POLAND: An ancient technique of plowing charred plants into the ground to improve the quality of soil may also trap greenhouse gases for thousands of years and forestall global warming, which is being caused by the emission of harmful green house gases, a team of scientists and experts working on this project, said on Friday. Heating plants such as farm waste or wood in airtight conditions produces a high-carbon substance called biochar, which can store the greenhouse gas carbon dioxide and enhance nutrients in the soil.