and compost

This fills up the trench but I could add a lot more if I wanted.

This organic matter will be covered with sieved soil from
the next part of the trench.  
My trusty bread tray sieve is used to make sure that there are no large stones or rhizomes left in the soil.

I put the bread tray onto four tubs to raise it above the

Soil from the next part of the trench is sieved over the
organic matter.  
 I am making sure that the subsoil is kept separate from the top soil on the right.
I sieved quite a bit of subsoil through the sieve to make a
large trench.  
After the bottom is forked over to another spit depth more wood and organic matter is added.   Subsoil from the next part of the trench is then sieved to cover the organic matter.

And so I continue along the trench making sure that all the weed rhizomes are removed and the subsoil is kept separate from the top soil.

I am still removing mare's tail rhizomes even
at this depth.  

When the second spit is taken out the
bottom of the trench is forked over to
another spit deep. This is triple digging.

Processed wood is added.

The wood is covered with mare's tale and bindweed
rhizomes that were dried out carefully and composted for
a year.  

I don't think that they will regenerate but you can never
be sure.  
  I raked the subsoil back over the organic matter in the trench until the soil was level throughout the trench.

The subsoil is starting to look a little more
presentable now.  

The subsoil with fewer large stones and
hopefully no weed rhizomes.  
Now the top soil can be sieved and added to the trench.  It always looks a mess when you are trying to turn a dirty allotment around.  However, when you have finished a couple of trenches, it transforms the allotment and you can see its potential.

Sun is getting low in the sky and it is time to go home.

Still some more top soil to sieve but that can be done
It takes time, but I know that the soil is fairly clean  where I have dug.  Quite a satisfying days work particularly the tea breaks with ripe plums straight off the tree.

1 comment:

  1. Now here is a man not afraid of hard work and doing the job properly!

    Kudos Tony.