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  • Writer's pictureJere Folgert

What is Nitrogen and Why do Plants Need it?

Updated: 1 day ago

Nitrogen: The Unsung Hero of Bumper Crops

Ever wondered why some farms consistently bring in massive harvests? It's not just magic (although sometimes it feels that way). A significant player in this agricultural alchemy is nitrogen – the unsung hero of crop yields.

Nitrogen isn't just good for plants in a vague, "healthy" kind of way. It's like steroids for protein production. Here's the science behind the magic:

  • The Protein Powerhouse: Nitrogen is a fundamental building block of amino acids, the tiny molecules that link up to create proteins. Think of proteins as the workhorses of the plant world – they're responsible for everything from building strong structures to speeding up vital processes. With ample nitrogen, plants can crank out more protein, leading to sturdier stalks, lusher leaves, and ultimately, a higher crop yield.

  • Direct Protein Boost:  Nitrogen isn't just an indirect contributor to protein content. It's actually incorporated directly into some plant proteins themselves. This means that with sufficient nitrogen, crops not only grow bigger, but their nutritional value also gets a significant boost. Think of it as nitrogen fortifying your food source – a win-win for farmers and consumers alike!

The Nitrogen Fix: How Plants Get the Green Light to Grow

Imagine a world overflowing with air, but plants are gasping for breath! That's because even though most of the air is nitrogen, plants can't use it directly. It's like having a locked treasure chest of fertilizer right above their heads!

Here's the twist: nitrogen needs a makeover to become plant food. Luckily, there are tiny heroes in the soil called nitrogen-fixing bacteria. These bacteria act like microscopic factories, breaking the strong bond between nitrogen atoms (N₂) and turning them into usable forms like nitrate (NO₃⁻) and ammonium (NH₄⁺).

What is interesting is that plants are picky eaters. They mainly want nitrate, while some settle for ammonium. The handy dandy table shows the nitrogen A-listers (nitrate and ammonium) and the locked-away dinitrogen (N₂).

Now, let's talk about chlorophyll, the green superhero in leaves. Chlorophyll needs nitrogen to capture sunlight and turn it into sugary goodness for the plant to grow. No nitrogen, no chlorophyll, and plants become pale and weak.

Nitrogen is like a celebrity in the plant world. It's everywhere – in leaves, stems, roots, and even those yummy fruits and seeds we love. It helps build strong plant bodies, fuels growth, and makes yummy proteins. But nitrogen isn't the only star. Plants need a whole squad of essential elements, like phosphorus and potassium, to truly thrive. These elements are like vitamins for plants, helping them with everything from healthy roots to fighting off disease.

What Form of Nitrogen do Plants Like Best?

In a perfect world, plants would love to chow down on ammonium (NH4+). It's like pre-digested nitrogen, ready for them to absorb easily. But there's a catch:  ammonium is a bit of a shy guy.  It sticks around in the soil, afraid to move too much. Nitrate (NO3-), on the other hand, is the social butterfly of nitrogen. It travels freely through the soil, readily available for plants.  The problem?  Sometimes the party gets a little too wild, and nitrate can leach out of the soil, leaving the plants high and dry. So, it's a trade-off. Ammonium is the easy option, but a bit of a homebody. Nitrate is the socialite, readily available but prone to ditching the party early. In most fields, nitrate wins because it's more abundant.  Think of it as the buffet option, with plenty of food but maybe not the most gourmet selection. Here's what else you should know: some clever scientists are developing ways to slow down that nitrate party, keeping it in the soil longer.  It's like giving the party a chaperone!  This can help plants get the most out of the nitrogen feast.

So, the plant world isn't black and white.  It's all about finding the right balance between convenience and availability when it comes to nitrogen.

The Nitrogen Advantage: The Superpower Nutrient for Plants

Imagine a plant like a high-performance athlete. It needs the right fuel and building blocks to thrive. That's where nitrogen comes in – it's like the protein powder of the plant world, except way cooler! Most plant tissues are packed with 3-4% nitrogen, making it a champion compared to other nutrients.

