Long-term effects of improvement methods on Molinia caerulea dominant rough grazing on wet hill land. 1. Pasture production, quality and botanical composition

Abstract

SummaryFifteen treatments were applied in 1966 to Molinia caerulea dominant rough grazing on wet hill land at 305 m in mid-Wales. Improvement methods varied from controlled sheep grazing, application of lime, basic slag and nitrogen to the introduction of grasses and white clover with and without cultivations. Pasture productivity, feed quality and botanical composition were studied in the 4th, 9th, 14th and 18th harvest years. Controlled grazing increased D.M. production from 1·1 t/ha on the native vegetation to 3 t/ha in the 18th year. Application of lime, basic slag and 75 kg N/ha gave mean pasture production of 4·5 t D.M./ha which increased to 6·3 t D.M./ha on application of 290 kg N/ha per year. The quickest and greatest improvement was achieved by the introduction of grasses and clover following rotary cultivation or ploughing. At the lower N input these swards produced on average 6·3 t D.M./ha. Reseeds also showed the best response to 290 kg N with mean production on S. 23 perennial ryegrass (Lolium perenne L.) swards of 9·0 t D.M./ha. In vitro digestibility, crude protein and water-soluble carbohydrates were also highest on the reseeded swards.Increased grazing eliminated Molinia before the 4th year and it was replaced by Nardus stricta and Festuca ovina. Subsequently, Agrostis tenuis replaced Nardus. On the swards given fertilizer the rate of botanical change was accelerated with the ingress of Poa spp., Holcus lanatus and Festuca rubra. The proportion of sown grass remained high on the seeded plots throughout the duration of the experiment but the white clover content was lower than expected and it virtually disappeared from most of the swards before the 18th year.The results show the potential improvement possible on wet hill land. Given good fertilizer and grazing management, this improvement can be maintained for several years.