Why do people add potassium nitrate to plant fertilisers?
Many plants have fungi that grow on their roots. The plant and the fungi are symbionts, meaning they coexist together to aid both organisms in survival. Fungi can “fix” nitrogen and I believe use potassium as well in their metabolic processes. As a byproduct, fungi give off vital nutritents that the plant roots can then absorb. So the potassium nitrate is actually aiding these fungi, not the plant itself. But its these fungi that can help the plant grow faster.
