Soil Quality in Rhode Island Pastures Grazed by Different Types of Livestock.

Nearly 16% of Rhode Island farmland is currently under pasture. Very little research has characterized the effects different types of livestock have on pasture soils – information necessary for sound land use and management decisions. Common concerns about soil quality in pasture include increased compaction, lower infiltration, and the potential for increased run-off polluting downstream waters. In this study a total of twelve Rhode Island farms were chosen to be sampled three times: three farms raising one of each type of livestock (beef cattle, sheep or horses), as well as three independent hayed pastures (control) in May, August and October 2012. Values for physical (aggregate stability, bulk density, infiltration, soil structure, texture, and penetration resistance), chemical (soil pH, electrical conductivity, and extractable N P K), and biological (soil organic matter, active carbon, earthworm number, soil respiration, standing plant biomass, and root health assessment) soil quality parameters were examined. Preliminary data indicate that significant differences exist among pasture types in penetration resistance in the upper 25cm of soil (25 - 275 PSI) and in electrical conductivity (11.87 - 98.00 dS). In contrast, infiltration rate (1.3 - 101.6 cm/hr), bulk density (0.9 - 1.4 g/cm³), soil organic matter (3.19 - 11.37%), active carbon (272.1 - 950.3 mg/kg), soil respiration (30.3 - 97.0 kg C/ha/d), and earthworm population density (5 - 39 per 27000 cm³) did not differ significantly among livestock types or control. Neither pH (4.69 - 6.42) nor extractable NO₃^-, NH₄⁺ and PO₄^3- values (0 - 23.3, 0.6 - 20.5, and 0 - 109.2 µg/g, respectively) were significantly different among types of pasture. Data from this study will provide an objective baseline for the effect different livestock types have on pasture soil quality, and may influence land use considerations.