Seasonal Yield Distribution of Cool‐Season Grasses following Winter Defoliation

Abstract

Graziers in southeastern USA often stockpile forage in late summer to extend the grazing season and reduce feeding costs. The effect of winter grazing on the following growing seasons production in the upper Midwest has not been reported. This study was conducted to determine the consequential forage yield and persistence of several cool‐season grasses following various winter defoliation and N fertilization treatments in the upper Midwest. Grass cultivars included early and late‐maturing orchardgrass (Dactylis glomerata L.), quackgrass [Elytrigia repens (L.) Nevski], reed canarygrass (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), and timothy (Phleum pratense L.). October, December, 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 fescue, 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 midsummer cuttings, the single N application resulted in higher seasonal forage yield than the split‐N application. Tall fescue had the greatest carryover response to N in both years. Orchardgrass and reed canarygrass provided the highest forage yields throughout the season. Tall fescue and both orchardgrass varieties were most persistent and timothy, smooth bromegrass, and quackgrass were least persistent.