Q.exremely low nitrogen in soil
I have been putting in partially composted compost in my flower bed and vegetable garden and over the past few years have noticed some plants are not growing well. I just discovered that I probably have been depleting the nitrogen by putting this compost in. I tested it with a kit from Canadian Tire. The P and K are moderate but the nitrogen measures pretty well zero (the shade of pink determines the amount of nitrogen, dark being high, and it is completely clear, meaning little nitrogen). What is the best way to replace the nitrogen? I have put some composted cow manure in/on, but I suspect I need more than this. I have read that blood meal and alfalfa are good. There is a product called Scott’s Turf-Building Root-trients (27-0-5) which contains alfalfa but these are granules for grass. What do you suggest?

Certified GKH Gardening Expert
There are quite a few ways that you can go about correcting this issue, organic and synthetic. This article will go over your options: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/nitrogen-plant-fertilizer.htm