I totally agree with Adam that "Excesses are more problematic than deficiencies, which is why we need to amend intelligently with targeted minerals."
As I think Steve Solomon (author of the Intelligent Gardener amongst other
books) suggests, dealing with excesses is about "as easy as getting too much salt out of the stew" .
Actually likely harder--adding lots of potatoes and some sugar can ofttimes redeem an over-salted soup/stew or casserole.
As to Boron issues--you often see hollow stems in commercial broccoli in the store, which I was taught was a clear sign off a boron deficiency, and I've observed it in both conventional and organic produce on offer, so interpret that to indicate a widespread nutrient deficiency with commercial produce.
I know when I did Graeme Sait's
course in 2009, he used a phrase: "Calcium is the trucker of all minerals and boron is the steering wheel." Also, there is a link on his site about the foliar
feed 'controversy', at
http://www.nutri-tech.com.au/blog/2009/02/seminar-field-day-boosting-avocados/
This article is mostly about Avocadoes and in a different climate, but the underlying principle remains the same--Boron is a very important
trace mineral.
For what it's worth, I'd actually rank Graeme at or maybe even above some of my
permaculture teachers in knowledge and passion for sharing it.
He has a company(in Australia) producing products more targeting existing farmers and growers looking to change for various reasons than smaller operations where permaculturists are more likely to be found.
He recently ran a course in Ontario, Canada too and is high demand internationally.
If anyone is interested in his work (I'm in no way connected, just grateful that he's working and teaching still) there is a good 20 minute TED talk of his at:
http://www.youtube.com/watch?v=8Q1VnwcpW7E
Humus.....human....humility
Food for thought
Maybe deserves a new/fresh
thread.
Edith