Germination of Blue Wildrye in biochar treated mining impacted soils

Stabilization of mine sites with vegetation is an important management strategy to reduce metal movement off-site.  Plant growth, however, is often hampered by poor soil conditions.  Biochar is a novel soil amendment that may improve soil health conditions and improve plant growth.  Biochar properties can vary widely, so it is prudent to pre-test the efficacy of these and other amendments on seed germination and plant growth.  Here we report on a rapid (1-2 weeks) germination study using soil from the abandoned Formosa Mine, a former copper and zinc mine near Riddle, OR.  We used Miscanthus (Miscanthus x giganteus) biochar as a soil amendment along with lime and fertilizer.  The study was established using a full factorial design with 4 replicates.  Dry, sieved (≤ 2 mm) Formosa soil (pH ≤ 2.6) was amended with biochar at 0, 1, 2.5 and 5% by weight.  Twenty-five seeds of blue wildrye (Elymus glaucus cv. 'Elkton') were placed on moistened blotter paper in clear plastic germination boxes and 15 g of amended and unamended soil (control) was used to cover the seeds.  The soil and seeds were wetted and the boxes placed in a growth chamber.  Information on seed germination was collected daily, along with soil characteristics (e.g., pH, EC, etc.) at the end of the study.  In soils without amendment, there was no seed germination.  Soil pH increased in the biochar and lime treated soils.  Similarly, germination rates also increased with biochar amendment (without lime), but were less than 20%.  Liming was the key factor to increasing germination rates to more than 90%, while this biochar-type had a secondary role (e.g., metal sorption).  Our preliminary results suggest adjusting soil pH to conditions suitable for plant growth will improve seed germination and growth.  However, higher rates of biochar amendment may also increase germination rates.