Understanding the impact of fertilizers on the nitrogen cycle: What you need to know
Nitrogen is a crucial component of amino acids, proteins, nucleic acid, DNA, and RNA, so it is necessary for life on Earth. A fundamental biogeochemical reactions based cycle elaborates the nitrogen transformation into multiple nitrogen-containing compounds to sustain life, enhance soil fertility, balance ecosystems, and maintain environmental conditions.
Originally, nitrogen was produced in stars through nuclear fusion and released in the form of nitrogen containing gasses when these ancient stars exploded. Later, with the development of the earth, nitrogen became a significant component of the earth through this microbial derived nitrogen cycle.
The ancient growers were familiar with the importance of the nitrogen cycle. They were used to plant leguminous crops, boosting nitrogen-fixing bacteria and improving crop yields and soil fertility. But in the 19th century, scientists discovered the chemical nature of nitrogen, its role in plant nutrition, and the ways to boost its production in the soil. They also realized the role of nitrogen-fixing bacteria and processes to improve their production, understanding the process of nitrification and denitrification.
In the 20th century, the Haber Bosch process was the first industrial fixation of atmospheric nitrogen. Later, in the middle of the same century, it was identified that human activities play a key role in the nitrogen cycle. Similarly, it was also observed that the excessive use of synthetic fertilizers led to algal blooms and depleted oxygen in water bodies because of nutritional deficiencies or runoffs.
Today, extensive research is being done to adapt sustainable agricultural practices, including crop rotation and organic farming, to keep the nitrogen input and output balanced in the environment and soil.
Growcycle has been significantly helping growers effectively manage the nitrogen cycle, providing them with advanced tools and nitrogen based fertilizers.
They brought nitrogen stabilizers to slow down the nitrogen conversion and controlled release fertilizers in the market to fulfill the plant's need to maintain adequate nitrogen in the soil. They offer organic and eco-friendly nitrogen products and encourage growers to follow the 4R formula, which states that the right source, time, rate, and place are the right steps to get better results.
Importance of Nitrogen For Plant Growth
Nitrogen is essential in maintaining plant physiology and development because it is a critical nutrient that boosts plant growth. It is a key element in protein building blocks. As an enzyme, it plays a key role in catalyzing different biochemical reactions in the plant body. It also helps in chlorophyll production, which is essential for photosynthesis. It uses sunlight to produce energy to sustain various routine reactions necessary for plant growth.
Similarly, nitrogen is a DNA and RNA building block and is vital to transferring genetic information from one generation to the next. It helps plant leaf and stem growth, and an adequate nitrogen supply maintains and multiplies growth. Additionally, flower formation, fruits, and seeds all need a proper nitrogen supply to bring high-yield production and good-quality plant growth.
Besides these, nitrogen helps maintain abiotic stress in extreme weather conditions like floods, droughts, and extreme temperatures. It also plays a key role in disease resistance and plant immunity. However, if a plant suffers from nitrogen deficiency, it will cause chlorosis, which means the yellowing of leaves. Similarly, it will stunt the plant's growth and reduce crop output.
Key Stages of the Nitrogen Cycle
The nitrogen cycle consists of the following stages, which play a crucial role in nitrogen conversion, making it accessible and useful for plants.
Nitrogen Fixation
This is the first step of the nitrogen cycle, which includes converting the nitrogen into ammonia using certain types of bacteria and an enzyme named nitrogenase. The most commonly used bacteria are Rhizobium in legume root nodules and Azotobacter in soil.
However, in industrial nitrogen fixation, ammonia is produced using an iron catalyst by combining and compressing atmospheric nitrogen and oxygen. Nitrogen fixation can also occur through lightning and photochemical reactions, which break the nitrogen bonds and allow it to combine with oxygen, which enters the soil after dissolving it with rainwater.
Nitrification
In this stage, the ammonia is oxidized to nitrite, which is further oxidized to nitrate with the help of certain types of bacteria. The top bacteria are archaea, which significantly contribute to nitrification in fresh and marine water.
Assimilation
In this stage, the plant absorbs the nitrogen from the soil in the form of nitrates and ammonia and uses it to build protein, amino acids, and nucleic acids. In this stage, mycorrhizal fungi play a key role because they create a symbiotic relationship with the plant, improving the surface area of the plant root system and boosting the nitrogen absorption from the soil, leading to a healthier plant and getting desired nutrients for itself.
