Cycling with a Lightning ⚡️ 🌧️ The Nitrogen Cycle 🌱 ♻️

We all need to breathe in order to get oxygen for our bodies 🫁; animals have the same need 🐾. But what about plants? They also need to breathe 🌿, but instead of oxygen, they breathe another gas in the air—do you remember what this gas is called? ❓ We have discovered that each leaf is a hard-working food factory 🍃, using water and minerals that the roots deliver 💧🪴, and a gas called carbon dioxide from the air 🌬️. With the help of the sun, they make their own food☀️, and the oxygen they don’t need, they give back to the air. This goes on and on, all over the world. 🌍

But there is another gas that plants need in order to grow. This time, the problem is that they can’t take it simply from the air like carbon dioxide. They need helpers, which we will reveal in this story today—and we will see how those helpers help plants take this gas hidden in the air. 🌬️✨ This gas is made from two nitrogen atoms joined together.

First, the sky helps. During a storm, lightning flashes and gives the air a burst of energy ⚡️. The air around us is full of nitrogen gas (N₂). Plants need nitrogen, but they can’t use N₂ directly. So lightning helps change some of that nitrogen into plant-ready bits called nitrate. Nitrate is nitrogen plus three oxygens (NO₃⁻)—lightning helps the transformation, the “fastening.” Roots can now sip these just like a drink from the soil. 🌧️🧪

But, the roots of certain plants help also help transforming nitrogen . If you can zoom into the roots of beans, peas, or any other legumes 🫘 we can find tiny bumps on the roots called nodules. (nodule means “little knot”). Inside each nodule live helpful bacteria. The plant shares sugars with these bacteria, and the bacteria take nitrogen gasfrom the air spaces in the soil and turn it into plant food the roots can use—first ammonium, then nitrite (NO₂⁻)—nitrogen with two oxygen “partners”—and finally nitrate (NO₃⁻)—nitrogen with three oxygen “partners.” This is a teamwork story—living together so both the plant and the bacteria benefit. Sometimes the nodules look a little pink inside when they’re busy transforming nitrogen . 🦠

There is also the quiet, steady help from the compost corner. 🍂 Old leaves and peels don’t disappear just like that; the decomposers like bacteria, fungi, and tiny critters—break them down into early nitrogen forms with a strong smell at first (ammonia). In airy soil, other bacteria quickly change that ammonia into gentler, plant-ready forms: ammonia → nitrite → nitrate. If we put a hand on the compost, it can feel a little warm; a week later the sharp smell fades as more of the ready-to-drink niTRAte appears in the soil water. 🪱✨

Farmers all over the world use compost to enrich their soil—now you know why compost is so special. It helps plants grow big and strong, and helps fruits and veggies be rich in vitamins and minerals the soil provides so generously to the plant’s food factory. Plants pull these tiny bits through their special root hairs and, together with water and sunlight, build new leaves, flowers, and seeds in their fruits. 🌱☀️

As animals nibble the leaves (we eat leaves too—salads! 🥗), the nitrogen becomes part of them as well. When plants and animals leave scraps or come to the end of life, the decomposers return the nitrogen to the soil again. And when the soil is very wet—those soggy patches after heavy rain—another group of helping bacteria uses the plant-ready bits and sends nitrogen back to the sky as nitrogen gas (N₂ : two nitrogen atoms joined together). That keeps the world in balance. 🌊🫧➡️🌬️ Sometimes we can even see tiny bubbles in the puddles where this is happening.

So, right here in our garden, we can notice a gentle circle: storms help, beans help, compost helps—three ways nitrogen comes into the soil—and in very wet places, some nitrogen goes back to the sky. Air → soil → plant (and animal) → soil → air again. ♻️

📍Let’s tell the whole story with our chart. 🌧️🌱
(Point to the round N₂ in the air bubble.)
Most of the air is nitrogen gas, N₂—plants can’t use it yet. 🌬️ (Slide your finger to the storm cloud and rain.) During storms, lightning gives the air a burst of energy ⚡️. Some nitrogen changes and washes down in the rain as nitrates.NO₃⁻ ( Lightning creates enough energy so that 3 oxygen atoms combine with every nitrogen atom and create something new that is called nitrate NO₃⁻.) That’s one way plant food reaches the soil. 🌧️

(Point to the legume roots with nodules.)
On the roots of beans, peas, and clover, tiny nodules hold helpful bacteria. The plant shares sugars, and the bacteria change nitrogen into forms the roots can use—another way plant food arrives. 🫘🦠

(Move to leaves/animal/decomposition area.)
When plants grow, they use nitrogen to make proteins in leaves and stems. 🌿 Animals eat the plants and get nitrogen too. When leaves drop or animals leave scraps, decomposers—bacteria, fungi, earthworms—break them down into ammonia (NH₃). In airy soil, it changes step by step to nitrite (NO₂⁻) and then nitrate (NO₃⁻). 🍂🪱

(Point the wet ground/denitrification and follow the arrow returning to the air.)
See this long word dentrification, it comes from latin prefic de- meaning removal, and the noun nitrification, so it means removal of nitrates from the soil. In soggy spots, like bogs or very big puddles on big grassy fields which take a week to dry out, other bacteria send nitrogen back to the sky as N₂. Sometimes there are tiny bubbles—that’s our clue. 🌊🫧➡️🌬️

(Trace the big loop with your finger.)
So our garden keeps the balance: air → soil → plant (and animal) → soil → air again. ♻️

I wonder…

• Can too much nitrite harm plants? Where might nitrite pile up—airy beds or soggy spots? What could we do to keep nitrite from building up? 🔎💧

• Can plants absorb nitrite? (We know they mainly absorb nitrate and ammonium.)

• Do all plants grow nodules? If not, how do plants without nodules get the nitrogen they need from the soil? 🌱

• How long does a banana peel (and other compost material) take to become plant food we can measure? 🍌🧪

♻️Possible follow-up explorations♻️

• Memory game with the chart:

  “Show me three ways nitrogen comes into the soil.” (Children point: storm cloud, legume nodules, decomposers/compost.)

  “Show me one way it goes back to the air.” (Children point: denitrification arrow.)

• Soggy-patch observation : After rain, check the wet spot—do we see bubbles? That’s a clue denitrification might be happening. 👀🫧

• Legume root peek: Gently choose one small edge legume (bean, pea, or clover), loosen soil, lift carefully, and swish roots in a bowl of water to find nodules (the little bumps). Return and water. 🫘🌱💧

• Further observations & nodule dissection (with adult help): Slice one nodule to peek inside; pink or reddishmeans it’s busy, thanks to leghemoglobin, which helps the bacteria work with just the right amount of oxygen. 🔬

• Nodule art: Make a quick sketch, count nodules, and, if you have extra seedlings from thinning, dissect a few nodules and compare colors—pale vs. pink. Wonder which roots were most active today. 📝🎨

Guide note : Important Prerequisites

• Impressionistic Story: Roots — roots as water/mineral seekers and anchors 🌱

• Needs of Plants — sunlight, water, air (CO₂), minerals, and space ☀️💧🌬️🪨

• Impressionistic Story: The Food Factory — leaves make food; stomata, sunlight, chlorophyll 🍃

• Chart of Interdependencies — living + nonliving networks, setting the “we’re all connected” lens 🕸️

With Montessori joy,

Vanina 😊