A simple vigor test for adjusting switchgrass seeding rate in marginal and fertile soils

Abstract

Calculating switchgrass (Panicum virgatum L.) seeding rate is misleading and often causes stand failure. Our objective was to introduce a simple vigor test to adjust the seeding rate and enhance switchgrass establishment and productivity in the establishment year in fertile and marginal soils. Seeding rate for four switchgrass varieties ('Blackwell,' 'Carthage,' 'Cave-in-Rock' and 'Shawnee') was adjusted ranging from 25 to 125% based on a vigor test. Results indicated increase in seedling emergence and establishment with increasing the seeding rate. Higher established seedlings were recorded from the fertile soil (131 seedlings m-2) compared with the marginal soil (78 seedlings m-2). Based on our previous findings, 100 established seedlings often is considered as a successful establishment; therefore, a 50% (6.89 kg ha-1) and 100% (13.82 kg ha-1) adjusted seeding rates could provide sufficient stand density (111 and 94 seedlings m-2) in the establishment year in fertile and marginal soils, respectively.