Using a browntop millet companion crop to aid native grass establishment

Abstract

AbstractThe lack of forage production during the seedling year is a barrier to wide‐scale adoption of native warm‐season grasses (NWSG). To address this, two NWSG establishment experiments were conducted in Knoxville, TN, 2016–2018, to determine the efficacy of big bluestem (BB; Andropogon gerardii Vitman) and switchgrass (SG; Panicum virgatum L.) establishment with browntop millet [BTM; Urochloa ramosa (L.) Nguyen] as a companion crop. Each experiment was a randomized complete block arranged as a 2 × 3 factorial. Two defoliation strategies [(1) harvests based on BTM maturity (boot to heading stage) for hay (HAY) or (2) clipping to control BTM competition by maintaining >50% sunlight reaching BB and SG seedlings (CLIP)] were coupled with three BTM seeding rates [0 (control), 11.2 (half‐recommended rate), and 22.4 (full‐recommended rate) kg pure live seed (PLS) ha−1]. Only BTM seeding rate affected BB and SG plant density at dormancy. In all cases, the control had greater BB and SG plant density than the full‐recommended rate, indicating that BTM impeded BB and SG establishment. All BTM seeding rates resulted in acceptable stands (≥5.4 plants m−2) of BB (both years) and SG (2017 only). Only the control allowed for acceptable stands of SG in 2016 (8.5 plants m−2). Managing BTM for HAY produced a mean cumulative dry matter (DM) yield of 3.15 and 2.68 Mg ha−1 in 2016 and 2017, respectively. These findings show that BTM can be a companion crop that helps offset production losses during BB and SG establishment.