An Ag Lime test recommendation (like those the USDA gives) is usually to only amend soils for a single growing season. When I got an analysis per acre, I suggest multiplying that by 10 for longevity along with adding limestone rip-rap to all inflow channel areas as far upstream as practical. Ag lime tops out in raising pH at a very safe 8.2.
In a heavily pine tree filled watershed, the dropped needles are very acidic, so Ag Lime really can't be over-applied.
