TOPOGRAPHIC AND MANAGEMENT EFFECTS ON BUNG DISTRIBUTION BY GRAZING SHEEP

Abstract

In both summer and winter, measurements were made of the rate of accumulation of dung by grazing sheep on both "easy"and "steep" land. The effect of the proportion of "easy" land (0, 25, 50, 75 or 100%) was studied in combination with grazing duration (3,6,9, 12 or 15 days) using a common pasture allowance in each situation. The rate of accumulation of dung was faster on "easy" than "steep"land, especially in summer. The rate of build-up in total dung tended to fall off during grazing and in this way largely reflected the pattern of pasture utilisation. In both seasons total dung accumulation tended to decline as the length of the grazing period increased. Correction for differences in pasture utilisation did not modify the trend and no other explanation can be offered at this time. In summer the most dung was collected from "easy" slopes when these occupied only 25% of the paddock. This effect did not occur in winter. Most dung was dropped on steep areas when they comprised the total paddock. Other less extreme variations in paddock topography had no obvious effect. Compared with other treatments the extra P provided in the highest total amount of dung on steep slopes was estimated to be about 2-3 kg ha/year. In order to achieve this, paddocks should, where possible, be fenced into topographically uniform areas either all "easy" or all "steep".