Giving ground a break – resting, green manure, sterilisation

I suppose this is for Keith in particular and all Dafnetters in general.
 
I have been taking an interest in posts about things such as mustard and crops for sterilisation.
 
In agriculture growers can give land a break from growing the same crop year upon year. 
The idea being that diseases and to a lesser extent weeds will have built up and something needs to be done.
Either a cleaning crop is grown or fertiliser and chemicals are increased to overcome problems.
 
Options are;
change crop – the basis of rotation, or a break crop for a year or two,
green manure – a fast growing crop is dug/ploughed in to give organic matter and/or nutrients.
 
A catch crop – rapidly maturing crop in between main crops is not quite the same thing, but may be useful,
for example, anyone tried growing lettuce in the daff plot.
 
I’m not sure about the meaning of sterilisation.
Does it mean any of the above, or has anyone found that unwanted diseases/organisms can be directly damaged, by say mustard?
 
George Norris  Scotland