destruction of the soil

"Farmers in Asia have composted human manure for centuries, They've maintained the vitality of the soil that way:)"

Yes.  By farming that way, China had created 8 feet of topsoil over the centuries by using human waste.  With the advent of chemical fertilizers that they now use, they have destroyed that topsoil and now have to use chemicals in order to produce a crop!  

I used to watch in amazement (astonishment, or whatever) as I would see a Korean farmer with a bag of human fertilizer over his shoulder, grabbing a handful with his bare hand, then throw it on the ground and push it into the ground with his bare foot!  They built up an immunity to the diseases that is in the stuff, and quite frankly, I believe that garlic helped in their protection.  Harvard University has contracts with several different provinces in China and are doing research on eating habits in relation to illness.  China is unique in that one city may eat lots of garlic and onions while in a neighboring city those things are rejected as strange.  This is a long-term study and so far they have found that diets high in onions and garlic result in a significantly lower incidence of prostate cancer.  I remember that one, and think there were other advantages too.