Intervals of superphosphate application to downland permanent pasture

Abstract

1. Superphosphate, at two levels and three intervals of application, was applied to calcareous downland pasture grazed by sheep over a period of 3 years.2. At the high level, total dry-matter and crudeprotein yields were higher from a single initial application and from thrice-yearly applications than from annual applications.3. At the high level, mean herbage phosphate content and total phosphate yield were higher following a single initial application than when superphosphate was applied at shorter intervals.4. Superphosphate increased the cover of grasses and legumes and reduced the cover of herbs.5. Superphosphate affected the cover of individual species in the following manner:(a) Favourably: Dactylis glomerata, Festuca rubra, Arrhenatherum elatius, Poa trivialis, Holcus lanatus, Lolium perenne and Trifolium repens.(b) Unfavourably: Agrostis stolonifera, Leontodon spp., Prunella vulgaris, and other minor herbs.(c) No measurable effect: Poa pratensis, Plantago lanceolata, Ranunculus bulbosus and Crepis capillaris.