Reading up on these alternate soil amendments is pretty fascinating stuff, sounds like a great way to avoid damaging the waterways while enriching the soils.
Terra Preta is “Black Earth” and is composed of charred organic material, and supposedly regenerates itself based on the microbial/bacterial/fungal activity , providing a supply of fertile earth in the other wise nutrient poor amazon rain forest.
Mycorrhiza are generally beneficial fungi are symbiotic and provide plant roots with miniscule hyphae that transport moisture to the plant in exchange for sugars.. Interesting stuff.