By accident I used 50% of gardenlime on a single plot,I planted a potatoe and watered it.It took about a minute to harvest the complete plant and get 23 Potatoes.
I have testet it with 100% gardenlime and it was fast..very very fast till I could harfest 39 potatoes from a single plant.

I did like it..but I guess its a bug and not a feature^^

Edit:
Ok,I testet with zuchini,tomatoes and peppers aswell.
Same result with all of them.
Tomatoes with 100% lime yield 62 Tomatoes from one plant within 20 seconds
Tomatoes with 200% lime yields 149!!! Tomatoes from one Plant within the same time.

It seems there is something that wants to prevent the player from using more than 100% lime on a single plot,but if I use only 95% and grab a new pack of lime I can just continue to use as much as I want.Stopped with 200% lime on a single plant since its a pain to find much more lime right now^^