The role of diversity is critical to maintaining a well-functioning and stable agriculture. Where many different types of organisms coexist, there are fewer disease, insect, and nematode problems. There is more competition for food and a greater possibility that many types of predators will be found. This means that no single pest organism will be able to reach a population high enough to cause a major decrease in crop yield. We can promote a diversity of plant species growing on the land by using cover crops, intercropping, and crop rotations. However, don’t forget that diversity below the soil surface is as important as diversity above ground. Growing cover crops and using crop rotations help maintain the diversity below ground, but adding manures and composts and making sure that crop residues are returned to the soil are also critical for promoting soil organism diversity.