Hairy Vetch is a ground cover crop and is a legume:
Hairy vetch PDF file
Hairy vetch is a winter hardy, annual legume. It is one of the best nitrogen-fixers and is reported to be more efficient at nitrogen fixation than peas. This makes it useful in vegetable crop rotations. Since it is slow to establish, it is usually sown with a nurse crop. Once established, it is good at weed suppression and soil conditioning.
Prepare a well-drained seedbed free of weeds and clumps of soil. Hairy vetch performs poorly on compacted soils.
It has high phosphorus and potassium requirements. Test soil for available phosphorus 40 lb/ac and potassium 120 lb/ac.
Hairy vetch will tolerate a wide range of pH.
Drill 15-20 lb/ac. Drilling is preferred for uniformity.
Broadcast 25-40 lb/ac.
When seeding with a winter rye nurse crop, sow 20-30 lb/ac hairy vetch and 70 lb/ac winter rye.
When seeding with an oats nurse crop in late summer, sow 40 lb/ac vetch and 80 lb/ac oats.