They way I see it there are two kinds of "organic" growing. Well three if you include the organic growers that aren't really organic
every self-proclaimed organic grower I've ever met that grow in containers has at least a bottle of synthetic pH up/down in their nute cabinet...d'oh!
First there is the
input substitution approach which is what the vast majority of organic growers use. This system attempts to replicate conventional production systems, except using organic inputs rather than synthetic ones.
The other approach is known as
agroecology, and it attempts to challenge both the monoculture structure and dependence on off-grow inputs by utilizing regenerative systems that rely more on biodiversity and inputs available on-site...like sunshine or the nitrogen in the air.
Reusing "soil" is a great first step toward regenerative systems, but incorporate some biodiversity, too. Grow something else in that soil before you grow your next Cannabis crop in it
I recommend both a grass and a legume. Grasses are excellent at scavenging available nitrogen and provide aeriation to your soil/compost pile while legumes can add nitrogen to your soil (inoculate the seeds for max N fixation). I use different combinations for the used soil from each of my crops. Be sure to terminate these crops before they set seed and compost everything together.
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Only because some organic farmers were using manure improperly...that shit needs to compost first! But E. coli produce recalls in the US
peaked in 2014 and have dramatically decreased since then due in part to
safety regulations announced in 2015. While a few studies have found higher prevalence of E coli on produce from organic farms,
the vast majority have not found this to be the case.
By "hydro" I assume you mean conventional DWC or EAF systems? Because many (most?) organic Cannabis grows are also hydroponic systems, typically drip or hand applied. Even feeding teas is technically hydroponics. Hydroponics just means that inputs are being applied in a liquid form.