Residue Management Strategies for Kentucky Bluegrass Seed Production

Abstract

Open‐field burning provides effective, economical post‐harvest residue management in Kentucky bluegrass (Poa pratensis L.) seed crops, but public concern over air quality necessitates the identification of nonthermal management strategies. On‐farm trials were conducted in Oregon's Grande Ronde Valley to investigate the effect of nonthermal management in two cultivars of Kentucky bluegrass on crop regrowth, seed yield, and seed quality. Residue treatments imposed after the first, second, and third seed harvests included (i) removal of straw by baling (Bale), (ii) baling, flailing with a rotary scythe, followed by residue removal with a needle‐nose rake (Rake), (iii) baling, followed by removal of the residue by vacuum‐sweeper (Vacuum), (iv) flail‐chopping residue three times with no removal (Flail 3X), and (v) open‐field burning (Burn). Tillers were etiolated at the cessation of fall regrowth in Flail 3X (stubble height reduced, no straw removal) and Bale (no stubble height reduction, 75% straw removal) treatments. Fertile tiller number was lower in the following spring with Flail 3X and Bale treatments compared with Burn. Seed yield averaged across the 3‐yr period was reduced 38% when managed with Flail 3X and 10% when managed with Bale compared with Burn. Crop regrowth, fertile tiller production, and seed yield resulting from Rake and Vacuum treatments were equivalent to the Burn treatment. Rake and Vacuum treatments reduced stubble height and removed at least 90% of the straw. High seed yield and seed quality can be maintained in Kentucky bluegrass without open‐field burning when straw removal is thorough and stubble height is reduced prior to crop regrowth.