A Rapid-Test for Biochar Effects on Seed Germination.

Biochar is being globally evaluated as an 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 rapid tests to determine biochar types most effective to improve soil characteristics amenable for higher crop yields. Seed germination is a critical parameter for plant establishment and may be a rapid indicator of biochar quality. We adapted Oregon State University Seed Laboratory procedures to develop a “rapid-test” for screening the effects of biochar on seed germination. For this study the soils were amended with 1% biochar by weight. We used 11.0 cm square 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 pattern), and covering with 15 g of the soil-biochar mixtures. Two South Carolina Coastal Plain soils, the Norfolk (Fine-loamy, kaolinitic, thermic Typic Kandiudult) and Coxville (Fine, kaolinitic, thermic Typic Paleaquults), were used. 18 biochars were evaluated 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.  Germination of cabbage, cucumber, onion, ryegrass and tomato were used to evaluate the effects of soils and soils amended with biochar. Preliminary results indicated differences in seed germination due to soil type and possibly soil x biochar feedstock interactions. Other measurements including shoot dry weight and pH of the soil-biochar mixtures will be evaluated. Additional research will be conducted to determine optimal biochar amendment rates, and the amount of soil-biochar mixture for optimal germination responses. This test method can also be used for a rapid evaluation of other soil amendments/treatments in addition to biochar on seed germination.