Seasonal yield distribution of cool-season grasses following winter defoliation

Graziers in southeastern USA often stockpile forage in late summer to exten d the grazing season and reduce feeding costs. The effect of winter grazing on the following growing seasons production in the upper Midwest has not b een reported. This study was conducted to determine the consequential forag e yield and persistence of several fool-season grasses following various wi nter defoliation and N fertilization treatments in the upper Midwest. Grass cultivars included early and late-maturing orchardgrass (Dactylis glomerat a L.), quackgrass [Elytrigia repens (L.) Nevski], reed canarygrass (Phalari s arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue ( Festuca arundinacea Schreb.), and timothy (Phleum pratense L.). October, De cember, or March defoliation generally did not affect seasonal forage yield except when early spring growth preceded March defoliation, reducing first -cut forage yields. Without N, timothy, reed canarygrass, and orchardgrass had the highest seasonal forage yields. Both orchardgrass varieties, tall f escue, and reed canarygrass had the greatest response to N whereas timothy had the lowest response. While both spring-applied N treatments (single and split application of 101 kg ha(-1)) had carryover effects into the midsumm er cuttings, the single N application resulted in higher seasonal forage yi eld than the split-N application. Tall fescue had the greatest carryover re sponse to N in both years. Orchardgrass and reed canarygrass provided the h ighest forage yields throughout the season. Tall fescue and both orchardgra ss varieties were most persistent and timothy, smooth bromegrass, and quack grass were least persistent.