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.