Acidifying arable soils for the restoration of acid grasslands

. Minsmere is a large nature reserve in East Anglia UK, owned and managed by the Royal Society for the Protection of Birds (RSPB). Two blocks of land, which were farmed commercially until 1990, have been bought in an attempt to link existing patches of heathland and acid grassland, thus creating a larger area for conservation. This paper discusses methods for the creation of acid grasslands. Previous studies of the arable soils in these fields identified three constraints -a depauperate seed bank, a high pH and vigorous growth of ruderal species after the fields were abandoned. Accordingly, experiments were set up to test the effects of (1) adding seed of species typical of acid grasslands and (2) adding amendments (elemental sulphur, litter of Pteridium aquilinum and pine chippings) to acidify the soil. The results confirmed that ruderal growth was high on unamended plots, but this could be reduced by addition of acidic amendments. Where the cover of ruderals was reduced, the cover of the sown species increased. The sown species colonized adjacent unsown subplots naturally and this was most pronounced where the acidity had been reduced by treatment. The most effective treatment was 21 S/ha, which gave the optimal reduction in soil pH, controlled ruderal growth and provided a reasonable cover of the sown species. The addition of Pteridium litter or pine chippings gave good establishment of sown species, but control of the ruderals was less effective.