I've recently read Tagari Publications-published 'The Power of Duck' and the author-published 'The One Duck Revolution'.
Both are by Takao Furuno, and both are about integrating ducks and rice culture, and about expanding this integration to include azolla and loaches (the fish). Dr. Furuno has trialed these approaches extensively.
'The Power of Duck' is fun to read; 'The One Duck Revolution' is a bit more academic.
'The Power of Duck' has detailed instructions with timing and amounts used.
https://tagaripublications.com/product/the-power-of-duck-integrated-rice-and-duck-farming/
https://www.lulu.com/shop/takao-furuno/the-one-duck-revolution/paperback/product-1ynvekyj.html
I'd love to learn what Dr. Furuno thinks of seed ball sowing of rice.
Do others agree that Dr. Takao Furuno is a permaculture artisan?