Biochar is being evaluated as an amendment to improve soil characteristics to increase crop yields, revitalize degraded soils and facilitate the establishment of plant cover. Unfortunately, there are few rapid tests to determine potential effects of biochar on soil and associated plant responses. Seed germination (emergence of hypocotyl) is a critical parameter for plant establishment and may be a rapid indicator of biochar effects. We adapted Oregon State University Seed Laboratory procedures to develop a “rapid-test” to screen for effects of biochar on seed germination and soil characteristics. Soils were amended with 1% biochar by weight and placed in 11.0 cm square x 3.5 cm deep containers fitted with premoistened blotter paper. Seeds were placed in a uniform 5 x 5 pattern and covered with 15 g of the soil-biochar mixtures. Two South Carolina Coastal Plain soils, the Norfolk (Fine-loamy, kaolinitic, thermic Typic Kandiudults) and Coxville (Fine, kaolinitic, thermic Typic Paleaquults), were used. Eighteen biochars were evaluated produced from 6 feedstocks [pine chips (PC), poultry litter (PL), swine solids (SS), switchgrass (SG); and two blends of PC and PL, 50% PC/50% PL (55), and 80% PC/20% PL (82). For each feedstock biochars were made by pyrolysis at 350, 500 and 700°C for 1-2 hours. Percent germination and shoot dry weight were evaluated for cabbage, carrot, cucumber, lettuce, oat, onion, perennial ryegrass and tomato. Soil pH, electrical conductivity (EC) and extractable phosphorus (EP), factors which can affect seed germination and early seedling growth, were determined after plant harvests. Germination primarily was affected by soil type with few biochar effects. Shoot dry weight was increased for carrot, lettuce, oat and tomato; primarily with biochars containing PL. Soil pH and EC increased with PL, SS, 55 and most 82 treatments across soil types and plant species. Soil EP increased substantially with SS and PL and to a lesser extent with 55 and 82 for both soils across species, and with SG pyrolyzed at 550 and 750°C soil for the Norfolk soil across species. Thus, this rapid-test method can be an early indicator of the effects of biochar on seed germination and important soil health characteristics which can be affected by biochar and effect seed germination.

This dataset is associated with the following publication: Olszyk, D.M., T. Shiroyama, J.M. Novak, and M.G. Johnson. A Rapid-Test for Screening Biochar Effects on Seed Germination. Communications in Soil Science and Plant Analysis. Taylor & Francis Group, London, UK, 49(16): 2025-2041, (2018).