Location: Dairy Forage Research
Project Number: 5090-21000-056-25-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 23, 2014
End Date: Jun 22, 2018
Specific objectives of this agreement are to determine the impact of forage maturity stage at grazing and ruminant stocking density on: 1) forage sward characteristics including herbage productivity, interannual yield variation, legume specie yield and persistence, and sward diversity; and 2) soil characteristics including nitrogen and carbon cycling, organic matter, microbial activity, bulk density and compaction.
A temperate grass sward typical of the Northeastern and Midwestern United States that is located at the U.S. Dairy Forage Center Research farm will be over-sown with alfalfa, red clover, white clover, and birdsfoot trefoil or no legume in replicated large plots. Before treatments are implemented, baseline measurements of soil chemical, physical, and microbial properties will be taken at 10-cm increments to 30-cm depth. Plots will be grazed during the growing season with Holstein heifers at two stocking densities to a 15 cm residual sward height whenever swards reach a vegetative or mature stage. At each grazing event, herbage yield and nutritive value, and sward botanical composition will be measured. Soil microbial activity and physical properties will be measured at regular intervals aligning with the grazing schedule. At the end of the grazing season, legume persistence will be evaluated, and soil physical, chemical, and microbial measurements made at the beginning of the study will be repeated. Treatments and measurements will be repeated in year two.