Ammonification
In this stage, bacteria and fungi, like all decomposers, break down the plants and animals' dead parts, including dead leaves and dead cells, and then convert this organic nitrogen produced from organic matter back to ammonia or, in some cases, ammonium. But that’s not all; the urease-producing bacteria use organic waste from plants and animals and convert it into ammonia and carbon dioxide. This process of converting urea into ammonia is called ureolysis.
Denitrification
If the soil lacks oxygen or the environment has a poor oxygen supply, the denitrifying bacteria convert the nitrates again into nitrogen gas and release it back into the atmosphere. This process prevents water pollution and eutrophication, avoiding the accumulation of nitrates in the soil.
Natural Sources of Nitrogen in Soil
Nitrogen in the soil comes from multiple sources, each having a significant role in the Nitrogen cycle. Atmospheric Nitrogen becomes part of soil when plants or bacteria absorb it from the air in gas form and convert it into useful ammonia and related compounds to absorb for energy. During rainfall, atmospheric Nitrogen is absorbed in the soil and produced by a lightning process that converts it into ammonia and nitrate.
The decomposition process in decomposers also helps to convert the nitrogen gas into ammonia, which is absorbed into the soil and used by living organisms. Animal waste produces Nitrogen when decomposition from urine and excrement occurs, which is then absorbed into the soil through soil microorganisms.
Dust and ash, which come as wind particles and settle on the ground, have Nitrogen, which contributes to soil nitrogen. Further, volcanic eruptions and the relationship of plants with nitrogen-fixing bacteria, biomass, and roots of alfalfa or clover have Nitrogen, which they release into the soil.
Role of Microorganisms in the Nitrogen Cycle
Microorganisms are like nature’s tiny creatures, moving nitrogen from one medium to another in an ecosystem. Their role in the nitrogen cycle starts at the first step when Rhizobium and other cyanobacteria convert atmospheric nitrogen into ammonia.
After transferring atmospheric nitrogen into the soil, the nitrification process is again completed with the help of Nitrosomonas and Nitrobacter, who transform ammonia into absorbable nitrogen for plants. Microorganisms maintain the nitrogen balance in the environment, make it available for living organisms, and stabilize the ecosystem functions.
Types of Fertilizers with Nitrogen Content
Different types of fertilizers have nitrogen, each useful for different plants and soil types. Here are some common nitrogen fertilizers:
Ammonium Nitrate (NH4NO3)
Nitrogen Content: 34-35%
This fertilizer is very strong and easy for plants to absorb. It works quickly and lasts a long time.
Urea (CO(NH2)2)
Nitrogen Content: 46%
Urea is one of the most popular nitrogen fertilizers because it has a high nitrogen content. It dissolves well in water and can be applied directly to the soil.
Ammonium Sulfate ((NH4)2SO4)
Nitrogen Content: 21%
This fertilizer provides both nitrogen and sulfur, which are important for plant growth. It has less nitrogen than urea and ammonium nitrate but adds sulfur to the soil.
Calcium Nitrate (Ca(NO3)2)
Nitrogen Content: 15-17%
This fertilizer provides plants with both calcium and nitrogen. It dissolves easily in water and is quickly absorbed by plants, making it suitable for crops that need a lot of calcium.
Anhydrous Ammonia (NH3)
Nitrogen Content: 82%
Anhydrous ammonia is a gas that is injected into the soil. It has the highest nitrogen content of all fertilizers and is often used in large farms.
Sodium Nitrate (NaNO3)
Nitrogen Content: 16%
Also called Chilean nitrate, this natural fertilizer is good for dry areas. It provides nitrate nitrogen that plants can use quickly.
Ammonium Phosphate ((NH4)3PO4)
Nitrogen Content: Around 11-13%
This fertilizer gives plants both nitrogen and phosphorus, which are important during early growth stages. It is commonly used for crops that need both nutrients.
How Fertilizers Affect The Nitrogen Cycle?
Fertilizers leave a significant impact on the nitrogen cycle by dissolving rich nitrogen in the soil, and their use introduces changes in environmental outcomes:
1. Nitrogen Addition to Soil
Fertilizers, especially those with rich nitrogen content, such as urea and ammonium nitrate, release nitrogen in the soil and make it accessible for plants, which use it to grow fast and vigorously. Moreover, the enhanced nitrogen in soil helps the plants in protein synthesis. In contrast, the eutrophication process also occurs due to the release of fertilizers into waterways, which causes algae and weeds to grow and disturbs environmental oxygen.
