Organic amendments direct grass population dynamics in a landfill prairie restoration

This study examined the effects of amendment application methods on the establishment and growth of prairie grass in a landfill remediation. Amendment treatments included three application rates [control, low (765 g m−2), and high (1530 g m−2)] of a wood chip amendment at two different application depths [surface-applied and incorporated]. Grass populations were monitored for 2 years after seeding to assess differences to seasonal precipitation patterns. Initially, total basal area (cm2 m−2) and tiller density (tillers m−2) were greater in the surface treatments, but seed burial may have reduced establishment in the incorporated treatments. The application rate required to improve the initial grass response differed by depth: the low rate was superior in the surface treatments, but when incorporated only the higher application rate improved establishment. Over the 2004 season, tiller density increased in the surface treatments, but not in the incorporated, following the seasonal drought. In contrast, the incorporated treatments experienced a smaller reduction in tillers during the more severe drought conditions of 2005. These results suggest that a moderate application rate of surface-applied amendment is sufficient for aiding the development of the grass portion of the restored community and the extra effort associated with incorporation is not justified.