Influence of Cool-Season Annual Grasses on Perennial Grass and Legume Establishment.

Perennial grass establishment into marginal cropland is challenging. However, success may be increased using seedbed preparation and crop residue from previous crops.  The objective of this study was to evaluate seedling establishment for three cool-season perennial grasses, ‘Lincoln’ smooth bromegrass (Bromus inermis Leyss.), ‘Beefmaker’ intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D. R. Dewey] and ‘Hycrest’ crested wheatgrass [Agropyron cristatum (L.) Gaertn. x A. desertorum (Fisch.) Schult.], and three warm-season perennial grasses, ‘Bonanza’ big bluestem (Andropogon gerardii Vitman var. gerardii Vitman), ‘Nebraska 54’ indiangrass [Sorghastrum nutans (L.) Nash], and ‘Trailblazer’ switchgrass (Panicum virgatum L.) seeded following small grain harvest in oats (Avena sativa L.), cereal rye (Secale cereale L.), wheat (Triticum aestivum L.), and triticale (Triticosecale Wittmack).  This experiment was conducted at Mead, NE during 2005 as a randomized complete block design with four replications in a split plot arrangement of treatments.  Whole-plot treatments were small grain species plus a non-planted control and sub-plot treatments were perennial grass species.  Cool-season grasses were seeded the fall following small grain harvest and warm-season grasses were seeded the following spring. Herbicides or fertilizers were not applied.  Frequency of occurrence and weed cover was measured 30 days after planting.  Intermediate wheatgrass and smooth bromegrass established well in all treatments with seedling frequency of occurrence exceeding 95%. However, crested wheatgrass frequency of occurrence was not greater than 20%.  Frequency of occurrence for indiangrass was greater than 50% following triticale and wheat, but lower following oats and cereal rye.  Big bluestem frequency of occurrence was approximately 45%, but switchgrass never exceeded 30%.  Planting perennial grasses after small grain harvest had no effect on establishment. Greater frequency of occurrence resulted in reduced weed cover for all cool-season perennial grasses.  Small grain residue may add the benefit of reduced weed competition, especially for species with increased seedling vigor.