Why is nitrogen such a superstar? Here's the breakdown:

  1. The Green Machine: Nitrogen is a key player in chlorophyll, the green pigment that lets plants capture sunlight and turn it into sugary goodness (photosynthesis). Without enough nitrogen, plants become pale and sickly, kind of like us when we skip too many veggies!

  2. Building Blocks of Life: Proteins are the building blocks of everything in a living thing, and plants are no exception. Nitrogen is a major component of amino acids, which are like tiny Legos that snap together to create these essential proteins. Without enough nitrogen, plants would be weak and floppy, unable to grow or fight off challenges.

  3. Energy on Demand: Ever heard of ATP? It's the energy currency that keeps cells going, and guess what? Nitrogen is a part of it! ATP acts like a tiny battery, storing and releasing energy for all the plant's processes. Without enough nitrogen, plants would be sluggish and struggle to perform even basic tasks.

  4. The Blueprint of Life:  DNA, the genetic code that tells a plant how to grow and reproduce, also relies heavily on nitrogen. Think of DNA as the instruction manual for building a plant. Without sufficient nitrogen, this manual would be incomplete, hindering the plant's ability to grow strong and pass on its genes.

The Nitrogen Hustle: How Plants Get Paid in the Soil

Plants are like athletes – they need the right fuel to grow big and strong. But unlike protein shakes, their main source of nitrogen isn't readily available. It's a locked-away treasure in the soil, existing in three main forms:

  1. Organic Nitrogen (The Big Stash): This makes up a whopping 95-99% of the soil's nitrogen! It's like a giant piggy bank filled with plant and animal leftovers, along with living microbes. Unfortunately, plants can't directly access it.

  2. Ammonium (NH₄⁺) - The Clingy Cousin: This form is slightly more plant-friendly. Imagine ammonium as a shy kid sticking to the soil's negatively charged surfaces (CEC) like Velcro. It's available, but not readily moving around the soil.

  3. Nitrate (NO₃⁻) - The Free Spirit: This is the real MVP for plants. Unlike ammonium, nitrate ions are negatively charged, so they don't stick to the soil. They freely roam the soil water, readily available for plants to absorb. Think of them as the "delivered to your doorstep" option for plant nutrition.

So, where does all this nitrogen come from? Here's the breakdown of the nitrogen cycle's income streams:

  1. Slow and Steady Wins the Race: Minerals in the soil slowly release nitrogen, but it's a small contribution. Think of it like a forgotten piggy bank – barely adds to the pot.

  2. Nitrogen Gas (N₂) - The Inert Investor: The atmosphere is full of nitrogen gas, but it's useless to plants in its current form. It's like a massive, locked vault – plants can't access the funds!

  3. Lightning Strikes! (Free Nitrogen!): Thunderstorms actually convert some atmospheric nitrogen into usable forms. It's like a small windfall, but not a reliable income source (around 20 lbs of nitrogen per acre per year).

  4. Legume Buddies (The Nitrogen Fixers): Here's the real game-changer! Bacteria like Rhizobia form a symbiotic relationship with legumes (like peas and beans). They "fix" atmospheric nitrogen into usable forms, essentially giving the legumes a hefty nitrogen boost. It's like having a personal financial advisor who unlocks the vault and brings in big bucks (over 100 lbs of nitrogen per acre per year in some cases!).

Different Forms of Nitrogen

But unlike chugging a protein shake, plants getting their nitrogen fix isn't always straightforward. Here's the story of how plants get the nitrogen they need, from surprising natural sources to human-made innovations!

Nature's Nitrogen Network:

  • The Big Stash: Decomposing Champs: Most of the Earth's nitrogen is locked away in the atmosphere, making up about 78% of the air we breathe. Plants can't use it directly, but some amazing players in the soil step in – decomposers! These tiny microbes break down dead plants and animals, releasing nitrogen in a form usable by plants (ammonium). It's like a giant recycling plant turning waste into fertilizer!

  • Lightning Strikes! Nature's Power Plant: Believe it or not, lightning acts as a giant nitrogen fixer in the sky! The high energy from a lightning bolt splits nitrogen molecules in the air, turning them into a reactive form that can combine with other elements in the atmosphere. Eventually, these compounds get deposited in the soil, acting as a natural nitrogen fertilizer.

