Collect Soil Samples (image) American Society of Agronomy Share Print E-Mail Caption Researchers collect soil samples from a crimped -- or flattened -- cover crop plot. Farmers can use cover crops to choke weeds and retain soil fertility. Credit Photo credit Kerry Clark. Usage Restrictions Please use with story only. 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.