Here on the homestead we use buckwheat as a cover crop, and where we are resting a bed for the year. The way we use it is simply a chop and drop. It is then tilled into the soil to return the nutrients that it has collected. Fun fact, buckwheat is not in the grass family it is actually closer to rhubarb.
The planting of this cover crop is incredibly easy. There are many sites with detailed instructions on how to space it and how deep to cover it under. It has been our experience that none of that is really needed. Simply cast the seed out like you would grass seed by hand, and rough up the area with a lawn rake. Nature will do the rest.
While this plant can be taken to seed and harvested like grain that is not what we do. When the plant is mature and before it seeds (if you want) simply chop it down and leave it. After about a week of letting it sit, plow it under with a hoe. It is this cycle that builds up the soil and adds a wealth of organic matter.
The flowers from buckwheat are great for drawing in pollinators, and can be great to look at.