By Bethany Cihon
Garden soil is an intricate web of nutrients and vitamins, working together to grow and nourish your plants. One of the essential nutrients is nitrogen, and a deficiency will quickly show both in the appearance and growth pattern of your plants. If you suspect a nitrogen deficiency in your soil, you need to know how to add nitrogen to the soil and proper correction methods.
Nitrogen is one of the three most essential nutrients. You might have heard of NPK – nitrogen, phosphorus, and potassium. These are the three big wigs when it comes to what your plant needs for growth.
So, when your garden lacks nitrogen, it will let you know so in big ways. From stunted growth to death of your plant, they can’t grow or survive without nitrogen. So, let’s look at how to add nitrogen to the soil and why it’s such a vital piece of your gardening puzzle.
Why Is Nitrogen Necessary for Plants?
Plants rely on many nutrients and vitamins, and one of the critical elements needed by plants is nitrogen. It’s part of the big three – NPK, which stands for nitrogen, phosphorus, and potassium. Plants need these three key vitamins without growth, and deficiencies can lead to significant problems.
Plants use nitrogen to make themselves, essentially. When plants lack nitrogen, they cannot make proteins, amino acids, and even their DNA. A nitrogen deficiency leads to stunted growth and death; plants are unable to make their cells.
Nitrogen exists all around us; it makes about 78% of the air we breathe each day. However, that’s not a usable form for plants. Instead, they need nitrogen in the soil because the plants in your garden easily convert it.
Soil Testing for Nitrogen Deficiencies
The best way to determine if you have a nitrogen deficiency is by testing your soil, but no homemade test can accurately test. You need to either purchase a soil testing kit or send your soil to be tested by a professional. Another option is to ask if your local extension office offers soil testing services; typically, it’s just a small fee or free.
If you prefer to test your soil at home, you can use a kit found at most garden centers or hardware stores. While the home tests aren’t professionally accurate, they can still give you a close-to-accurate result that you can use to determine if you have nitrogen deficiency present.
Testing your soil is the first thing you should do if you suspect a nitrogen deficiency. Adding more nitrogen to the soil that already has sufficient amounts will do more harm than good to your garden. It can burn or kill your garden plants!
Signs of a Nitrogen Deficiency
Since nitrogen is a necessary nutrient, your plant will display visible signs that there is a problem. It’s needed for your plant’s growth and development, so most gardeners will notice signs of a nitrogen deficiency when the plants are young. If you catch the problem early, you can fix it, and your plants will bounce back rapidly.
Here are some signs of nutrient deficiency.
- Slow and stunted growth
- Smaller than average leaves
- The lower leaves start to turn yellow first and might fall off from the stem.
- The upper leaves appear the usual green, but over time, the yellowing creeps up the plant.
- You’ll notice smaller than average flowers that die faster than average.
- If the plant lives to fruit, they’ll be smaller and lower quality.
How to Add Nitrogen to the Soil
Once you’re sure that you have a nitrogen deficiency, you have to fix your soil and add more nitrogen. Using organic methods takes time, but it will end up more evenly distributed over time. You can use non-organic methods, but you increase the risk of accidentally burning your crops if you add too much to your garden.
Here are some options to try if you need to add nitrogen to the soil in your garden beds.
Add Composted Manure
Animal waste is high in nitrogen; it’s so high that you typically cannot add animal waste directly to the soil, or it will burn your plants. The type of manure that you use varies in its “hotness,” so you need to compost it before adding it to your garden for at least six months. You can toss the manure right in with your food and garden waste in your compost.
Chicken manure is considered the hottest manure, so you definitely need to compost it first. Cow manure, along with goat and rabbit droppings, isn’t as hot, and you could add them to your soil with a reduced chance of burning. It’s typically safer to compost, especially rabbit droppings, before applying them to the soil.
It takes time for manure to decompose and work its way into the soil, so if you want the nutrients immediately, this isn’t your solution. However, it’s the best route because it’ll last the longest in the soil.
Use a Green Manure Crop
Have you heard of cover crops? Some crops can be planted in your garden beds that previously held nitrogen-hungry plants to fix the nitrogen deficiency.
The main difference between growing a green manure cover crop and planting beans or legumes to fix nitrogen is that a cover crop is not grown for harvest. You typically plant at the start of the season or in the off-season.
The downside to using green cover crops is that it takes a lot of time and effort for a home gardener to remove them from the garden.
Plant Nitrogen-Fixing Plants
Some plants are considered nitrogen-fixing plants, which means that they’ll add nitrogen to your soil as they grow. The two main ones to add to your beds are beans and legumes.
Instead of absorbing the nitrogen from the soil, they fix the nutrients. So, consider growing beans and legumes where you previously grew nitrogen-hungry plants in the previous year. This is one reason that crop rotation is so vital and should be planned out for several years.
It’s also important to note that you should cut back or avoid fertilizing the garden beds or areas where you grew bean crops in the previous year. You might end up with too much nitrogen in the soil.
Mix Coffee Grounds in the Soil
Are you a coffee lover? Perhaps you have a friend who works at a coffee shop, and they might save you used grounds for free.
Coffee grounds are an excellent source of nitrogen. You can either add them to your compost pile or mix the grounds directly into your soil. It takes time for them to break down and release into the soil, but a bonus is that coffee grounds help to aerate the ground and improve drainage.
Use Fish Emulsion
Another nitrogen-rich fertilizer is called fish emulsion; it has an NPK ratio of 5:1:1. That means, while it does provide nitrogen to your plants, the dose isn’t high enough to burn your plants.
One benefit to using fish emulsion is that it also contains various other micronutrients that benefit your plants, such as:
Most garden centers sell fish emulsion in a concentrated form that needs to be mixed with water. The average ratio is 2-3 tablespoons of fish emulsion for every one gallon of water. Then, you pour it on the soil or spray the leaves of your plants.
If you happen to have a fish tank, don’t dump out the water. It’s a free, lite version of fish emulsion. Fish poop in the water and fish droppings contain plenty of nitrogen. You can water your plants with the fish water, and it makes the nutrients available immediately for the plants to use.
Spread Grass Clippings As Mulch
In the summertime, you spend a lot of time cutting grass, so use those free clippings to your advantage (as long as you don’t use any pesticides or chemicals on your lawn). You can apply grass clippings in your garden bed as an organic mulch. As the grass clippings decompose, they leech nitrogen back into your soil.
Use an Actual Plant Fertilizer
Nitrogen is present in chemical fertilizers, as well as organic ones. When you select a plant fertilizer, look for one with a high first number in the NPK ratio. The ratio is displayed on the package of the fertilizer, looking something like 10-10-10 or 20-20-20.
The first number indicates the amount of nitrogen, so using one with a larger first number gives a significant boost to your soil. However, a negative is that chemical fertilizers do tend to fade away faster and can also burn your plants by providing too much nitrogen at once. The organic ones usually have lower numbers, but take longer to be absorbed.
Unlike some other nutrients, adding too much nitrogen can be quite problematic, so it’s suggested that you DON’T do all of these things. Pick what will work best in your situation – whether you need a quick fix or amend your soil for the upcoming season – and use the method that will work the best. Always follow appropriate dosages that are recommended on any packaging.