2. Changes in Soil Microbial Activity
The application of fertilizers disrupts the natural balance of soil microorganisms. If synthetic fertilizers favor nitrifying bacteria for nitrification, organic material will help grow decomposers to boost the nutrient cycle.
Imbalance and excessive use of one type will affect the growth of second microorganisms and balance the microbial activity, affecting the nutrient cycle and soil health.
3. Environmental Impact
Excess nitrogen from fertilizers can leach into groundwater or run off into nearby water bodies. This can lead to water pollution, causing problems like algal blooms, which deplete oxygen in water and harm aquatic life.
Nitrogen fertilizers can contribute to releasing nitrous oxide, a potent greenhouse gas, into the atmosphere. This occurs during both nitrification and denitrification processes.
4. Impact on Natural Nitrogen Fixation Process
The additional use of synthetic fertilizers can disturb natural nitrogen fixation. Excessive nitrogen from fertilizers slows down the plants’ reliance on natural resources by fulfilling their needs from artificial supply. This suppresses the bacterial activity of nitrogen fixation. As a result, the crop rotational phenomenon and other natural processes that rely on natural fixation will receive slow performance.
5. Plant and Crop Impact
In the short term, nitrogen fertilizers promote vigorous plant growth and increased crop yields due to nitrogen supply. Excess nitrogen can lead to an imbalance of other essential nutrients in the soil, affecting overall plant health and potentially leading to nutrient deficiencies.
Positive Effects of Fertilizer Use
Fertilizers boost soil microbial activities, which help break down organic matter and recycle nutrients, improving soil structure and healthier soil ecosystems with more resilient crops. Compost and manure, like organic fertilizers, boost soil aeration, improve water retention capacity and root penetration, and reduce soil erosion while supporting plant health.
They make the roots bind with soil more effectively, leading to a more consistent and effective nutrient supply to the plant. This results in fast and steady growth and improves vegetable and fruit mineral and vitamin levels. Fertilizers enhance crop yields on existing farmlands without disturbing biodiversity and natural ecosystems. They also improve carbon sequestration, which helps the soil extensively store carbon dioxide and use it in plant growth, reducing climate change risk.
Fertilizers improve the water use efficiency of crops and plants, reducing the need for continuous irrigation, which results in budget and time savings. They also promote the growth of beneficial insects, like earthworms and beetles, which results in pest control and adequate plant pollination.
Negative Effects of Fertilizer Use
Excessive use of fertilizer causes soil acidification, resulting in reduced pH and metal leaching, the latter of which can be harmful for plant roots. Overapplication of nitrogen-rich fertilizers releases potential greenhouse gases, such as nitrous oxide, which has a 300-times greater global warming potential than carbon dioxide.
Excessive algae growth also leads to eutrophication and water pollution, resulting in algal blooms. These blooms create dead zones for aquatic life, where aquatic life becomes dead, which means it can’t survive.
Overusing fertilizers harms human health and disrupts the balance of microbes in the soil, making the soil less fertile over time. It can cause more diseases and pests, stress plant growth, and reduce organic matter in the soil.
Additionally, soil compaction from too much fertilizer decreases soil porosity, making it harder for roots to grow and reducing air in the soil. This overuse also raises farming costs for farmers, leading to lower yields despite higher expenses.
Best Practices For Sustainable Fertilizer Use
It is important to maintain an average and proper use of fertilizers to maintain the soil’s natural formation and ensure the healthy growth of plants. Here are some key practices for it:
- Checking the soil’s natural nutrient level, pH, organic matter, and other contaminators guides the farmers in selecting accurate fertilizers according to composition. Soil should be taken from different depths and locations for accurate results, which helps to make informed decisions about rotational crops and fertilizer application according to soil requirements.
- Application of fertilizers before planting is recommended to guarantee a robust beginning. Split methods can be considered to sustain a well-balanced nutrient distribution, and their usage during the wet season should reduce the likelihood of leaching and runoff.
