Green fertilizer (IMAGE) Iowa State University Caption Vignesh Kumar Thoomatti Haridass, a postdoctoral research associate working with Iowa State's Liang Dong, installs soil and stalk nitrate sensors within a cornfield. Credit Photo by Liang Dong/Iowa State University. Usage Restrictions None License Original 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.