Vetch Cover Crop (IMAGE) Washington State University Caption Farmers use cover crops like hairy vetch mixed with triticale or rye grass to supply organic matter to soil and make nitrogen available to plants. Credit Sylvia Kantor/WSU Usage Restrictions None License Licensed content 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.