Friday, 6 May 2011

My soil

I took a photograph of my soil profile in 1992.  It is not like this now because the topsoil is about 3 feet deep.  The area where I dug this pit has been raised about one or two feet above this original level.
Soil profile 1992

The ruler is measuring the top soil and in 1992 it was about 1 foot deep.  I still had not drained the allotment and the allotment was regularly waterlogged during the winter.  

As far as I remember I was adding a great deal of organic matter to the soil and had double dug it but there seems to be little evidence of it in this photograph. You can see the soil is divided into very  distinct horizontal layers which are called horizons.  There is more organic material nearer the surface and more mineral content in the lower layers.  The subsoil is mainly clay because the allotment site is on a terminal moraine left there by the Welsh glaciers.

From the booklet:" Soil Types A Field Identification Guide" I think that this is a Stagnogley.  It is predominantly grey coloured with mottling present.  Soils which are poorly drained ,like my soil was, and are waterlogged for a number of months during the year are often given the prefix stagno showing that stagnant water conditions occur regularly.  

It would be interesting to compare this soil profile with the profile of the soil now that it has been modified by adding lots of carbon. Unfortunately, I cannot dig a hole like this because the allotment is nearly full of plants and there is no room to dig without damaging lots of plants.  

The soil has now been drained using a big pipe that stretches from where the spring used to be and runs to the  trackway where it flows down to the carpark.    The soil is rarely waterlogged now and it is very workable in winter.  I have also raised the allotment using any old organic matter I could find so that water is more likely to flow underneath the top soil.  

Bottom of the allotment 2008
When they changed the soil on Allotment 26(b), they thought that they had punctured a water main.  All that was happening was the water from the spring just slightly up the hill was flowing into the excavated area.  They tried to pump all the water out but I said just fill it in.  So they did.  I would have like to have dug over the area before they added the new soil but I was working and did not have the opportunity.  They filled the hole with some rubbish soil and I am still trying to improve it 3 years after it had been done.

I have a simple land drain that crosses the top of this area and under the path is 12 inches of stones that take the water away to a land drain running down this side of the allotment.

This area had the very best soil on the allotment site.  Unfortunately when it was tested they found some nasty chemicals and decided to change it completely.

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