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A Quick-Test for Biochar Effects on Seed Germination
Johnson, M., T. Shiroyama, D. Olszyk, AND J. Novak. A Quick-Test for Biochar Effects on Seed Germination. Soil Science of America Annual Meeting, Minneapolis, MN, November 15 - 18, 2015.
The EPA is interested in new uses for biochar, a charcoal-like material formed when organic “waste materials” are combusted (pyrolyzed) at high temperatures without oxygen. Biochar can increase plant growth by increasing soil water holding and nutrient exchange capacities. Biochar can also reduce the availability of heavy metals and pesticides which can be toxic to plants. Critical to high plant productivity and yield is successful seed germination. Thus, we developed a “quick-test” in order to have an early indicator of the effects of biochar on seed germination. The test which could be completed in a short period of time with a minimal amount of expense and space, using small plastic containers and a vacuum method to rapidly and uniformly put seeds in each container. We evaluated this test using five crops: cabbage, cucumber, onion, ryegrass and tomato; two soils from South Carolina, and 18 different biochars (6 feedstocks made at each of 3 temperatures). The test successfully indicated that different soils and biochar x soil combinations can alter seed germination rates, with results available approximately 14-18 days after planting. Thus, we have developed a simple, efficient, and repeatable seed germination test. This test can be used for a rapid evaluation of the usefulness of specific biochars as tools to address important regional EPA goals such as: improving crop productivity on poor soils while using less water-pollution causing fertilizer, and the reestablishment of vegetation at superfund sites.
Biochar is being globally evaluated as a soil amendment to improve soil characteristics (e.g. soil water holding, nutrient exchange, microbiology, pesticides and chemical availability) to increase crop yields. Unfortunately, there are no quick tests to determine what biochar types are most effective at improving soil characteristics amenable for higher crop yields. Seed germination is a critical parameter for plant establishment and may be a quick indicator of biochar quality. We adapted Oregon State University Seed Laboratory procedures to develop a “quick-test” for screening the effects of biochar on seed germination. We used 11.0 cm rectangular x 3.5 cm deep containers fitted with blotter paper. The paper was premoistened with reverse-osmosis water, followed by placement of seeds (25 in a uniform 5 x 5 vacuum-assisted pattern, and biochar mixtures). A Norfolk and Coxville soil series from South Carolina were used. A total of 18 biochars were evaluated that were produced from 6 feedstocks (pine chips, poultry litter, swine solids, switchgrass, and two blends of pine chips and poultry litter); with biochar from each feedstock made by pyrolysis at 350, 500 and 700 ̊ C. Crops were cabbage, cucumber, onion, ryegrass and tomato. Preliminary results from the test indicated differences in seed germination due to soil type and possibly soil x biochar feedstock interactions. Other measurements including shoot dry weight per plate and pH of the soil+ biochar mixtures will be evaluated. Additional research will be conducted to determine biochar %, and amount of soil plus biochar for optimal germination responses. The test can also be used for a rapid evaluation of the effects of soils, and other soil treatments in addition to biochar such as pesticides and toxic materials, seed germination, and seed-mycorrhizal fungi relationships.