Video: Bumper Crops: Cover Crops and Water Quality"A cover crop can physically protect the soil from powerful raindrops that will dislodge the soil and make it easier to erode off of our field. So of course our organic matter and our P and K move with that, and that's a surface water pollutant. From an AG water quality standpoint, is there a gold standard cover crop? I think rye is a good starter crop. It's not fun and exciting, but it does the job. It fits well into corn and soybean systems, because you can plant it so late and even if it doesn't germinate in the fall, we do tend to see spring growth in February when we get those warmer days. It's a great scavenger of nutrients, so it's going to take that nitrate in the soil and put it in an organic form which is relatively safe."