ABSTRACT
IN IRISH AGRICULTURAL practice of the eighteenth and nineteenth centuries, the enrichment of the lime content of the soil was achieved in a number of ways. Limestone was converted into lime by burning which was then applied directly to the soil; limestone gravel, where deposits of it occurred, was spread on the ground and ploughed in; marl, a calcareous earth, derived chiefly from the shells of freshwater molluscs, was dug, weathered and either used as a top-dressing on lea or incorporated into tilth by ploughing and harrowing. Still another method, common in coastal districts, was the application of sea shells, where they were to be found in sufficient quantity, or, more usually, of sea sand containing a high percentage of their broken and comminuted remains. An allied manure, also of marine origin, was sand containing a large proportion of calcareous matter derived from the alga Lithothamnion calcareum. This was known as ‘coral sand’ and it occurs at a number of places around the Irish coastline. While the shells and sand were of less immediate benefit to productivity than lime, their influence was much more long lasting. The siliceous content of the sand exercised, in addition, its own effect: making heavy clay soils more friable and free-working. The present note endeavours to trace the history of the use in Ireland of these marine shells and sands as manures but, as no special research has hitherto been devoted to the subject, what follows can only be considered as a preliminary outline study.
