Abstract
Equine stocking densities in New Jersey generally exceed the current regional recommendation of 0.6 to 0.8 hectares per animal for mature animals. Our hypotheses that high stocking densities under continuous grazing systems affect the composition of pastures and increase soil phosphorus concentrations were tested in a field study of 40 horse pastures. Stocking densities were grouped into four treatments. Plant data were collected in the spring and summer to determine botanical composition and plant density. Soil samples were collected in the spring to measure soil chemical properties. Averaged across stocking density in the spring, Kentucky bluegrass (Poa pratensis L.) and annual bluegrass (Poa annua L.) represented 76% of the total grass density (392 and 297 tillers m
−2
, respectively). Common white clover (Trifolium repens L.) was the most dominant legume with a density of 289 stems m
−2
. In the summer, total grass density was greatest (P< 0.02) in the highest stocking density. Densities of all species declined in the summer compared to the spring except tall fescue under the highest stocking density, which increased 24%. Soil phosphorus concentrations were affected by stocking density (P< 0.05) and exceeded optimum levels for plant growth regardless of stocking density. Species that tolerate frequent grazing dominate horse pastures in New Jersey regardless of stocking density.