Effect of rotational grazing on selected physical properties of a Gleyed Brunisolic Gray Luvisol loam in Nova Scotia

Low organic matter content and weak soil structure, combined with high annu al precipitation, make the soils of the Maritime Provinces extremely suscep tible to compaction. Although many pasture studies have been conducted in t he Maritime Provinces, none has investigated the impact of pasturing cattle on soil physical properties. Soil properties such as resistance to penetra tion, bulk density and hydraulic conductivity were monitored on pasture swa rds receiving various rotational-grazing intensities. These parameters were measured concomitantly on traffic-free areas that had been harvested as co nserved forage. Resistance to penetration measurements indicate that a sign ificant amount of compaction by cattle occurred during the 1990, 1991 and 1 992 grazing seasons. Penetration resistance was generally greatest in the t op 6 cm of soil, but was alleviated by frost action during the subsequent w inter and spring. The other soil parameters measured were either more varia ble (surface and subsurface saturated hydraulic conductivity) or less sensi tive (bulk density) to compaction. Although more variable, surface hydrauli c conductivity was significantly higher in the traffic-free conserved forag e areas than in the pasture paddocks. Rest intervals between gratings had n o significant effect on saturated hydraulic conductivity. Seasonal change i n resistance to penetration generally increased as rest interval decreased. The timothy/alfalfa swards (little alfalfa was left in the pastures by 199 2) had the least seasonal change in resistance to penetration.