What is the Best Way to Add Nitrogen to Soil?
The best way to add nitrogen to soil is to apply a fertilizer with high nitrogen. You can use either an organic fertilizer or non-organic fertilizer depending on what your goals are. Non-organic fertilizers will be quick acting while organic fertilizers take more time.
Additional information will help determine which fertilizer type to use.
How Much Nitrogen Do You Need?
In order to know exactly how much nitrogen the soil needs, you would need to have the soil tested. Any local nursery can do soil testing. This will give you the soil situation and then you can determine how much nitrogen you need to add.
You can also buy a soil testing kit and do it yourself. The testing kits cost from $35 to $50. You can buy them online.
Another consideration is the type of plants you will be growing or already have. Some plants need more nitrogen than others. Big leafy plants need more nitrogen like tomato plants.
If you have poor soil like sand or clay, then you will need lots of nitrogen. If your soil on the other hand is rich with lots of organic material then you might not need much or any nitrogen.
If you need a lot of nitrogen then look at Urea 46-0-0, ammonium nitrate 34-0-0, ammonium sulfate 21-0-0 or a 20-10-10 fertilizer. These contain the most nitrogen.
How Fast Does the Soil Need the Nitrogen?
Another consideration when thinking about adding nitrogen to soil is how fast do you need the nitrogen to be available. Do you need it right away or in 2-3 months? Or both?
If you need more nitrogen right now, then you will need to use a non-organic or synthetic fertilizer with high nitrogen. Synthetic fertilizers can release nitrogen in a day or 2. Organic fertilizers take a few months to make nitrogen available and release it in smaller amounts. Bat Guano probably has the highest amount of nitrogen out of the organic fertilizers. It has about 11-13% nitrogen. Synthetic fertilizers can contain up to 46% nitrogen. Urea fertilizer has the highest amount of nitrogen and has a NPK of 46-0-0.
So, if you need nitrogen fast then use a non-organic fertilizer. Urea has the highest amount of nitrogen at 46% while ammonium nitrate comes in 2nd at 34%. Or you can use something like a 20-10-10 fertilizer for a smaller amount of nitrogen. These fertilizers will release the nitrogen in a few days.
If you have existing plants that need nitrogen fast then this is the way to go. If you have a lawn that needs to green up tomorrow then use one of these fertilizers. It will green up in a few days. The transformation is pretty amazing.
If the nitrogen need is not immediate then you can condition the soil with an amendment like compost or steer manure or a commercial garden soil. Mix any of these into the soil or use it straight as the soil. It will provide nitrogen slowly over 4-6 months.
Organic Nitrogen Fertilizers
Organic fertilizers have much smaller amounts of nitrogen but it is released over a long period of time like months. The highest nitrogen organic fertilizer is bat guano which has about 11% nitrogen. Compost has about 2-5% nitrogen. However it will release nitrogen for 6 months or longer.
If you are starting a garden and the soil needs nitrogen then prepare it beforehand. My native soil is clay and does not have any nitrogen, so I have to prepare the soil before growing anything. I mix my native soil with compost in a 1:1 ratio or 1 part soil and 1 part compost. This produces a rich organic matrix that not only contains nitrogen but will also retain water, promote aeration and resist compaction or turning into hard rock when dry. Plant roots like soft soil to grow in without obstacles.
I start preparing my gardens a few months before the growing season. This gives the soil time to initialize the ecosystem. Microbes and bacteria will grow and start to break down the compost into useful nutrients. I prep gardens by tilling the soil or loosening it up and then mixing compost with it.
A 50/50 mix of native soil and a good compost will produce a rich soil that is perfect for most plants. You won’t need to fertilizer for several months if at all during the growing season. When you do need to fertilize, just add a good 3″ thick layer of compost on top of the soil. It will decompose and release nutrients into the soil and also reduce water evaporation. You’ll need to water less often and plants will have more time to absorb the water.
Here are some products you can use to organically fertilize soil with nitrogen.
- Composted steer or cow manure
- Commercial Garden Soil like Kellogg’s
- Soil Conditioners like Kellogg’s N-Rich
- Bat Guano
- Blood Meal
- Worm Castings
Non-organic Nitrogen Fertilizers
Non-organic fertilizers can release large amounts of nitrogen in a day or 2. They are pretty amazing when you see the results after a few days. There are also “slow release” synthetic fertilizers available.
The synthetic fertilizer with the highest amount of nitrogen is urea with 46%. Ammonium nitrate is the 2nd highest with 34% nitrogen and then ammonium sulfate with 21% nitrogen. Any of these can be spread over the top of the soil but it works best if it is mixed or tilled into the soil. This forces the nitrogen to stay in the soil and not escape into the atmosphere when it decomposes. Watering after fertilization will push the nitrogen into the soil where plant roots can absorb it easily.
Because synthetic fertilizers release nutrients quickly, you will need to fertilize every 4-6 weeks to maintain a good supply of nitrogen. Another option is to mix a slow release form of fertilizer with a fast release. You get the best of both worlds.
You can use synthetic or non-organic fertilizers before you plant or after you have already planted. It will increase the growth rate and size of plants quickly. Leaf coloration will dramatically change from light green or yellow to dark, emerald green.
Synthetic fertilizers come in granule form and are easy to apply and store. Follow the directions when applying to avoid harming plants. Too much fertilizer can burn plants and possibly kill them. Urea and ammonium nitrate go along way in gardens where you only use a cup or two for 100 square feet. A 10 or 25 lb bag will last years depending on how large your garden is. It’s pretty cheap at a few dollars per pound.
Here are some non-organic fertilizers that will provide a lot of nitrogen to soil.
- Urea fertilizer
- Sulfur-coated urea
- Ammonium nitrate
- Ammonium sulfate
- 20-10-10 fertilizer
- 15-10-10 fertilizer
- Calcium nitrate
- Potassium nitrate
- 10-10-10 fertilizer
I like to use both types of nitrogen fertilizers, organic and non-organic. In my garden I like to use mostly organic fertilizers but occasionally use urea to spur some growth and produce darker green leaves.
Organic fertilizers work great in gardens as long as you have time to prep the soil before planting. The soil/compost mix or all compost soils work great for vegetable and flower gardens. Plenty of nitrogen will be available for any type plants from tomatoes to lettuce and corn too. Most compost and commercial garden soils cost about $9 per 3 cubic foot bags. 1 bag is enough to condition a 4″ x 8″ box garden.
When it comes to greening up my lawn, I stick with synthetic fertilizers like Urea or ammonium nitrate. It’s cheap, easy to apply and works like magic. Trying to use compost on the entire lawn is not feasible since the grass is already growing which makes it impossible to mix the compost with the soil. Applying compost on top of the grass is not ideal.
I like to mix urea fertilizer with water and then spray the lawn. The dissolved urea penetrates the soil and fertilizes quickly. The grass greens up overnight and grows much faster for weeks.