Our urine is sterile, and it is therefore safe to use as a direct foliar spray on plants and trees with a 10% dilution (10% urine, 90% water). If you have a vegetable garden, you can add liquid gold, at the 10%/90% water ratio, in a backpack sprayer and simply spray your plants every few weeks. The alternative, that seems to work just as well for seedlings, is to use it just like any fertilizer you add to the water for watering the plants (again, 10% dilution, and I kind of eyeball this and don’t measure it exactly.) Add this in your garden how you would other compost teas–usually as a side dressing.
You can collect urine in any way you like–in an elaborate system, like at the ecovillage, every guest’s urine is diverted and used on extensive gardening systems each time they visit the urinal. But you can also collect urine in the most simple system, like a wide-mouth canning jar. It doesn’t necessarily take a long time to collect enough to be used for plants (indoor, outdoor, or seedlings)–think a few hours of collection for weekly watering of indoor plants. And you don’t need to use the liquid gold every week–I usually use it every 2 weeks and my plants are very happy. You do want to use the liquid gold fairly quickly, as it starts to turn to ammonia and develops a stronger smell.
After returning home from the Ecovillage, and especially with my seed starting this year, I started using liquid gold even with my small potted plants and house plants. It was incredible to see the difference—urine is almost pure nitrogen, and that is a resource indeed! My bay plant, which was suffering some aphid damage, quickly sprouted a ton of new growth. My baby tomato and pepper plants for my garden plot and assortment of herbs are twice as big as they should be at this point in their growth! Its really amazing stuff (and I am going to do some scientific experimentation on it in my community garden plot this summer and report back). You can read more about urine and how to use it as fertilizer in a book called Liquid Gold.