Your garden isn’t flourishing as well as last season, and some of your favorite flowers aren’t as sizeable, or they are perishing faster than previously before. You may wonder if it’s due to nitrogen-deficient soil and, if so, how to add it to soil anyway?
Add nitrogen to soil with organic or non-organic fertilizers. Organic ways to increase nitrogen include compost manure, coffee grounds, fish emulsion, green crops, bone meal, alfalfa meal, and feather meal. At the same time, non-organic methods include urea, ammonium nitrate, or regular fertilizer.
Nitrogen in soil is one of three macro-nutrients vital to encourage proper plant growth. So, let’s look at why adequate nitrogen is essential for plants and how to add nitrogen to nitrogen-deficient soil.
How to Add Nitrogen to Soil
There are two alternative routes to fix the soil’s nitrogen deficiency, namely organic or non-organic. These two routes split into many effective ways to add nitrogen to your ground; however, the method you end up choosing is entirely up to you.
Your choice will depend on how often you would like to amend your soil, how speedily you need the added nitrogen to release into the soil, and lastly, what other nutrient deficiencies your soil has.
A few ways to add nitrogen to your soil include:
- Compost manure
- Coffee grounds
- Fish emulsion
- Nitrogen-fixing crops
- Blood meal
- Alfalfa meal
- Feather meal
- Ammonium nitrate
- Regular, broad-range, landscape fertilizer
Before digging into the exact “what to know” of each option, let’s start briefly discussing why nitrogen is essential in soil and how to identify if your plants and soil are nitrogen-deficient.
Is Nitrogen Essential for Plant Growth?
Nitrogen is an element that exists naturally in the earth’s atmosphere. It enables the earth’s living things to create protein and combines with other vital parts to complete activities essential to plants and life.
Of all the nutrients plants need, nitrogen is one of three primary macronutrients crucial to thriving.
Try to think of nitrogen as the primary fuel for plant growth. Its purpose is to help plants grow to sizeable plants with lush, green foliage and strong stems.
Nitrogen is involved in several plant processes, including photosynthesis, enzymes, cell and tissue growth, protein formation, and the formation of chlorophyll (allows plants to receive energy from light).
Without nitrogen, a plant can’t make proteins, amino acids, or DNA. A lack of nitrogen is why plants have stunted growth when there is a nitrogen deficiency in the soil.
So, as you can see, nitrogen is essential for plants to grow and survive; therefore, if you think your plants are nitrogen-deficient, it’s best to treat the soil as soon as possible.
How to Identify a Nitrogen Shortage
Even though nitrogen makes up 78% of the air we breathe, you may be wondering why you need to test the soil if nitrogen is accessible everywhere?
For plants to have access to nitrogen, it needs to be converted into nitrates in the soil through nitrogen fixation. So, can you be sure if your plants have a nitrogen deficiency?
You can identify nitrogen deficiency in two ways:
- Observe the overall health of your plants
- Conduct a DIY soil test
Let’s briefly look at both methods.
Signs of Nitrogen Deficiency in Plants
Plants will visibly display several signs if there is a lack of nitrogen in the soil.
The most common signs of nitrogen-deficient soil include slow and stunted growth, smaller leaves and flowers than usual, and yellowing or lightening of the plant’s lower leaves (they may even fall off the stem).
The yellowing of the plant’s leaves can signify chlorosis, indicating low nitrogen levels in the soil. However, keep in mind that yellow leaves can also occur from seasons changing or overwatering.
Conduct a Soil Test to Test Nitrogen Levels in Soil
The second method entails performing a soil test. However, soil tests can be pretty tricky, and they aren’t always accurate either.
Soil tests are challenging due to the nitrogen availability constantly changing from the type of plants, moisture levels, and weather changes.
It’s advisable to use a DIY home soil testing kit for immediate results due to lab testing taking long enough to have inaccurate nitrogen results by the time they finish.
