How to Add Nitrogen to Your Garden Soil (9 Ways)
Sufficient nitrogen in soil is key for abundant harvests. Without enough, your plants may be stunted or have yellow leaves. But how do you add nitrogen to your garden soil? Keep reading to learn how to do this in the short run, and how to build healthy soil over time.
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Far too often, gardeners rely on chemical fertilizers to help their vegetables grow. While these chemical fertilizers give your plants a boost, they do so at the expense of healthy soil life.
The result is, each year your soil gets poorer and you become ever more reliant on buying those chemicals to keep your plants afloat.
This isn’t good for you or for your garden. The better way is to work with nature to build abundant soil over time.
And luckily, there are also some short and medium-term fixes to help you out as you work toward that long-term goal.
Testing your soil is a great way to know for sure if your garden soil is lacking nitrogen. Here are a couple tests that can be used to help you determine the nitrogen levels in your soil. The 1st is a professional test where you send in samples to a lab. The 2nd is a DIY test that you can complete at home. You can also reach out to your local master gardeners or conversation districts to find local options to get your soil tested.
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Techniques to add nitrogen to your garden soil while working with nature can be broken into 3 general categories:
- Instantly add nitrogen to your garden soil.
- Build nitrogen levels in your garden soil over time.
- Add nitrogen to your garden soil indirectly.
The 1st category offers quick ways to add nitrogen to your garden soil now if you notice signs of nitrogen deficiency in your plants. But the techniques covered by the 2nd and 3rd categories are all about adding nitrogen to your garden soil over time, to give you more abundant harvests with less work over the long haul.
Let’s dive into some of the quick techniques first.
But before we do, make sure to grab your free and easy-to-print cheat-sheet that covers one of the strategies featured here—growing plants in polycultures. This approach to growing your plants is key to building healthy, rich soil that results in abundant harvests while also reducing your pest issues.
Instantly Add Nitrogen to Your Garden Soil
Yellowing leaves and stunted growth can be a sign of nitrogen deficiency in your plants. When this happens, it might be time to give that plant a nitrogen boost.
But don’t reach for the chemical fertilizer. Here are some ways to give your plants a quick dose of this vital nutrient:
1. Blood Meal or Alfalfa Meal
One option to quickly add nitrogen to your garden soil is to use blood meal. Blood meal is dried animal blood that is left over from the butchering of animals.
It’s very rich in nitrogen, and, when added around your vegetables on the soil surface and then watered in, it can give your plants a nice boost.
But it can also attract animals to your garden. An alternative for anyone not comfortable with bloodmeal is alfalfa meal.
This is made from alfalfa. And while it doesn’t have as much nitrogen in it as bloodmeal, it’s a good alternative.
With either of these solutions, just make sure to follow the instructions on the packaging.
2. Diluted Human Urine
But there are also some free solutions to give your vegetables a nitrogen boost.
The first is to use diluted human urine. While this may seem distasteful to some, as long as the urine is from a healthy person, it is sterile.
Urine by itself will burn your vegetables, and it can have a high level of salt in it. Because of this, you need to dilute it with water—10:1 or even 20:1 for young plants. That means 10 or 20 times more water than urine.
Then just add it around the base of the plants that need a nitrogen boost.
3. Manure Tea
But another option is to use animal manure and make manure tea. This is a simple process that involves adding animal manure (don’t use cat or dog manure) to a bucket and then filling the bucket with water.
The resulting “tea” can then be further diluted and added around your vegetables to give them a nitrogen boost. The above link will give you more information about how to make manure tea.
Each of these methods will add nitrogen to your garden soil if you need a quick boost in the short run. But you also want to build nitrogen levels in your garden soil over time, so you don’t have to rely on the short-term methods.
Let’s look at these other techniques.
Build Nitrogen Levels in Your Garden Soil Over Time
When you’re still building your garden soil, you may need to use a quick method to give your vegetables a nitrogen boost.
But your goal in the long run should be to build the overall fertility of your soil so that your vegetables never need a nitrogen boost.
This can be done by ensuring you are building nice, deep, rich soil.
One way to do this is to add compost to your garden beds. But this isn’t an overnight source of nitrogen for your garden.
The compost will slowly release nitrogen (and other nutrients) to your plants over time. Plus, it will support and add life to your garden soil.
The result of adding compost to your soil is that levels of nutrient levels (including nitrogen) will slowly increase along with organic material.
Animal manure can also be added directly to your garden soil. But you’re likely to get better results by adding animal manure to your compost pile.
This will build your garden soil, resulting in an overall abundance of life—including great vegetable harvests! In the long run, this is fantastic!
But it’s not an overnight fix—it’s part of a long-term strategy to build rich soil.
5. Chop-and-Drop Mulch
As great as compost is for your garden, it does take time and effort to make. An alternative method is to compost in place in your garden. This can be done by practicing chop-and-drop, where you cut green and spent plants such as your vegetables and drop them directly on top of your garden soil.
You can add other plant material to the surface of your garden that you cut from other areas. This material will break down slowly in place. And over time, it will add nutrients to your soil, including nitrogen, while also supporting soil life.
But it will take time. Particularly because a portion of the nitrogen is lost to the air before the plants break down into soil. Creating compost is faster, but it takes more work.
