Our organic guru just told us to put some epsom salts on the yellow corn we have in certain areas........the the epsom salt will help the corn take up N.

Appears that the epsom salts (magnesium sulfate) would provide magnesium to the plant via foliar feeding.........how does the magnesium aid in the uptake of N?  

Increases the flow of water in the roots??? ............and therefore the N that would be in the root area?

Appears that would be good for the soybeans also........water uptake cannot be bad????? 

Why wouldn't we do this as a matter of routine, ie regular component of the spraying.........surely wouln't provide too much magnesium if the plant was already sufficient in Mg???? 

Thanks.