To pee or not to pee... that is the question
Since this seems to be a recurrent issue; and as there is considerable disagreement as to whether to pee on your lemons or not, I will take this opportunity to add my opinions (I hesitate to call it wisdom)
First peeing on lemons is a long held folk wisdom for making them prosper. To examine the issue scientifically, human urine contains urea (nitrogen) and is pH 6, so it tend to acidify the soil...both good for lemons; the downside is it may contain some semi-toxic salts; but assuming the lemon gets regular watering, not a real problem. Some people use a little vinegar to acidify the soil (acidifying increases the uptake of minerals); as long as the vinegar is apple cider vinegar, white vinegar, or wine vinegar it basically provides acetic acid without any sugars which could enduce mold or attract ants... Note, it is the methodology of producing the above vinegars that results in zero residual sugar.
Commercially, i.e. in field crop lemons, we more commonly use phosphoric acid for several reasons... the addition of phosphorous to encourage blooms; we can put it in the drip irrigation system; and it kills the rats that chew the drip irrigation tubing looking for water.
Another factor, for me.. I don't have enough people to pee on 7,000 trees every day; but I do encourage workers to do so when they wish. As a final warning, DO NOT let your dog pee on your lemon; it will burn young trees badly; cats are less damaging, but still unwise to allow it.
And that is about all I have to say on the subject.