Nitrogen Nodules on Plant Roots (image) Washington State University Share Print E-Mail Caption Root nodules on hairy vetch store nitrogen captured from the air with help from Rhizobium bacteria. The stored nitrogen is released into the soil when the plant dies and decomposes in place. Credit Sylvia Kantor/WSU Usage Restrictions None 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.