I was in a field this week where a summer cover crop was planted about a week after corn was harvested. The grower planted quickly to avoid giving the weeds a chance to grow up once the corn was gone. A mixture of sorghum-sudangrass, sunflowers, daikon radish, and clay peas was planted and it grew up quite well considering how dry the late summer and fall have been.
The cold weather has already killed the sorghum-sudangrass and it has the sunflowers on the way out. The residue will be rolled down later in the winter when the next crop, field peas, is planted.
The cover crop did a good job of suppressing weeds. This field has been in continuous cash crop/cover crop rotation for 3 years and herbicide use has been greatly reduced over that same time. There weren’t any summer weeds to be found in the field. There were a few winter weeds (henbit and cutleaf evening primrose) coming up in some of the bare spots, though we would expect to see those smothered once the residue is rolled.
The daikon radishes have done a great job of opening up pore spaces in the soil. Water infiltration has greatly improved since this field has been in continuous cash crop/cover crop rotation.
The sorghum-sudangrass also has a pretty good root system. They are going down about 6 inches and loosening the soil.
As you could see from the first two pictures, there is a lot of biomass in this field. Much of the sorghum-sudangrass was waist high. This is going to provide a lot of organic matter and produce a good mulch layer that will continue to suppress weeds.