How To Add Nitrogen to Soil

Nitrogen is one of the essential elements for healthy plant growth and development. 

From being a constituting element of the chlorophyll molecule and amino acids to working as the primary building block for plant protoplasm (the translucent living matter in cells), nitrogen plays a critical role in several physiological and biochemical functions of plants. 


While nitrogen is naturally present in the soil, not every type of soil contains enough of it. 

Even when the nutrient is present in abundance, it often gets depleted with time because of its excessive usage by plants, environmental changes, soil erosion, crop removal, volatilization, and denitrification. 

Very high soil pH and some plant diseases, like fusarium piggyback, can lead to the development of nitrogen deficiency in plants. 

Soil also tends to lose nitrogen during hot and rainy weather.

The gradual loss of nitrogen makes plants prone to developing nitrogen deficiency.

What is Nitrogen Deficiency and What Damage Does It Cause to Plants?

When plants do not get an adequate amount of nitrogen, they develop nitrogen deficiency – a condition which affects their health in several ways and leads to poor or stunted growth. 

How to Identify Nitrogen Deficiency in Plants?

Here are some of the common symptoms of nitrogen deficiency:

  • Slow or stunted growth – less branching, thinner stems, reduced leaf size, lack of luster on leaves, and pale color of the plant, as a whole.
  • Increased growth of the plant roots, but poor or stunted shoot growth leading to poor shoot to root ratio.
  • Yellowing of leaves due to decreased production of chlorophyll. 
  • Wilting of older leaves.
  • Premature shedding of leaves
  • Some lower leaves, petioles, and stalks may turn purple.
  • Reduced flowering.

Since soil can lose nitrogen in many ways, it often needs to be supplemented with the nutrient from outside. 

However, you have to be very careful as too much nitrogen may be damaging to plants. 

Excessive supply of nitrogen can affect the root growth and fruit development. 

Fruits not only take longer to ripen but are also softer than usual. 

They also have a shorter storage life. 

Many times, the plants supplied with more than the needed amount of nitrogen do not bear any fruit or vegetable. 

Adding a large amount of nitrogen into the soil also poorly affects plants’ tolerance to cold weather and their water efficiency. 

Excessive nitrogen supply will increase leaf production and growth, but poorly affect plants’ health.

The best way to prevent excess nitrogen supply to your plants is soil testing. 

It will not only help confirm your diagnosis but will also help you determine the amount of nitrogen the plant(s) need. 

Either get the soil tested from your local extension office or do it on your own by using a soil testing kit.

Treating Nitrogen Deficiency – How to Add Nitrogen to Soil?

Here are some tried and tested ways to treat nitrogen deficiency in the soil:

Use a Chemical Fertilizer

One of the easiest and quickest ways to overcome nitrogen deficiency in plants is to feed it with nitrogen fertilizer, i.e., a fertilizer containing a high amount of nitrogen. 

For those who do not know, the first number in the NPK ratio mentioned on commercial fertilizers represents the amount of nitrogen in it. 

While it’s possible to use any all-purpose fertilizer, nitrate and ammonium-based fertilizers work the best. 

For better results, choose from ammonium nitrate, ammonium sulfate, calcium ammonium nitrate, or urea. 

Use urea for foliar feeding – another quick method to treat nitrogen deficiency in plants.

Organic Methods to Add Nitrogen to Soil

Whether you’re growing an organic garden or avoiding using chemicals on your plants for general health and environmental reasons, here are some organic ways to treat nitrogen deficiency in plants:


Animal waste is one of the best natural ways to add nitrogen to the soil. 

While it’s possible to use fresh animal manure, the waste of some animals, like chicken, is very high in nitrogen and, when used fresh or without composting, can burn the plants. 

Older and composted manure is not only well-tolerated but also more easily absorbed.

Adding rabbit, sheep, cow, horse, or duck manure is a great way to replenish soil nitrogen along with adding some other nutrients, like zinc and phosphorus.

Animal manure works like a slow-release fertilizer, offering support to plants not only during the growing seasons but throughout the year.

Coffee Grounds

Coffee grounds are also a good source of nitrogen for plants. 

In addition to nitrogen, it supplies the soil with copper, magnesium, phosphorous, and potassium. 

Coffee also helps to keep certain harmful pests away from your plants. 

To treat nitrogen deficiency in plants, either sprinkle the coffee grounds in the garden directly on the soil or add them to the compost pile. 

When used directly, water the plants immediately afterward, so the coffee grounds get dissolved into the soil.

Water the plants with a weak coffee infusion to add nitrogen to the soil.

Grass Clippings

Don’t throw away the grass after mowing your lawn. 

Use it to bring the soil’s nitrogen levels back to normal, along with improving the potassium levels as well.

Spread the grass clippings, in thin layers, around the base of the plants, or add them to the compost to replenish these essential nutrients naturally.

Leaf Mulch

Another way to improve the nitrogen level of the soil is to apply about a 3″ inch layer of leaf mulch on the garden bed followed by an adequate amount of water. 

This is also a great way to increase the concentration of organic matter in the soil, which then improves soil fertility.

Grow Legume Plants

The species of the legume family, like beans and peas, are known for their amazing nitrogen-fixation properties. 

They readily convert nitrogen present in the air into a form used by the plants. 

This is why they are considered great nitrogen sources. 

Adding a few legume plants to a garden is, therefore, considered a great way to treat nitrogen deficiency in the surrounding plants. 

Grow a Cover Crop

Cover crops, like clover and vetch, are not only nitrogen fixers, but also work as the source for green manure. 

Consider growing one if you have enough space.

While there are many organic fertilizer products available in the market, these are some of the best natural sources of nitrogen and work great for replenishing nitrogen – an essential element of healthy soil. 

Some other natural ways to increase the concentration of nitrogen in the soil include using crushed eggshells, wood ash, fish tank water, bone meal, blood meal, fish emulsion, and kelp.