Managing Global Resources for a Secure Future

Pasture growth rate varies with developmental stage, environmental conditions, and timing and severity of defoliation. Relationships of growth rate and total-season herbage production to canopy leaf area index (LAI) across defoliation stages including late maturity are not well-defined for cool-season mixed-species swards in the Appalachian region. We hypothesized that pasture growth rate and total-season forage production will be less for relatively few harvests of late-maturity pasture at LAI>8 than for more-frequent harvests at LAI <4-6. We compared LAI and growth rate of perennial pastures containing cool-season grasses, legumes, and non-legume forbs under defoliation frequencies and residual heights simulating continuous and rotational stocking and ranging from a) every 7-10 days to 8 or 13 cm; b) periodically from 25-30 cm to 6 or 12 cm; and c) periodically from mature hay stage to 6 or 12 cm. Herbage mass was estimated with a calibrated rising plate meter and LAI was estimated from canopy light interception measurements with a line quantum sensor. Responses of growth rate and total-season herbage production to LAI at defoliation will be presented.