just as an example a lot of organic farms use composted manure to add Nitrogen but it also has very high levels of Phosphorus. You do this year after year and the Phosphorus will build up to levels that are toxic to the environment. Ideally, you would use the manure to get the right levels of Phosphorus and make up for the lack of Nitrogen with something else.
Just my understanding I could very well be wrong but basically just because its organic doesn’t mean too much of it doesn’t cause issues