Soil compaction on Dartmoor

I’ve now seen first hand some compacted soils on the moor. We spent some time looking at some soils which should have good drainage qualities opposed to the peat water logged soils higher up.

Richard Smith (Environment Agency), Sue Everett (Sustainable Soils Alliance), Mark July (former Natural England) and Tim Harrod (former Soil Survey of England and Wales) inspecting a compacted soil on Peter Tavy Common

The compaction means that the water cannot flow into the profile as there is a layer of compressed (gleyed) soil which is impermeable – as a result this soil has a perched water table. When it rains hard the water flows across the surface and down the hill side. The Environment Agency are interested in ameliorating this so that flooding incidents in Peter Tavy can be reduced.

Here is a soil from the Moor Gate series which is not compacted – the soil is friable to the touch and shows no signs of compression or gleying. Heavy rain on this soil will flow down through the profile and not across the surface.

The general theory is that the compaction at say, Peter Tavy Common happened between 1960-1990 and main suspects were cattle and ponies.

The question now is do these soils have the capacity to repair themselves or are they permanently damaged? These compacted soils are often very acidic and as a result possess very poor soil faunas which could potentially undo the damage.

I would be interested to know whether the last 60 years of atmospheric nitrogen pollution has lowered the pH of these soils and as a result reduced the soil fauna’s ability to repair the soil structure.

Unfortunately I cannot find anything in the literature to evidence a progressive lowering of pH in upland soils over the past 60 years – does anyone know of any evidence for this?

Soils are now very high on Defra’s agenda and it seems that answering questions like this and finding a remedy for such upland soil compaction is a high priority.

However there is a problem. The organisation that could have answered this question The Soil Survey of England and Wales has been disbanded (1987) and today soil science is a low profile academic discipline meaning that there are very few qualified professionals around to carry out such studies.

This has mean that the publication of ‘Soils in Devon IX Soil Survey Record No. 117 by Dr Tim Harrod has been undertaken pro bono by a retired soil scientist from the former Soil Survey of England and Wales. It is a majestic piece of scholarship which should have been funded by the State and not by crowd funding!

 

Defra undoubtedly needs to invest in soil science and soil scientists as otherwise solutions to problems will all too often be based on speculation (as above and here) and not science.

A new report on managing soils to reduce flooding in Devon and Cornwall

Those of you who have followed my blog over the years will know that I have written a great deal about maize cultivation in East Devon and the detrimental impact that this has had, especially how it has led to flash flooding. See here for my historic maize posts!

Well today, out of the blue – at least for me, a new report has been published entitled ‘Soils and natural flood management – Devon and Cornwall. It is absolutely superb and you can download it here (N.B. it is 36mb).

It has been written by Richard Smith of the Environment Agency and has been peer reviewed by R.C. Palmer. I have quoted their classic 2013 paper where they demonstrated the devastating effects of maize cultivation on unsuitable soils (i.e. ones on slopes where the soils easily become compacted) many times over the past few years.

You can download that paper here.

This new report is over 70 pages long and gives detailed and geographically specific sets of recommendations on how soils can be managed appropriately to reduce flooding – maize cultivation features throughout and even when not specifically referenced it is clear that compacted soils and late harvesting lead to flooding and misery for those downstream.

Congratulations to the author and the peer reviewer on producing such an accessible and important report and well done too to the project management team i.e. the Environment Agency, the Devon Wildlife Trust and the West Country River Trust. There is also a wider partnership involved in this project known as the Catchment Based Approach – lets now get the message out.

Pleased to see my old employer the National Trust is involved!

So this report now needs to be distributed far and wide, read and acted upon!

Now if I were Michael Gove, I would give this report to my officials in Defra and tell them to incorporate the guidance and recommendations into their ‘Cross-compliance’ regulations which determine whether farmers can claim their subsidies – follow the guidance = get the money, ignore them and you don’t.

Likewise if I were a farmer around Exton, where I used to live and used to regularly view and fear the maize fuelled, brown/red river floods, farming in the area described as the ‘Soils of East Devon’ I would be reading this report very carefully – there are no longer any excuses for ignorance.

Finally whilst this report is about Devon and Cornwall the farmers in the hills above the Somerset Levels could and should learn a lot too.

Michael Gove yesterday attended and spoke at the launch of the Sustainable Soils Alliance where he said UK is 30-40 years away from ‘eradication of soil fertility’, ‘We have encouraged a type of farming which has damaged the earth’ and ‘Countries can withstand coups d’état, wars and conflict, even leaving the EU, but no country can withstand the loss of its soil and fertility’.

Maybe, just maybe we are turning the corner?