Using Urine as a Foliar Fertilizer

During the Choosing Organic Fertilizer and Building Soil Fertility workshop at the 2012 Mother Earth News Fair the topic of using urine as a foliar fertilizer came up. A gentleman in the audience said that he had been using diluted urine as a fertilizer and had been producing prize winning crops with his method. This was intriguing to me, especially since I sometimes collect urine to add to the compost. He indicated that he saved urine during the winter, and then mixed with water to dilute and applied to his crops in the spring and summer.

Initially I planned to use the same approach, and begin collecting and storing urine at least a couple of months before I would need it. I was planning to look for a container to use for urine storage when we last visited the Lexington Container Company. As I gave it more thought, however, I determined that storing two months of urine would likely be overkill, at least for our relatively small garden. I produce a lot of urine, and even though I don't know the exact quantities, I'm confident in saying that collecting for two months would result in  excess of 20 gallons. Based on the suggested dilution ratio of 20:1, that would be enough to create 400 gallons of foliar spray, which I suspect is way more than we'd use. For this reason I've decided to use more of a real-time collection strategy.

I use a 4-gallon plastic jug for urine collection. It has a nice airtight lid, which seems to prevent the normal stale urine smell, which I understand is the result of  a reaction with oxygen. I haven't been collecting lately, but once the gardening season starts I will resume collecting urine. When I want to mix a foliar spray I will have fairly fresh urine available, and will then apply the rest to the compost. I will probably only use a dilution ration of 10:1, rather than the suggested 20:1, since my urine tends to be quite dilute anyway due to the large amount of water that I drink. I will buy a garden sprayer to use specifically for this purpose, and will mix the urine and water directly in the sprayer tank.

The suggested foliar feeding frequency that I've seen is twice per week, so that is likely the schedule that I will use. I plan to use the spray on peppers and tomatoes, at the very least, but will likely apply to other crops as well. I haven't decided yet if I'll apply to every plant, or leave some as a control in order to gauge the impact of the spray. Having a control would be idea, as would keeping detailed records, but I'm not sure how diligent I would be with record keeping.

Before beginning my experiment I should probably re-read Liquid Gold: The Lore and Logic of Using Urine to Grow Plants. I read it a few years ago, but could certainly use a refresher. I'll try to get to it before Spring, and do a book review once I do.