Assessment of Native Warm Season Grasses for Post-Mining Reclamation.

The Red Hills Mine (RHM), located in Ackerman, MS, is an operating large-scale open-pit surface strip mine for lignite. Reclamation practices traditionally use browntop millet [Urochloa ramosa L.] and bermudagrass [Cynodon dactylon (L.) Pers.; BG] for quick emergence and soil stabilization. This objective of this study is to evaluate growth, yield, and forage nutritive values of native warm season grasses (NWSGs) compared to BG as a hay crop to meet the definition of prime farmland. A series of plots were established within a 6.0 ha reclamation field at RHM. Species tested consisted of big bluestem [Andropogon gerardii Vitman; BBS], little bluestem [Schizachyrium scoparium (Michx.) Nash; LBS], indiangrass [Sorghastrum nutans (L.) Nash; IG], upland switchgrass [Panicum virgatum L.; USWG], and BG, which were established in the summers of 2015 and 2016. Prior to harvests in 2017 and 2018, each plot was divided into a 1-cut and 2-cut system. Tiller counts in 2017 showed differences due to replications at the two-week and four-week counts. Tiller counts in 2018 showed BBS and LBS produced the greatest number of tillers, and the number of tillers were greater with supplemental nitrogen fertilizer application. Native warm season grasses produced greater yields than BG between 2017 and 2018. The greatest yields were produced in 2017 (with and without supplemental nitrogen), which is suspected to be due to greater rainfall totals than in 2018. Little bluestem out-yielded BG in both years under the 1-cut and 2-cut system. Mineral concentrations were in sufficient quantities leading to the 2017 season, while they were in decline during the 2018 season. This decline is suspected to be due to the difference in rainfall between years. Based on the results of this study, NWSGs qualify as a hay crop for prime farmland, which is only defined by yield, not forage nutritive value.