Perennial grass establishment in relationship to seeding dates in the northern Great Plains.

Abstract

A 3-year field study with 5 species and 11 seeding dates per year was conducted to determine which dates resulted in successful stands when directly seeded into wheat stubble at each seeding date at Mandan, N.D. There was considerable range in the monthly highs and lows for many of the environmental parameters collected during this study. Significant seeding date X year interactions occurred due to changes in environmental conditions at each repeated seeding date. This indicates that while certain seeding dates during the year can be expected to provide good grass establishment because of cooler temperatures and more precipitation, failures can also occur at any seeding date when the expected favorable weather conditions fail to materialize. Stands were successful when the stems m-2 were equal to or greater than the stems expected from 11 plants m-2. Successful stands occurred 64, 58, 61, 52, and 45% of the time for smooth bromegrass (Bromus inermis Leyss., 'Lincoln'), western wheatgrass [Agropyron smithii Rydb., 'Rodan'; syn.=Pascopyron smithii (Rydb.) Love], crested wheatgrass [Agropyron desertorum (Filch.) Schult., 'Nordan'], sideoats grama [Bouteloua curtipendula (Michx.) Torr., 'Pierre'], and blue grama (Bouteloua gracilis (El. B. K.) Lag ex Steud., native collection], respectively. The significant seeding date X year interaction indicated established seedling stems m-2 varied greatly at the same seeding date in different years. This interaction explains why individuals favor different seeding dates based on their past experience. Successful seeding dates are summarized, but failures can occur at any specific date in a given year.