Tractor Uses a Soil-Ripping Shank (image) University of California - Berkeley Share Print E-Mail Caption A tractor uses a soil-ripping shank to loosen and mix soil in typical California farmland. In some parts of California, the soil was formed over hundreds of thousands of years before being transformed by agriculture. Credit (Photo by Ronald Amundson) Usage Restrictions The image may be redistributed and used with coverage of the news story. Not for commercial or other purposes. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.