A Preliminary Survey of Soil Aeration Conditions in a Scottish Hill Grazing

Abstract

In a previous communication (Poel 1960) an instrument for the estimation of oxygen diffusion rates in soils in situ was described and data were given suggesting that the meter readings provide a good estimate of aeration status at the soil-root interface. The present paper concerns estimations of oxygen diffusion rate and soil pH made during the summer of 1958 at Ballochraggan, Port of Menteith, Perthshire, a hill grazing which was formerly the Bracken Eradication Experimental Station of the West of Scotland Agricultural College. Ballochraggan occupies an area of 413 acres (167 ha) ascending northwards from the Stirling-Aberfoyle road at 148 ft (45 m) above sea level to the crest of the Menteith Hills, an altitude of 1150 ft (351 m). At approximately the 700 ft (213 m) contour, there is a grassy ridge or 'drum'. Below the drum, the vegetation is mainly composed of Agrostis-Festuca grassland with Pteridium, together with numerous 'flushes' dominated by Juncus acutiflorus. Areas of Holcetum mollis, Juncetum effusi and Molinia-Nardus vegetation also occur. On the north side of the drum, the land falls to a plateau averaging 600 ft (183 m) altitude. This region is locally dominated by Pteridium, Pteridium in AgrostidoFestucetum, and Calluna. In the lower-lying parts, Eriophoretum vaginati is found, especially towards the east, while in the west, Juncus acutiflorus flushes occur. The area up to and including the plateau was mapped in detail to a scale of tin. (2-5 mm) to 10 ft (3 m) between 1943 and 1947 (Poel 1949). The large scale of the map and the fact that landmarks such as large rocks, boulders and trees were included, enables the site of any observation or estimation to be recorded precisely and to be readily located in the future. Thus the sites of all the estimations reported in the present paper are known and can be reinvestigated at any time in the light of changes in vegetation and drainage conditions.