6. Plant Nitrogen-Fixing Plants
Finally, you can also grow nitrogen-fixing plants in your garden. Beans and peas are common vegetables that fix nitrogen.
Though this is often touted as a strategy to add nitrogen to your garden, it’s more complicated than it seems.
While these vegetables do add nitrogen to the soil, they will use most of it to produce the seeds that you harvest. Some nitrogen will still be added to the soil, but you will need to cut these plants down as chop-and-drop before they flower and produce seed.
Obviously this isn’t ideal with your peas and beans! Some people get around this by growing cover crops.
With cover crops, you generally take a break from growing vegetables for harvest and instead grow a cover crop.
These cover crops are grown so they are killed before they reach maturity and use up the nitrogen. This can be done by planting them so the first hard frost kills them before they mature, by cutting them down when they first start to flower, or by tilling them into the soil.
Tilling cover crop into the soil is a common practice, but I don’t recommend it. Because tilling the soil even occasionally will result in a loss of soil life and potentially the creation of a hardpan layer just below the depth the tiller reaches.
In other words, you end up losing a lot of the nitrogen you were hoping to gain by growing the cover crop in the first place.
All these methods can be used to add nitrogen to your garden soil. But ultimately, promoting soil life is the best way to build rich soil and get abundant harvests.
Add Nitrogen to Your Garden Soil Indirectly
Garden soil is often treated as a static element that you amend and build by adding things to it. That the abundance in your garden is all through your own efforts.
But a better way to grow food is to work with nature by promoting soil life, and let that life do the work for you.
Garden soil isn’t static—it’s dynamic and alive. That life is ultimately the most important part of what makes rich soil abundant.
Here’s how it works:
As organic material breaks down, it feeds the life in the soil. This soil life then makes the nutrients that were in that organic material, including nitrogen, available to your vegetables.
But your plants also feed the soil life by releasing what is known as exudates. You can think of these as little packets of food for beneficial soil life.
So there’s this constant arrangement between plants and other types of soil life, where nutrients are being shared and recycled in the underground food web again and again.
Through this exchange, nutrients in the soil that your plants couldn’t access are made available to your plants. In addition, fungi can directly connect to the roots of your plants and essentially expand your plant’s root zone.
This partnership with fungi gives your vegetables access to nutrients that would normally be far out of reach.
Fungi, along with other soil life like bacteria, will greatly increase the amount of nutrients available to your plants, including nitrogen. You just have to support this soil life.
7. Stop tilling
Tilling can provide a quick boost. But it also degrades the soil structure, and depletes the soil of nitrogen and other nutrients the more you do it.
When you stop tilling, you give soil life an opportunity to grow and multiply.
The exception is one-time-tilling to get a new garden area preped the first time. This can actually speed up the process of soil building.
When you plant a diverse mix of plants, you ramp up the constant giving-and-taking pattern of nourishment that exists between plants and soil life, effectively extending the reach of their roots and allowing plants to get just what they need, right when they need it.
Having a diverse mix of plants results in a diverse mix of soil life which results in more nutrients including nitrogen being available to your plants.
All of this lets your plants access nitrogen and other nutrients that would normally be out of reach or just not available.
When you keep the soil covered by mulch, you’re supplying a constant supply of organic material to feed the soil life beneath the surface. (If you use a compost mix as your mulch, you can amplify this effect even more.)
As the soil life multiplies and consumes the mulch nutrients including nitrogen will be released for your plants. Over time this process results in nice deep rich soil.
Bonus: Another note on Compost
Adding compost will give your plants a solid dose of nitrogen, but it also offers a tremendous injection of soil life into your garden ecosystem.
In this way, compost is both a medium-term option as well as a long-term soil-building option for getting nitrogen and other nutrients to your plants.
You can make a rough compost with wood chips that can double as a mulch. This provides the benefits of mulch while also adding nitrogen and other nutrients to your garden.
Ultimately, garden soil with thriving soil life can eliminate the need for amending with nitrogen-rich material or anything else.
But it can take time to develop this soil life. The methods outlined earlier can help you transition to the point where soil life can take over the work of providing nutrients for your plants.
Building Garden Soil for Abundant Harvests
Dark, rich soil is the ultimate goal of any gardener. But sometimes you need to give your plants a nitrogen boost while you’re building this soil.
As important as nitrogen is, though, it isn’t the only nutrient your plants need. This is why the ultimate goal should be dark, rich soil that is filled with soil life.
Soil life will make all nutrients—regardless of your soil quality—more readily available to your plants. Amendments are often used to deal with deficiencies in nutrients. But this isn’t needed in the long run as long as soil life thrives.
You can read more about this principle in the 2nd part of a great 2-part series by Dr. Elaine Ingham:
But while you’re working to build your soil life, don’t forget that you can give your plants a boost of nitrogen if they’re showing signs of nitrogen deficiency. And you can add compost and grow nitrogen-fixers to add nitrogen to your soil each year.
And eventually, as long as you keep supporting soil life, you will be able to stop adding nitrogen directly and instead just rely on the soil life to do the work for you.
This is the ultimate goal. And the end result is more abundance with less work.
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