  • Legume Love: The Root Party Trick: Plants called legumes (like peas, beans, and lentils) have a secret weapon – tiny superheroes called rhizobia bacteria living in nodules on their roots. These bacteria have a special talent: they can take nitrogen directly from the air and convert it into a usable form for both the plant and themselves! It's a win-win partnership – the legume gets nitrogen, and the bacteria get a cozy home and food from the plant.

Human-Made Help: The Haber-Bosch Process

While nature has its ways, sometimes we need a little extra help. That's where the Haber-Bosch process comes in. This ingenious invention, developed in the early 1900s, allows us to create nitrogen fertilizer in factories. Here's the gist:

  • High Pressure, High Stakes: The process combines nitrogen from the air (remember, it's mostly nitrogen!) with hydrogen (often from natural gas) under high pressure and temperature with a special catalyst. This creates ammonia (NH₃), a key ingredient in many nitrogen fertilizers.

  • Energy Intensive:  Unfortunately, there's no free lunch. The Haber-Bosch process requires a significant amount of energy, mainly natural gas. This is why scientists are constantly researching ways to make the process more efficient and sustainable.

Urea: The All-Purpose Fertilizer Player

Urea (CO(NH₂)₂), another common nitrogen fertilizer, is often derived from ammonia produced by the Haber-Bosch process. It's a versatile option because it can be applied directly to the soil or dissolved in water to create a liquid fertilizer.

Compost: Nature's Slow Cooker

Compost isn't just a haven for happy worms – it's also a treasure trove of nitrogen! As organic materials like food scraps and yard waste decompose, they release nitrogen (along with other nutrients) in a slow and steady stream. It's like a natural slow cooker for nutrients, perfect for long-term plant nourishment.

The Nitrogen Cycle: A Soil Symphony with High Stakes

Imagine the soil as a bustling marketplace for plants. Nitrogen, a crucial nutrient, is like the currency they need to thrive. But this currency doesn't stay put – it undergoes a fascinating series of transformations called the nitrogen cycle. Here's the breakdown:

The Great Transformation:

The heart of the cycle is the conversion between organic and inorganic nitrogen. Microbes, the tiny workers of the soil, play a starring role. As they grow, they take up inorganic nitrogen (like ammonium and nitrate) and lock it away as organic nitrogen in their bodies – a process called immobilization. Think of it as microbes "hoarding" the currency.

Recycling and Release:

But the story doesn't end there. When these microbes die and decompose, other microbes step in as decomposers. They release the "hoarded" nitrogen back into the inorganic pool as ammonium, a process called mineralization. This is like recycling used currency back into circulation. The rate of this exchange depends on temperature and moisture – a warm and moist soil is a thriving marketplace for nitrogen exchange.

Nitrification: The Upward Shift:

Not all inorganic nitrogen is equal for plants. Ammonium isn't readily absorbed. Enter nitrification, a two-step process by which specialized bacteria convert ammonium to nitrate. Think of it as converting pennies (ammonium) into dollar bills (nitrate) – a much more valuable form for plants. But there's a catch – nitrification needs well-aerated soil, so waterlogged conditions can disrupt this conversion.

Losses in the System:

Unfortunately, the nitrogen cycle isn't perfect. There are ways this valuable currency can be lost:

  • Leaching: Nitrate, being highly soluble, can wash away with excess water, especially in coarse-textured soils. Imagine dollar bills getting swept down a drain!

  • Denitrification: When soils are saturated for long periods, oxygen gets scarce. Some microbes resort to "stealing" oxygen from nitrate, converting it back to unusable forms like nitrogen gas. It's like burning your dollar bills for warmth!

  • Volatilization: In high-pH soils, ammonium can lose a hydrogen ion and transform into ammonia gas, which escapes into the air. Think of some coins evaporating!

  • Crop Removal: When we harvest crops, we remove a portion of the nitrogen. However, the nitrogen in crop residues eventually gets decomposed and recycled back into the system.

