I watched Modern Marvel history of fert this past week. After doing some research, it seems that ANY soil would benefit from the addition of Guano, and manure of some sort. I also like the idea of worm castings/poop. ( http://www.wormpower.net/worm-castings/index.php ). Is this something that a LAWN would benefit from or do you think my perennial/woody plants would be the best beneficiaries of this sort of thing? Would a thin (1/2") top coat of one of he above mentioned products be enough, say 1-2 times (spring and fall) a year? Thanks!