Root distribution in a low fertility hill country sward grazed by sheep

Abstract

In a preliminary study, root distribution, biomass, length, and surface area were measured to a depth of 800 mm in mid summer on a sunny (north) and shady (south) aspect of a low fertility hill country sward grazed by sheep. The dominant grass species were browntop (Agrostis capillaris L.), crested dogstail (Cynosurus cristatus L.), and yorkshire fog (Holcus lanatus L.). White clover (Trifolium repens L.), suckling clover (T. dubium Sibth. L.)(and lotus (Lotus pedunculatus Cav.) were the dominant legume species. Calculated root biomass for the profile down to 800 mm was 14 410 kg dry matter (DM)/ha on the shady face and 21 470 kg DM/ha on the sunny face. This was 2.3–3.5 times more than above-ground biomass produced on an annual basis and 6–7 times the total above-ground pasture biomass at the times of sampling. The large root biomass, and consequently the large quantities of nutrients involved in the below-ground component of the nutrient cycle, highlight the need for further research to quantify and characterise the root dynamics of grazed swards. © 1988 Taylor and Francis Group, LLC.