Note that even the DIY soil kits aren’t very accurate, but they provide a general idea of what’s going on in the soil. Inaccuracy occurs because soil tests indicate what nutrients are present in the ground but not how much of these nutrients are available to the plants to use.
However, testing your soil remains the first thing you need to do when suspecting a nitrogen deficiency. If your assumption is wrong, adding extra nitrogen to the ground with sufficient amounts will, unfortunately, do more harm than good to the soil and plants.
Excess nitrogen levels can burn and even kill your plants.
How to Add Nitrogen to Soil Organically
Increasing nitrogen organically takes time, but the reward is more significant as you will end up with evenly distributed nitrogen levels in your soil over time.
1 – Increase Nitrogen in Soil with Composted Manure
Animal waste is extremely rich in nitrogen; the nitrogen levels are high, so adding fresh droppings to the soil can burn the plants.
The most common animal manure fertilizer is a cow or poultry manure, but sheep, goat, horse, and rabbit manure work just as well.
The type of manure you use generally varies in “hotness,” so be sure to compost the waste before adding it to your soil to prevent it from burning your plants.
Chicken manure is the “hottest” and needs to be composted with food and garden waste in your compost for at least six months before adding it to your soil.
In addition, cow manure, goat droppings, and rabbit droppings tend not to be as hot. So, you can spread them directly onto the soil with little danger of burning the plants. However, it’s generally safer to compost all manure before applying them to the ground.
It takes quite a while for manure to decompose and work its way into the soil, so if you require nitrogen in your soil immediately, consider making a compost manure tea by soaking dry, well-aged manure in water for several days.
Discard the manure or droppings and pour the compost tea directly onto the plants that need it most. This method is especially beneficial for green, leafy plants.
2 – Use Coffee Grounds
This second organic method is perfect for coffee lovers! Coffee grounds are a brilliant source of nitrogen.
You can add the coffee grounds to your compost pile or turn the coffee grounds directly into the soil. Coffee grounds take time to break down, but they help aerate and improve soil drainage, making them worth the wait!
3 – Use Fish Emulsion
Another natural soil amendment for nitrogen-deficient plants is fish emulsion.
Fish emulsion has an NPK fertilizing ratio of 5:1:1 or 5:2:2, making it a mild fertilizer that provides nitrogen without burning your plants.
In addition, fish emulsion also contains numerous micronutrients beneficial to plants, including calcium, magnesium, sodium, chlorine, and sulfur.
If you happen to own fish, use the water from the fish tank to add nitrogen and other nutrients to your plants. In addition, fish emulsion makes the nitrogen and nutrients available immediately for the plants to absorb.
If you do not have a fish tank, you can purchase fish emulsion from most garden centers. Be sure to dilute the fish emulsion with water (2 to 3 tablespoons of fish emulsion for every gallon of water).
Once diluted, spray the mixture onto the leaves or pour it into the soil.
4 – Plant Nitrogen-Fixing Plants
Green cover crops, also known as green manures or nitrogen-fixing plants, are a great way to soil and water quality, and most importantly, recycle or add nitrogen to the ground.
Legumes are primarily associated with adding nitrogen to the soil due to their well-developed, mutually beneficial relationship with soil bacteria which convert nitrogen to ammonia nitrates for plants to use.
Once the cover crops decompose, nitrogen or ammonia nitrates are released from the plant residues back into the soil.
The main downside to using green cover crops like peas and beans is that it takes a lot of effort and time before the nitrogen is balances in the soil.
5 – Use Blood Meal
A blood meal is, as the name says, dried animal blood. This slaughterhouse by-product can contain up to 13% nitrogen, effectively adding nitrogen back into the soil.
A blood meal is water-soluble and can therefore be used as a liquid fertilizer to improve nitrogen levels in the soil.
