COSMIC: Trials at Cranfield's National Soil Resources InstituteArchaeological sites have been suffering from plough-damage since the first ard was dragged across the ground. But how do you assess the risk level to individual sites? Since 1999 OA South has been working on a model to assess what factors are involved in damage caused by cultivation, and to establish how best they could be managed.

An initial three-year project, ‘The Management of Archaeological Sites in Arable Landscapes‘, was commissioned by Ministry of Agriculture, Forestry and Food (Maff, now Defra) and subsequently developed into a follow-up project funded by English Heritage, entitled 'Conservation of Scheduled Monuments in Cultivation' – COSMIC for short.

If farmers are to be asked to change their cultivation practices in order to protect archaeological remains, then the new management methods recommended must be scientifically designed and appraised. The project therefore sought to provide a model that would provide an accurate and objective assessment of the mechanisms involved in damage to archaeological sites. The model was developed using data from 159 scheduled sites and 39 non-scheduled sites, all in the East Midlands. Data was collected on each site’s geology, topography, rainfall, soils, and archaeological attributes, as well as information from the farmers/landowners themselves on past and present land management, all of which was fed into the risk model.

We then undertook experimental trials at the National Soil Resources Institute at Cranfield, investigating the effect of different types and weights of machinery on soil compaction, the influence of tyre pressure and type, and the resultant pressures recorded at various depths, and their effects on buried artefacts. Detailed studies were also undertaken, using pottery and human bone, to examine the mechanisms and pressures involved in the breakage of buried artefacts. These experiments were replicated and tested in the field using a variety of different types of agricultural machinery over constructed archaeological sites with buried features, artefacts and pressure sensors. These trial sites investigated the relative effects of mouldboard ploughing, shallow ploughing, minimum tillage, and direct drilling. A series of dummy archaeological earthworks were also constructed which were subject to a simulated 30-year phase of cultivation to investigate soil movement, changes in surface topography and below-ground disturbance.

The upshot of this was a model of the effects of different agricultural and soil management regimes on earthworks and buried archaeological remains, and to provide soil management recommendations for protecting archaeological sites. The project also looked at the most effective ways to monitor disturbance to the soil, using objects buried at specific depths and using various sizes and configurations of RFID transponders.

The final results of the project will now feed into the latest phase of COSMIC, which involves using the risk model to assess all sites thought to be at risk from arable across the whole of England. Once their actual risk is assessed the sites at highest risk can be targeted for management change through Defra’s Environmental Stewardship Scheme or through  individual, site-specific management solutions