One thing that makes no sense to me, is the worry that the necessary microbes are not available to do their job, in any soil anywhere that hasn't been poisoned. I have googled and read about Trichoderma harzanium natural habitat etc. and it is basically found everywhere, worldwide. It is found in every 'organic' garden compost (meaning no poisons added). Sure in a farmer's field which has been sprayed with this or that chemical, they might be deficient. However, whenever you add a good compost you are adding these beneficial microbes to the soil.
As regards the guanos, they sure are amazing and it's too bad I can't access some local stuff from the seabird island areas for example. Because the price of them here is... strictly in the realm of luxuries, to me. I know a lot of that price is shipping - in fact being so far off the beaten track up north here, it is always obvious that a big chunk of the "imports" price is for the fuel involved in carrying them. So exotic materials really don't make sense for me.
I haven't seen fish meal on the market here, surprisingly enough. Caplin is the traditional fertilizer here - applied fresh when you trench your potatoes, not a whisker of it remains by the time they are dug. These little fish break down really fast. The oilier the fish the longer it takes to break down in the soil. Things like mackerel and salmon, can be a long time in the ground and release nutrients over a span of years here rather than months. And partly that is due to the temperatures being cool here as well, your mileage surely varies depending on the environment where the fish meal is used too, I would think.
In my greenhouse in a normal summer, chopped up kelp in container soil is completely consumed before the season is over. In the garden it's not the case. I grew garlic in a kelp/lasagna bed one year, and the deepest layer of kelp was still intact when I dug that bed in the fall. Soil temperature is a big issue for us.
Not so much for you lot.
