How much nitrogen is too much in woodchips?

I have a few deep arborist mulch beds that are on their second season. Last year I grew potatoes and tomatoes to get them started and my yield was pretty bad. 2:1 roughly for the potatoes. Better than nothing of course. Last fall I topped up the mulch. I’ve started planting again in the spring. Since I had low fertility last year and I know it takes about 3yrs to get a woodchip bed really going I’ve been saving all my urine and spreading it diluted over the beds. Is there some limit to how much I should put on the bed or should I just go at it with abandon?

I would add some materials besides just urine, to get a larger variety of microbes in there.  Sheet composting with weeds, kitchen scraps, lawn clippings, etc will help.  The main concern with urine is the high salt content.