Cattle treading effects on sediment loss and water infiltration

To quantify effects of forage canopy properties, soil surface relief, and hill slope on the hydrologic properties of the soil in a New Zealand hill land pasture, duplicate plots (15 x 3 m) with 3 canopy heights (6, 20, and 47 mm) were trodden with 0, 4, or 8 mature cows for 40 min on a moderate (15-18 degrees) slope (Trial 1), and similar plots with the low and high canopy heights were trodden by 8 mature cows for 40 min on gentle (8-14 degrees), moderate (15-18 degrees), or moderately steep (20-25 degrees) slopes (Trial 2). Pre- and post-treading measurements included canopy heights; bare soil proportions: soil moisture contents; hoof prints and skids; roughness coefficients. surface water detention storage volumes, and soil clump volumes with a 38-pin contometer; and water infiltration and sediment loss by rainfall simulation. In Trial 1, increasing canopy height resulted in lower (P < 0.01) proportions of bare ground, roughness coefficients, soil clump volumes, and sediment losses. Increasing treading damage resulted in higher (P < 0.05) post-treading roughness coefficients, proportions of bare ground, hoof print and skid densities, surface water detention volumes, and soil clump volumes. In Trial 2, soil hydrologic properties did not differ between canopy height or hill slope treatments. In the two trials, water infiltration rate was significantly related to the roughness coefficient (r(2) = 0.31) and the number of hoof prints (r(2) = 0.26), Results imply that a 20-mm canopy height of the forage species common on a New Zealand hill land pasture is adequate to minimize the effects of a short-term treading event on soil water infiltration rate and sediment loss.