Soil Limitations to Agrarian Land Production in Premodern Iceland

Early arable activity in Iceland, introduced in the late ninth century A.D., has been characterized as marginal and at a subsistence level, largely abandoned by the 1500s as a result of climatic deterioration. This view has been advanced without considering soils data, the medium in which crops are grown and in which evidence of early land management is retained. Soil thin section micromorphology together with soil total phosphorus values are used to assess land manuring and cultivation strategies at two sites in south-west Iceland, where place name and palynological evidence indicate that arable activity has taken place. Agro-ecosystem modeling, using the CENTURY model, is undertaken to predict grain yields at these sites, and to assess the significance of soil properties and soil management in determining yields. The results of these analyses demonstrate that manure application rates were low, and support the view that grain yields were at a subsistence level. The results also suggest soils, and the management of soils, rather than climate was the major limitation to arable production. Shortages of both available manure and labor are suggested as barriers to soils and grain productivity improvements in early Iceland. The paper highlights the need to include soils analyses in discussions of early agricultural economies.