To overseed, broadcast seed into an existing stand of other crops. For example, red clover is often overseeded into grain fields in the spring after the grain has become established. After the grain is harvested, the clover can continue growing for another season. Legumes can also be overseeded a few weeks before dieback of the main crop. This way, the canopy begins to open just as the legumes need more light.
Legumes combined with grains or grasses provide excellent green manures.
The legumes can be overseeded or broadcast with the grasses. After the green manure is turned under, the carbon in the grains or grasses will tie up some of the fixed nitrogen, preventing it from being leached. After trying a number of green manure combinations, I was most impressed by crimson clover mixed with annual ryegrass, and oats mixed with common vetch. Ideally, the legume seedbed is kept moist for several weeks after planting. Many legume seeds are close to the surface and take a couple of weeks to emerge.