Overseeding cool‐season annual grasses into dormant lowland switchgrass stands

Abstract

AbstractImproved use of the land resource used to grow switchgrass (SG; Panicum virgatum L.), whether for biomass or forage production, could be achieved by dormant‐season overseeding with cool‐season annual grasses (CAGs). Cereal rye (Secale cereale L.), ryegrass (Lolium multiflorum Lam.), and wheat (Triticum aestivum L.) were overseeded into an established, mature stand of lowland (‘Alamo’) SG for two consecutive years (2010–2011) at a study site located near Greeneville, TN. Three harvest timings were imposed on CAG (15 April, 1 May, and 15 May). Yield of CAG differed (p = 0.001) by year, species (rye = 6.8, ryegrass = 5.0, wheat = 5.1 Mg ha−1), and harvest time (15 April = 2.7, 1 May = 6.5, 15 May = 7.7 Mg ha−1), but these factors did not interact. Switchgrass yield the summer following establishment of CAGs differed (p = .001) by year (11.1 and 14.7 Mg ha−1, in 2011 and 2012, respectively) but not by CAG species or harvest date. Tiller density of SG followed the same pattern as yield (2011 = 75 m−2; 2012 = 147 m−2). Thus, this study provided no evidence that any of the three CAGs, when planted for two consecutive years into dormant SG, regardless of harvest date, had a negative effect on SG yield or stand vigor; therefore, overseeding CAGs may be a practical way for producers to improve land resource use when growing SG. However, evaluation of production costs for CAGs indicated that May harvests would be required for overseeding to be cost‐effective.