Sustainability is a whole other subject
There is no goal or measure of sustainability applied as a requirement for organic certification here in Canada at least. Most organic growers rely on some sort of off-farm inputs, and even if those inputs are all on-farm sourced, there is nothing sustainable about depleting resources on one part of your land to benefit another part of your land. There is also nothing sustainable about using farm diesel to run your equipment, or the mining and energy used to create that same equipment. The only 100% sustainable agriculture I've witnessed in real life was the Ifugao tribe in the Northern Philippines mountains who have been growing on the same rice terraces for literally 1000's of years without any external inputs whatsoever. There they rotate terraces between growing fish and rice, and that apart from the native food plants they grow along the terrace edges comprises the majority of their diet.
Organic methods can result in better or worse sustainability than growing conventionally with chemicals. I would say though that striving to lower environmental impact and reintroduce carbon back into our soils is definitely encouraged among the organic farming community around here, and organic methods are seen as one route to achieving that.
