I read that some plants that develop a strong deep tap root quickly can
be used to help to break up compacted soil. I am going to be
rehabilitating a cow pasture and I need all the help that I can get in
this repect.

I would like something that grows quickly from seed, that is strictly an
annual or can be easily contolled otherwise so that it can be removed
when it has done its job. If it was a legume and could be left as a
green manure also that would be a bonus. I am in a warm temperate area
where we are into autumn, you can expect the occasional frost during
winter but no snow, the rainfall is around 1100mm PA and the soil is
rich clay-loam river bottom. Any suggestions?

David