The Great Nitrogen Detective Game: Why Test for Both Nitrate and Ammonium?

Ever wondered why detectives don't just look for one clue at a crime scene? It's the same with soil testing! Here's why checking for both nitrate (NO₃⁻) and ammonium (NH₄⁺) helps us crack the case of healthy plant growth.

Plant Food Puzzle: Plants need nitrogen to thrive, but the air is full of it (as N₂) and they can't use it directly! It's like having a locked treasure chest of fertilizer. Luckily, helpful bacteria act like tiny factories, converting N₂ into usable forms like nitrate and ammonium.

Picky Plant Eaters: But plants are picky eaters! They mainly prefer nitrate, with some settling for ammonium. Testing for both helps us understand the full menu of nitrogen options available.

Manure Mysteries: When we add manure, the nitrogen starts as a complex mix the plants can't use. It slowly breaks down into ammonium, then nitrate. Testing for both ammonium and nitrate helps us see how much nitrogen is readily available (ammonium) and how much is on its way (nitrate).

Fertilizer Frenzy: Some fertilizers go straight to ammonium, while others need to convert first. Testing for both shows the total nitrogen picture, not just what's immediately available.

The Great Nitrogen Conversion Caper: Sometimes, conditions like cold or wet soil can slow down the conversion of ammonium to nitrate. By testing for both, we can see if the nitrogen "factory" is working efficiently or if the plants need a little extra help.

The Takeaway: Testing for both nitrate and ammonium gives us a more complete picture of the nitrogen situation in the soil. It's like having more clues to solve the mystery of healthy plant growth!

Understanding the Cycle Matters:

By understanding the nitrogen cycle, farmers can make informed decisions about nutrient management. They can minimize losses and ensure there's enough "currency" flowing in the soil for healthy plant growth. It's a complex dance, but one that keeps the agricultural show going!

Nitrogen: The Fuel Gauge for Plant Growth

Plants are like high-performance athletes - they need the right fuel for optimal growth. And for them, nitrogen is the ultimate performance enhancer! But how exactly do plants get this crucial nutrient?

Picking the Right Nitrogen Form: Plants can absorb nitrogen in two main forms: ammonium (NH₄⁺) and nitrate (NO₃⁻). However, thanks to a process called nitrification happening in most agricultural soils, nitrate becomes the more popular choice for plants. Think of it like this: a plant's roots "drink" water, and the nitrate "hitchhikes" along for the ride, readily moving towards them.

Turning Fuel into Growth: Once inside the plant, the magic happens. Nitrate gets converted into a usable form (NH₂) and then incorporated into essential building blocks for the plant. This is why a healthy root system is crucial – the more roots, the more "straws" the plant has to "sip up" the nitrogen-rich water. In fact, plants with compacted soil around their roots can show signs of nitrogen deficiency even if there's plenty available!

Nitrogen: A Lifelong Need: Unlike us who might skip a meal occasionally, plants crave a steady stream of nitrogen throughout their lives. As the plant grows bigger, its demand for nitrogen increases – think of it like needing more fuel as your engine gets larger.

The Nitrogen Sweet Spot:  When a plant gets the perfect amount of nitrogen, it thrives! It grows rapidly, with lush, green foliage. Imagine a cornstalk reaching its full, majestic height, thanks to sufficient nitrogen.

Too Much of a Good Thing?  However, just like with any good thing, too much nitrogen can be detrimental. If a plant gets bombarded with excess nitrogen, it can grow too fast for its own good. It might be like a car with a faulty fuel gauge – the engine races, but the supporting structures (like cell walls) can't keep up. This can make the plant weak and susceptible to damage.

Understanding Nitrogen Needs: By understanding how plants absorb and use nitrogen, farmers can strike a delicate balance. They can ensure their crops have enough of this vital nutrient for healthy growth, without overdoing it and creating weak, vulnerable plants. It's all about finding the nitrogen sweet spot for optimal agricultural performance!

