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Grow cabbage like this if you learn how to add nitrogen to soil

How to Add Nitrogen to Soil

Plants need at least 17 essential nutrients to grow. Organic nutrients as a whole are great sources for your plants. Plants need nutrients just like you and I.

Plants with light green/yellowing leaves might be deficient in nitrogen. Nitrogen deficiency is common in plants.  Nitrogen is one of the essential macronutrients that plants need. Natural soil may have some of the necessary nutrients, but the majority of these nutrients need to be added to assist your plants in maximizing their potential. Which is far greater than you might think.

Figure 1: Nitrogen Deficiency 

Although we have an abundance of organic nitrogen in our atmosphere, it cannot be used by plants. Atmospheric nitrogen (N2) is a diatomic molecule held together by a triple bond. Triple bonds are difficult to break apart.

Instead, plants prefer nitrogen in the form of ammonia or nitrate. In forests, for example, nitrogen-fixing microbes such as fungi and bacteria work with plants by converting nitrogen into a usable form via the nitrogen cycle.

Plants can then absorb ammonia and nitrates through their roots through assimilation. These forms of nitrogen usually enter the roots during the absorption of water. 

In this article, we will explore different ways to add nitrogen to soil. 

Why Do Plants Need Nitrogen?

Plants need micro and macronutrients for healthy growth and development. These nutrients include nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, manganese, chlorine, molybdenum, nickel, and zinc. Plants get hydrogen, oxygen, and carbon from the air and water. 

Plants require a lot of nitrogen, hence why we call it a macronutrient. Most fertilizers contain and NPK mix. Nitrogen, phosphorus, and potassium are the three most important macronutrients needed for plant growth. These three nutrients help your crops grow, develop healthy roots, and produce a high crop yield. 

Typically nitrogen demand increases as the size of the plant increases. An abundance of nitrogen is also needed during the vegetative growth stage. It is not uncommon for plants to be deficient in nitrogen. 

We need to know why plants need nitrogen so we can understand how to provide it for them. Nitrogen is needed for plant growth; chlorophyll production; production of DNA and RNA; synthesis of ATP and coenzymes; for processes like photosynthesis; and reproduction. Similar to humans, plants need protein to grow and develop.

Nitrogen is a component of amino acids, which make up proteins. So, plants need nitrogen so they can synthesize proteins! Proteins are an important biomolecule responsible for plant structure, enzymes, ATP production, and biochemical reactions. 

Some plants can also take in amino acids. Enzymes called proteases help break down the amino acids within the plant.

Legumes are nitrogen-fixing plants and can make their own nitrogen because of their symbiotic relationship with rhizobia bacteria. The plants allow bacteria to invade and grow on their roots. In return, the bacteria form nodules and transform atmospheric nitrogen into ammonia. 

Rhizobia bacteria form nodules on the roots of legumes. These nodules are important little bumps because they are nitrogen-fixing specialists. Different legumes have different amounts of nodules and hence different nitrogen-fixing capabilities.  Soybeans can have hundreds of nodules per plant, while peanut plants have thousands of nodules per plant. 

Figure 2: Rhizobia Bacteria on Soybean Roots

Soil contains some amount of nitrogen because of microbes that are already present. These nitrogen-fixing microbes will slowly break down organic matter and transform nitrogen into a usable form for plants (ammonia and nitrate).

If you have high crop turnover on your land there will be more nitrogen available. It is possible that this will not be an adequate amount of nitrogen for the plants. The nitrogen released during decomposition is in low amounts and generally happens very slowly. 

Since nitrogen is one of the essential nutrients that crops need, we need to figure out ways to add nitrogen to soil. The levels of nitrogen that plants need vary based on their stages of development.

Crops in early vegetative stages need a lot of nitrogen since the cells are reproducing and multiplying. You want to maximize growth during this stage so you harvest a higher crop yield. 

Plants can readily take in nitrogen in the form of ammonia. The roots of the plant absorb ammonia either for the plant to use or it is released back into the atmosphere. 

Nitrogen might be present in the soil from organic matter (ie: from crop rotation & tilling), but this is not a form of nitrogen that plants can use. Nitrogen often has to be converted into usable forms for plants by nitrogen-fixing microbes in the soil. 

But what about the nitrogen in the atmosphere? Although 78% of our atmosphere is composed of nitrogen, it is also not usable by plants. Through the nitrogen cycle, some nitrogen-fixing microbes transform nitrogen into ammonia or nitrates. Microbes obtain this nitrogen from decaying organic material and atmospheric nitrogen. Microbes add nitrogen to soil.  Plants can then assimilate this nitrogen via their roots. 

Figure 3: Nitrogen Cycle 

Plants need a lot of nitrogen, but what are some ways you can add nitrogen to the soil?

Sources of Nitrogen

If your plants need some nitrogen, Table 1 below gives a list of some of the ways to increase nitrogen in soil. If chemical fertilizer isn’t your cup of tea, many other organic options can also help boost nitrogen levels. 

The majority of these nitrogen sources are in powder form and can be directly added to the soil.  Organic fertilizers (N-P-K mixes) contain nitrogen in the form that plants can use.

It is helpful to water the soil after you put these sources on so that the nutrients sink into the soil. Crops will take in the nutrients through their roots.  It is also helpful to add the nutrients to the soil before planting or a few months before planting so that the soil is fertile when it is time to plant. 

Decomposition in compost piles is a slow process done by nitrogen-fixing microbes as they break down organic matter.  Also, many of the sources listed below can be added to your compost pile. You can then use your compost pile as a nitrogen source for your crops. 

