Some effects of fertilizer and frequency of defoliation on the botanical composition and yield of permanent grassland

Abstract

AbstractSmall plots of permanent pasture containing 50%Agrostis capillaris‐Festuca rubra were defoliated frequently or infrequently during the growing seasons in 1978–80 and fertilized with 133, 125 and 125 kg N, P2O5 and K2O respectively ha−1 a −1 or not fertilized during 1978–81. Yields of herbage were assessed during 1979–80 and botanical composition assessed on three occasions in 1978, once in April 1979 and once in 1982.Fertilizer application increased annual dry matter (DM) harvested from frequently cut plots by 40%, 53% and 65% in 1978, 1979 and 1980 respectively, and on infrequently cut plots it doubled hay DM harvested in 1978 and increased total DM harvested by 126% and 186% in 1979 and 1980 respectively. Infrequent cutting and fertilizer both decreased the proportion of A. capillaris but only fertilizer decreased the proportion of F. rubra. Fertilizer greatly increased the proportion of Holcus lanatus especially where plots had been cut frequently and of Alopecurus pratensis where they had been cut infrequently. It decreased the proportion of Luzula campestris. Infrequent cutting, especially with fertilizer, discouraged Cerastium fontanum ssp. glabrescens and Trifolium repens but encouraged Rumex acetosa.