Rapeseed is a fall seeded brassica that farmers are using for nutrient scavenging.
Dwarf essex rapeseed
Rapeseed made it's way into the cover crop world a few years ago as an inexpensive alternative to radish.
As you can see in the picture, they have very different root systems. The rapeseed typically survive longer into the winter and some plants will even overwinter.
Rape produces a lot of top growth as well, so if you're looking for some brassica forage, this is a real opportunity.
For planting guidelines, see our Seeding Information Guide.