In addition, blood meal is a fast-acting fertilizer that can effectively feed plants for 6 to 8 weeks with a single application. However, be careful to follow the instruction closely when applying bone meal to plants; the bone meal is highly concentrated, and too much can burn the plants.
For best results, dissolve the blood meal in water or mix it into the soil during planting.
6 – Alfalfa Meal
Alfalfa meal is a popular soil amendment that generally has an NPK ratio of 3:1:2.
You can find alfalfa as a meal or pellets; you can use both to fix nitrogen in your soil. However, pellets require a little more work as you first need to soak them to break them up into a powdered meal.
Alfalfa meal is a genuine powerhouse organic soil amendment; not only to replace lost nitrogen in your soil, but it also contains essential minerals like iron, calcium, magnesium, sulfur, manganese, copper, boron, and zinc.
In addition, alfalfa meal is fast-acting and breaks down quickly to provide your soil with the needed nitrogen.
The most common way to use alfalfa meal is to use it as a dry soil amendment that you broadcast over the soil.
7 – Feather Meal
Feather meal is the perfect solution if your soil is nitrogen deficient but has enough phosphorus and potassium as it contains no sources of phosphorus or potassium.
Feather meal generally contains 15% nitrogen by weight, but it tends to have a slow-release rate. Therefore, it is best first to add the feather meal to compost to aid in decomposition to speed up nitrogen-deficient plants’ breakdown and release process.
Tip: If you’re a homesteader with chickens, consider adding the chicken feathers to your compost pile.
Non-Organic Ways to Add Nitrogen to Soil
Although organic methods to add nitrogen to soil are the best options, they are generally slow releasing. Therefore, consider using these methods if you need to boost your soil’s nitrogen levels as soon as possible.
8 – Urea Increases Nitrogen in Soil
Urea is the most concentrated nitrogen fertilizer, containing 46% nitrogen of its weight. It is an inexpensive form of nitrogen fertilizer with an NPK ratio of 46:0:0.
Although urea is also naturally produced by humans and animals, synthetic urea is manufactured with anhydrous ammonia for nitrogen fertilizers.
Urea is most effective on moisture-retaining soil types; urea can be lost on light sandy soil when applied as top-dressing. However, when it is effectively washed or worked into the ground, urea works just as well as any other nitrogen fertilizer.
9 – Ammonium Nitrate
Ammonium nitrate is a widely used fertilizer for top dressing. It is a common source of nitrogen because it contains ammonium and nitrates.
Half of the ammonium nitrate’s content consists of nitrate, making it readily available to the soil.
However, ammonium nitrate is hygroscopic, meaning that it readily absorbs moisture from the air and forms clumps. So, it’s best to use ammonium nitrate fertilizer in dry conditions.
10 – Regular Landscape Fertilizer Increases Nitrogen in Soil
Regular, broad-range fertilizer typically contains a balance between the three major plant nutrients (nitrogen, phosphorus, and potassium).
Purchase a regular NPK fertilizer with a high nitrogen ratio; for example, 3:1:1 or 10:8:6. The best way to determine what proportion to use is to conduct a soil test before purchasing fertilizer.
Most artificial fertilizers generally release nitrogen and other nutrients relatively quickly into the soil; however, slow-release products are also available.
Nitrogen is one of 3 key building blocks essential for plants to thrive. If your soil has a nitrogen deficiency, you need to act fast to prevent stunted growth, yellowing leaves, fewer flowers, and less fruit.
Whether you add nitrogen to your soil organically or use non-organic fertilizer is entirely up to you.
However, note that organic methods require more patience as they are slow-releasing, resulting in an even distribution of nitrogen safe for the plants. In contrast, non-organic methods are fast-releasing and can quickly burn your crops if you use excessive amounts.
Ben has a bachelor’s degree in construction engineering. When not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies, you can find him at home with wife and two daughters. Outside of family, He loves grilling and barbequing on his Big Green Egg and Blackstone Griddle, as well as working on projects around the house.
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