Lowenfels also has a book on cannabis, it’s tailored towards autoflower varieties but useful non the less.
Theres several great threads right here on OG that are an excellent resource for organic approaches. But 2 that immediately come to mind are
CrunchBerries’Probiotic SIP Thread - Overgrow.com CrunchBerries’Probiotic SIP Thread
BeagleZ’ COPA Cabana - Overgrow.com BeagleZ' COPA Cabana