Previous studies on the vegetation of set-aside have generally shown that annual species dominate set-aside initially, to be replaced by perennials as the sward matures. The most common colonising species are those which were persistent in the previous crops, those which have many seeds in the soil seed bank, and those dispersed from adjacent semi-natural habitats. Perennial species generally spread from the border to the core of the field as the field ecosystem develops. The most common grass species include Avena spp., Elymus repens, Alopercurus myosuroids, Bromus sterilis, Dactylis glomerata and Holcus lanatus. Common dicotyledenous species include Cirsium arvense, C. Vulgare, Rumex obtusifolius and Senecio jacobaea.
Studies on the characteristics of soil under set-aside have been almost entirely devoted to nitrogen changes and reductions in nitrate levels. Few papers give mention to other nutrients which are essential to plant growth.