I did a soil test and it says that I have lots of P and K but very little N.
What kind of fertilizer is best to use to replace the nitrogen in my soil?
It is almost time to plant, and I am already planning on using manure, probably a combination of sheep and cow. I compost and add that to the garden every year as well.
Depending on what has been put in it compost can have anywhere from very little to quite a lot of nitrogen. Dense materials like wood chips or straw have enough Carbon that they will bind any nitrogen in the mix. Other materials like grass clippings can be richer in Nitrogen.
Animal manure nutrients are heavily dependent on the animal's diet and how fresh it is. Fresher manure will tend to be higher in Ammonia-Nitrogen as that volatilizes quickly if it is not taken up by a plant or mixed into the soil.
In either case, you will be getting some amount of Phosphorous and Potassium by the simple nature of composts and manures. If you were looking at purchasing fertilizer, this question does a very good job of explaining how fertilizer labels work. If you're just looking for Nitrogen remember that the label for fertilizers are Nitrogen-Phosphorous-Potassium. Any fertilizer with a high number in the first position will be mostly Nitrogen. Be careful what you buy at the store though, I once almost bought a bag of lawn fertilizer that was labeled 24-0-0, then fortunately noticed it was Lawn Weed-and-Feed and contained enough herbicides to kill my garden dead.
All commercial products sold as fertilizers (and some compost and compost manure), both synthetic and organic, have a guaranteed analysis printed somewhere on the package. It's three numbers such as 9-1-3. These are the percent by weight of nitrogen, phosphorous and potassium (N-P-K) in the fertilizer. Since you don't need P or K look for a fertilizer with a high first number which indicates it has a higher percentage of nitrogen.
Your soil test report should have given you a recommendation for how much nitrogen to add. Something like 15 lbs of nitrogen per 1,000 square feet.
Once you've settled on which fertilizer to use, calculate the size of the area you will be applying fertilizer to in square feet. For example let's say your garden is 200 sq ft.
So let's say at 15lbs/1ksq ft over 200 sq ft... 3lbs of nitrogen would b e needed. (15lbs/1,000sqft * 200sqft).
Next you need to figure out how many lbs of fertilizer to deliver the 3lbs of nitrogen. Using the example above 9-1-3 example above 1lb of fertilizer contains .09lbs of nitrogen. To get three lbs of nitrogen from this fertilize you would need 33 1/3rd lbs of fertilizer. (3lbsN/9%).
If you're using multiple fertilizer determine how much N each one provides and make sure the total will deliver the amount of N you need.
Depends - if you are chemical fertilizer user, 45-0-0 urea might be an approach, or any other X-0-0 fertilizer, with application rate depending on "X"
For the more organically minded but not strict vegans, blood meal is one good high-nitrogen choice, as are various fish-derived fertilizers or "trash fish"/fish waste. They may be relatively expensive, and can smell not very nice.
Alfalfa meal is another possible choice, though it has relatively more P&K than the other two. Soybean meal and cottonseed meal are other possible choices. Soybean meal may be the most affordable option other than manure.
Chicken manure has relatively more nitrogen than most other manures (but that can sometimes be a problem of having too much.)