Decoding Nitrogen: A Fertilizer Management Masterclass

Nitrogen – the lifeblood of plants! But managing it effectively in fertilizers can be a tricky business. Here's a breakdown to help you become a fertilizer master:

Finding the Nitrogen Sweet Spot:

The amount of nitrogen fertilizer a crop needs depends on several factors:

  • The Crop: Different crops have different appetites for nitrogen. A cornfield needs more than your backyard tomatoes.

  • Yield Goals: Aiming for a record-breaking harvest? You'll need more nitrogen fuel for the extra growth.

  • Soil's Nitrogen Reserves: Not all the nitrogen comes from fertilizer. The soil itself might have some stored nitrogen from previous crops or organic matter.

Taking Nitrogen Credits:

Farmers use a system called "nitrogen credits" to account for the soil's contribution. Think of it like a pre-paid nitrogen card – corn following alfalfa (a nitrogen-fixing legume) has a higher credit than corn following corn itself. Similarly, applying manure adds to the soil's nitrogen "balance."

Testing for Nitrogen:

Soil testing is becoming a popular way to determine the exact amount of nitrogen needed, instead of relying solely on credits. It's like checking the soil's "nitrogen bank account" before making a fertilizer deposit.

Placement Matters:

Just like us, plants can't reach for nutrients that are far away. Fertilizer placement is crucial for efficient uptake. Broadcasting (spreading evenly) works well, but for row crops like corn, banding (placing fertilizer near the rows) can be just as effective.

Moisture Matters:

Think of moist soil as a delicious buffet for plant roots. Placing fertilizer below the surface, especially during dry periods, ensures easier access to this nitrogen feast.

Minimizing Losses:

Nitrogen can escape from the soil in several ways:

  • Volatilization: This is like nitrogen "evaporating" from the surface. Urea fertilizers are particularly prone to this, so incorporation (mixing them into the soil) helps.

  • Leaching: Heavy rain can wash away nitrate (a form of nitrogen) before plants can use it. Split applications (applying fertilizer in stages) can minimize this loss.

  • Denitrification: When soils are waterlogged for extended periods, some microbes "steal" oxygen from nitrate, rendering it unusable by plants. Avoiding fall applications on poorly drained soils helps prevent this.

Timing is Key:

Delivering nitrogen when plants need it most is crucial. Wheat needs a nitrogen boost in spring and early summer, while corn thrives on it during midsummer.

Starter Nitrogen:

A small amount of nitrogen applied early in the season gives seedlings a quick energy boost while they establish their root system and access the main nitrogen source.

The Takeaway:

By understanding nitrogen cycles, fertilizer types, placement strategies, and application timing, farmers can become nitrogen management masters! They can ensure their crops get the right amount of nitrogen for optimal growth, while minimizing losses and protecting the environment. It's all about finding the nitrogen sweet spot for a bountiful harvest!

So, next time you bite into a plump, juicy fruit or a hearty whole grain, take a moment to appreciate the unseen hero – nitrogen. It's the silent partner working tirelessly behind the scenes to ensure bountiful harvests and a nutritious food supply. When we see a vibrant, flourishing plant, remember the power of nitrogen! It's the invisible force that fuels plant growth, making it a superhero nutrient for the entire food chain.


GroEat Farm, LLC is a small, sustainable family farm located in Bozeman, Montana.  We’re located in the beautiful Hyalite foothills, below the Gallatin Mountain Range.  The hardneck varieties that grow at our farm (Ophioscorodon) flourish here, due to the combination of the cold winters, temperate summers, moist spring, and the dynamic alluvial soils, washed down from the Gallatin Range (comprised of Archean metamorphics, Paleozoic and Mesozoic sedimentary rocks, and Eocene volcanics).  Not only are the GroEat Hardneck garlic healthy and beautiful, the flavor’s are robust and delicate.


Our mission at GroEat Farm, LLC is to grow premium hardneck garlic, preserve garlic varieties for the future (through propagation), and to provide others with the opportunity to grow garlic from our seed.   We help home gardeners, chefs, small-scale commercial growers, gardeners, plant nurseries, and anyone else looking for better hardneck garlic.  We are continuing a very long tradition of growing quality gourmet and seed hardneck garlic.   

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