- Coated and naturally slow-releasing fertilizers are most useful for preventing leaching and runoff as they ensure a steady nutrient supply to maintain plant continuous growth. Similarly, organic fertilizers are more favorable for soil structure and microbial activities.
- Implementing crop rotation can reduce pests and disease attacks on plants and help balance the soil structure; therefore, farmers should consider different crop families to improve soil health safely. Cover crops such as legumes and grasses can reduce soil erosion and improve the nitrogen cycle.
- Real-time monitoring of soil moisture, temperature, and nutrient level can guide accurate fertilizer application, and GPS-guided equipment can be used to map the exact location of nutrient deficiency.
Alternatives To Traditional Fertilizers
Alternatives to traditional fertilizers can naturally improve soil health, and their environmental impacts are not as harsh as chemical fertilizers, support sustainability in farming practices, and prove cost-effective; some of the important alternatives are:
Biological Nitrogen Fixation
Leguminous plants, such as peas, beans, and clover, improve soil structure and fertility best because they make symbiotic relations with nitrogen-fixing bacteria and use atmospheric nitrogen for their energy, which reduces the reliance on synthetic fertilizers. Cover crops are also used to prevent soil erosion and store nutrients in soil structure for other plants.
Compost and Vermicompost
Compost is made from decomposed materials, which boosts water retention and improves microbial activity for better nitrogen recycling. Incorporating vermicompost also breaks down the organic material to improve soil structure, micronutrient availability, and soil aeration. It also helps the growth of beneficial microorganisms.
Biochar and Other Soil Amendments
Crop residues and wood produce biochar. Its application in soil amendments helps reduce soil acidity, promote fertility, and improve water retention properties. Lime, rock phosphate, and gypsum also improve soil pH and drainage properties.
Integrated Nutrient Management Approaches
The use of organic and inorganic combinations, improvement in nitrogen cycling by crop rotation and cover crops, efficient monitoring of soil structure, and strategic application of required fertilizers can improve the management approaches and leave less impact on the environmental structure.
FAQS
Are there any household items I can use as natural nitrogen fertilizers?
Several items from the house kitchen can be used, such as coffee powder, leftover vegetable water from cooking, banana peels, grass clippings, and egg shells. These are some popular examples of items that have rich nitrogen and safely foster plant growth.
How can I calculate the right amount of fertilizer for my garden size?
Measuring all garden areas in square feet is necessary to calculate the amount of fertilizer needed. After measurement, the soil test result is checked to finalize the fertilizer amount for 1000 square feet. For those who have not reported soil tests, measuring 2-4 pounds of nitrogen for a 1000 square feet area is recommended.
Are there any risks to pets or children from commonly used nitrogen fertilizers?
Commonly used nitrogen fertilizers contain chemicals named nitrogen, phosphorus, and potassium, which can harm pets and children. Ingestion of such chemicals can cause diarrhea, vomiting, and skin irritation in pets. The same symptoms can be seen in children due to the potential poison in fertilizers.
The Bottom Line
The nitrogen cycle is highly crucial to sustaining life on Earth, but excessive nitrogen leads to significant plant health issues along with soil and environmental destruction. To avoid these issues, it is recommended that biochar be integrated, which reduces nitrogen leaching while boosting the soil's nutrient retention capacity.
Similarly, microbial inoculants boost nutrient uptake to avoid mishaps while reducing the need for synthetic fertilizers. Additionally, the fertilizer micro dosing helps improve nutrient use efficiency on a limited budget and mitigate environmental impacts.
Growcycle provides affordable and essential tools, products, and services that every gardener needs for soil preparation, management, plant growing, harvesting, and storage. They offer different customized fertilizers for healthy plant growth, including fish emulsions, organic compost, vermicompost, and bone meal. From soil testing to gardening tips and harvesting, they guide the user at every step.
Disclaimer: This material is for informational purposes only and should not be relied on for legal, medical, financial, or other professional advice.
About the Author
Victor Miller 
Environmental Journalist Focused on Sustainable Agriculture
Victor Miller is an environmental journalist at Growcycle, where he covers the latest news, trends, and innovations in sustainable agriculture. He has a deep passion for storytelling that emphasizes ecological balance and responsible farming practices.
Before joining Growcycle, Victor worked for several agricultural and environmental publications, reporting on significant environmental issues and interviewing key figures in the sustainability sector. His work has been featured in various industry journals and online platforms.
