Ben Lawers Historic Landscape Project

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Uncovering the Past in the Soils of Loch Tayside

Sheilings at along slopes of Ben Lawers

The environmental, social, cultural and material past of Loch Tayside has been greatly influenced by the need to harness natural resources. For centuries people have relied on the land to provide building materials, crops, grazing, fuel. By the 1790s the population of the north side of Loch Tay had reached its peak at around 3,500. This expansion depended largely on the ability of farmers to provide adequate food for a growing population. By the eighteenth century agricultural land use in Scotland was characterised by labour-intensive techniques which have been shown to have a considerable impact on soil processes and properties. Management practices such as stone clearance, cultivation, manuring and grazing can be retained in soils for hundreds of years, and can provide a record of both landscape history and the nature of management systems in the past.

Soil Profile from shores of Loch Tay

The soils project has been underway since October 2003 to look at the impact of historical land management systems on soil properties today. For example, the construction of lazy-beds to improve drainage has had a considerable impact on the soil environment, including topsoil depth and chemical status of soils. The long-term application of manures and domestic waste in a historical context has been shown to lead to the accumulation of topsoil material, in some cases to depths of over 1 m. These soils are often characterised by high inherent fertility such as the Plaggen soils across northern and eastern Europe, and Terra Preta soils in South America. During fieldwork in May of this year, an accumulation of topsoil to depths of up to 70 cm was found adjacent to an abandoned seventeenth century farmstead at Kiltyrie (above left). Manures added to this soil have included domestic and human waste, animal dung, bedding materials such as bracken from the byre, and ash deposits from fires.

Prior to the agricultural improvements of the eighteenth century, the soils at Kiltyrie fell into the category of less fertile outfield land. Intensive cultivation and manuring from the late eighteenth century and to the early nineteenth century have modified both the physical and chemical characteristics. Changes include increased topsoil thickness, lower bulk density, elevated levels of organic carbon, total nitrogen and phosphorus, and higher levels of available phosphorus. Analyses of these soil properties are currently underway to explore a range of historical contexts, including infield land below the modern road, and sheiling sites above the head-dyke (below). Chemical signatures retained in the soil can also provide information on human activities, such as enhanced levels of lead, calcium, potassium and magnesium. Extractions of approximately 300 soil samples are currently being prepared for multi-element analyses at the University of Aberystwyth.

A sheiling hut now covered with vegetation and moss, used historically as shelter when grazing cattle away from the crops during the summer months

A soil profile located near to a sheiling site showing a distinctive Ah horizon with high organic matter content

Although the distribution of major soil sub-groups at all the sites is very much related to climate, topography and parent materials, the impact of man on the landscape through soil modification can still be clearly seen. The standard features of Scottish Highland farming settlements by the seventeenth century were strips and patches or rigs of arable adjacent to houses generally termed 'infield', areas beyond this used for grazing and periodic cropping known as 'outfield', and rough grazing and moorland areas which also provided important resource materials such as peat for fuel, building, and manuring. Cultivation above the head-dyke is unusual (above right), particularly since these humus-iron podsols are so shallow and exposed (below right). The use of thin section micromorphology enables the direct observation of human influences within the soil fabric (below). The effects of disturbances which may be seen in thin section include tree clearance, cultivation, manuring, pasturing and abandonment. Work currently underway also includes biological analyses of soil properties, including measurements of microbial activity combined with radiocarbon dating of soil organic matter. I also plan to utilise historical information such as Farqharson's 'Book of Plans' to quantify inputs and develop a model of organic matter turnover for the past 300 years.

Rig and furrow at Kiltyrie Soil profile showing shallow and exposed podsols

Thin section showing a small particle of burnt organic material derived from the addition of heath sods into the soil

Caitlin McFarland Stirling University [External Link]

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