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

Abstract

Historically, much of the New England landscape was converted to pasture for grazing animals and harvesting hay. Today, consumer demand for local, sustainably produced food, the number of livestock farms and the land area used for farming are increasing in Rhode Island. In order to make sound management decisions, it is important to characterize the effects of livestock on the quality of pasture soils. Although pastures remain a fairly common part of the New England landscape, little research has been published on the effects of grazing animals on pasture soil quality. To assess this, I examined soil quality in farms raising beef cattle, sheep, and horses, using hayed pastures as a control. All pastures were situated on ablation till. Three pastures per livestock type and three control hayed pastures were sampled in May, August and October 2012. I interviewed farmers about their management practices, made soil profile descriptions to a 50-cm depth, and characterized vegetation species. I established a 10 m × 10 m sampling area in each pasture and assessed soil quality based on measurement of physical (aggregate stability, bulk density, soil organic matter, infiltration, soil structure, texture and penetration resistance), chemical (soil pH, electrical conductivity, extractable N and P) and biological (active C, earthworm numbers, soil respiration) parameters, according to general agricultural recommendations in the Cornell Soil Health Training Assessment Manual. The effects of livestock type and sampling date on soil quality parameters were analyzed using a one-way ANOVA on ranks. Penetration resistance, bulk density, aggregate stability, organic matter content and extractable phosphate differed significantly (P<0.05) among pasture type. Hay and sheep pastures had significantly lower penetration resistance and bulk density than horse or beef pastures, whose values were in the ideal range for bulk density, but in the acceptable and problematic ranges for surface penetration resistance, according to general agricultural recommendations. For aggregate stability, hay pastures had the highest fraction of water-stable aggregates, followed by sheep and beef pastures, though all values for all pastures fell within the ideal range for agricultural soils. Horse and hay farms had significantly lower extractable phosphate concentrations than beef or sheep farms, with approximately 25% of horse pasture values within the problematic ranges for soil phosphate, according to agricultural soil guidelines. The remaining soil quality parameters (active C, vegetation, electrical conductivity, pH, extractable N, infiltration rate, and earthworm numbers) did not vary significantly among pasture types or season. Soil pH and