Table 1: Sources of Nitrogen for Plants 

Source of NitrogenApplicationBenefits 
Organic Fertilizers Mix into the soil before planting.Organic nitrogen, phosphorus, and potassium fertilizers are a great addition to help provide your plants with nutrients. Organic nitrogen fertilizers help to boost nitrogen levels in the soil.
Fish EmulsionFish emulsion can be added to soil or sprayed on plants. You can also add it to your compost pile.Fish emulsion is an organic fertilizer that is full of many nutrients, especially nitrogen. It is easy to use.
Alfalfa Meal Sprinkle powder onto the soil around plants.Alfalfa meal is made from dried-up alfalfa plants. It is a great source of nitrogen. Another benefit is that, unlike blood meal, it does not attract animals. 
Blood MealBlood meal comes in powdered form and can be added directly to the soil surrounding plants.Blood meal is made from dried animal blood. It is a great source of nitrogen for your plants. Blood meal contains high amounts of nitrogen so be sure to add the correct amount.
CompostCompost can be added directly to the soil. Be careful not to add too much so that there is not an overabundance of nutrients. Compost is beneficial because it is decomposed organic matter. Some items you may have added to your compost are leaves, food waste, branches, and twigs. Animal manure can also be added to your compost. Animal manure (from chickens, cows, horses, and rabbits) is very high in nitrogen. Microbes break down the organic matter and form compost rich in nutrients. 
Legumes Plant legumes between your crops. Technically legumes are considered nitrogen-fixing plants because of their symbiotic relationship with bacteria. This aids in adding a great amount of nitrogen to your soil.

How to Add Nitrogen to Your Soil

Since we know plants need nitrogen and we have to add it to the soil, how do we do it? Managing the levels of nitrogen in soil can be tricky because nitrogen levels are always in flux due to the nitrogen cycle. We want the amount of nitrogen to be just right. It is common for plants to be deficient in nitrogen. 

If nitrogen levels are too low it can lead to slow crop growth, low yield, or plant death. Low nitrogen is often the result of heavy rains, leaching, or sandy soils. Add nitrogen and nutrients to your land early so that there is no delay in the plant’s fruit production. 

High levels of nitrogen are not beneficial for crops or the environment. Too much nitrogen in the soil can also lead to plant death. Nitrogen in excess can leach down into the water supply and contaminate it.

There are soil test kits you can use to get a rough idea of what you’re working with, but the best is if you can get professional tests of different areas of that you’re growing in. Another option is sending your soil samples out to a lab.

Plants in a vegetative growth stage need high amounts of nitrogen. During this stage, there is rapid cell division and replication. Leaves and roots grow quickly and they need nitrogen to do this properly. The need for nitrogen is also directly proportional to the size of the plant. Larger plants will need more nitrogen to support their development and biochemical processes. 

Most nitrogen sources are added directly to the soil. It is important to place nitrogen throughout your field so that it can be accessed by all plants. Even distribution is best. After adding the nitrogen nutrients (in whatever form you choose), be sure that the soil is moist. Nitrogen will be absorbed by the roots when they are taking in water. If the soil is dry, the nitrogen can be released back into the atmosphere before it reaches the roots of the plant.

Timing is everything when making sure you have nitrogen-rich soil. Crops like wheat and corn need more nitrogen in the spring and summer. If rainfall is suspected to be heavy during those seasons, nitrogen needs to be added before and after plants begin to grow. 

The absolute easiest way to add nitrogen to the soil is using a product like Bio Grow from Green House Feeding. Yes, it is a time release product that delivers nutrients over the course of 8 week as it is broken down in the soil. But more importantly it is a carefully crafted blend of organic ingredients that work synergistically to boost your crops growth maximally.

Nitrogen is much more effective when balanced with the other nutrients a plant needs to grow, after all a plant needs around a minimum of 17 essential minerals to grow. 

This nutrient is in powder form so it is easy for you to apply and easy for your plants to absorb through their roots. It is a win-win! 

The BioGrow line promotes microbial growth in the soil. More microbial growth = more nitrogen for your crops! Get your BioGrow just in time for the growing season! 

Summary

Nitrogen is a macronutrient that plants need for healthy growth and development. It is not uncommon for plants to be deficient in nitrogen, but not to worry because many organic sources can be added to your soil to boost nitrogen availability for your plants.

Although there is nitrogen all around us in our atmosphere, plants cannot use atmospheric nitrogen or organic nitrogen. Plants can only assimilate nitrogen in the form of ammonia or nitrate.  Nitrogen-fixing microbes, like bacteria and fungi, play an important role in providing plants with the nitrogen they need.

Some ways to boost nitrogen in the soil are by adding blood meal, alfalfa meal, compost, urea, fish emulsion, legumes, and organic fertilizers/nutrients.  BioGrow plant nutrients are a great source of nitrogen for your soil. 

References:

Crop Nutrition

Nitrogen in the Plant 

Nitrogen Sources for Organic Crop Production

Nitrogen Fixation by Legumes 

Figure 1: Nitrogen Deficiency

Figure 2: Rhizobia Bacteria on Soybean Roots

Figure 3: Nitrogen Cycle 

Published
Categorized as Nutrients

By Talissa Nahass

Talissa is a secondary science educator who loves teaching biology and environmental science. She has her B.S. in Biology/ Secondary Education and her M.A. in Educational Leadership. In her spare time, she enjoys doing science research and writing. She has a passion for hiking, running, and being outdoors. Every spring she grows various fruits and vegetables in her garden.

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