Look up buck monster. It is some really good stuff. It's a mineral. Around $20 for a 2.5 gallon bucket. We've had deer on ours that evening after putting it out in the morning. I'm also still getting visits to a spot I put some out at almost a year ago.
I do salt as soon as turkey season comes in. This year, I planted sweet english peas and speckled butter beans for summer plots. Deer love those young tender beans.