Land Restoration and Reclamation
James A Harris, Paul Birch, John Palmer
Reclamation of Calcareous Grassland, page 194
Legumes will thrice on calcareous grassland and should be encouraged by the addition of phosphate
Research into the history of farming in the Adur area (mid-19th century) especially Applesham Farm on the Lancing side indicated that the phosphate was introduced on to the land for the specific purpose of increasing the density of sheep to one per acre. The idea was to increase fertility to benefit grass useful for sheep at the expense of herbs and legumes like Horseshoe Vetch (which are not eaten by sheep and toxic to almost every animal except the caterpillars of the Chalkhill Blue, Adonis Blue (butterflies) and the Dingy Skipper.
Conclusion: Phosphate is contra-indicated. Grazing confers no advantages in chalkhill down original unimproved herbland for biodiversity advantage. The addition of phosphate is improving the land.
Grazing may confer advantages on "improved" grassland designated as pastures.
Original chalkhill may be so rare that it would not fit into the standard classifications. Grass may not be dominant, under 50% of the plants by quantity.
Mill Hill Reports 2009
Mill Hill and its Butterflies
History notes addenda:
1791 Southdown Sheep (improvement of the breed 1788) introduced to Erringham Farm, north of Shoreham . By 1829, his flock attracted international attention because of improved fleece and superior mutton. (ref: Peter Brandon, the South Downs, 1998). Later records (mid-19th century) indicate the land was unsuitable for the sheep and it was the Lancing Downs (Applesham Farm) that developed the local sheep industry.
Adur Valley Nature Notes
Adur Valley Nature Notes: December 2009