That’s really interesting Tom. I have considered the potassium link from a different perspective.

What slugs love the most is wilting leaves. A pile of freshly cut comfrey or potato haulms attracts slugs like nothing else. When we consider that potassium is responsible for turgidity in plants then plants low in potassium are less turgid, like freshly wilted leaves.

Perhaps manganese, the regulator of potassium, could help when applied at a crucial point. I read an article about the role of slugs in the natural environment and it was found that there presence greatly increased the manganese levels in the soil.

Copper, Iron, Potassium, Manganese, that’s a lot of points to join up.