Yield and Stand Persistence of Switchgrass as Affected by Cutting Height and Variety

Abstract

Switchgrass (Panicum virgatum L.) is a high-yielding forage species with low input demands on marginal soils. However, long-term response of prominent varieties to cutting heights is not well documented. To examine varietal type and cutting height impacts, three varieties of switchgrass (‘Cave-in-Rock’, ‘Kanlow’, and ‘Alamo’) that were established in 1992 for a previous study were evaluated in Knoxville, TN, from 2008 to 2011. Switchgrass plots were harvested at 10-, 20-, 30-, and 41-cm cutting heights in a two-cut system (June and September annually) to determine if lower harvest height affected forage yield and stand persistence. Plots were visually rated during the final year (2011) to assess stand vigor. Interactions were detected for total yield by cutting height and year (P < 0.05); shorter cutting heights appeared to negatively impact yields in subsequent years and the highest cutting height resulted in lower yields. However, there were no varietal yield responses to cutting heights. Shorter cutting height treatments (10 and 20 cm) had reduced Alamo and Kanlow presence (P < 0.05) by the end of the 4-yr study period. Consequently, lower switchgrass cutting heights (10 and 20 cm) may maximize short-term forage yield; however, stand persistence may be compromised long term, especially in lowland varieties.