In high school, I needed community service hours to graduate and had a chance through my ecology class to score some. My assignment was to build a compost pile in exchange for 20hrs or something close to that, and so I set to work digging a hole at the bottom of my parent’s yard.
A few days later, I had a soaking wet pit with a whole lot of kitchen waste, a couple of leaves, and piles of grass all mixed together with a tiny bit of soil. I snapped a few pictures with a disposable camera and was off to a photo kiosk to get it developed.
Little did I know at the time I had not created a compost pile but instead a noxious biological weapon that was about to ruin my weekend. It turns out my pile had way too much nitrogen, and when the temperature rose, and more moisture was added, the ammonia smell was abominable.
Read below to learn about the right amount of nitrogen and the materials that have the most!
What compostables have the most nitrogen?
To understand what compostables have the most nitrogen, you can look at the color and stage of decomposition. In general, any material that is green and moist will contain higher levels of nitrogen than dry, brown composting matter. Common home and yard waste such as grass clippings, plant cuttings (floral and garden crops), coffee grounds, fruit and vegetable scraps, and manure contain high levels of nitrogen.
What is Nitrogen in Compost?
Nitrogen is one of the two main elements that need to be considered when building a compost pile. Along with carbon, you get what is commonly referred to as the C:N ratio. This ratio, similar to the ratios used when baking, can have a lot of flexibility but offers the best guidelines for producing a finished compost your plants will love.
When starting a compost pile, the goal is to achieve a ratio of 30:1. Then, through the magic of composting, within anywhere from 14 days (Berkley Method) to one year (pile and forget), you will have 10:1 compost and beautiful organic materials needed for bountiful plant growth.
The composting process fuels its own decay through off-gassing carbon. As a compost pile heats up and breaks down, the nitrogen should stay relatively stable as carbons in the compost materials loosen their bonds and combine with oxygen to form CO². With enough heat, water, microbes, and time you will be left with a third of the carbon you started with and practically the same amount of nitrogen.
Why Does the Correct Amount of Nitrogen Matter?
The correct amount of nitrogen matters greatly if you want a sweet-smelling compost pile that is ready for use by the next planting season. If too much or too little nitrogen is added, then you will have a tough time getting the desired outcome, and the results can be harmful to plants and downright unpleasant to be around.
Too Much Nitrogen:
There are a few things that can go wrong if you add too much nitrogen and not enough carbon to your pile.
- Ammonia Smell – One of the quickest ways to know you missed the mark with your ratio is a very unpleasant smell. The odor can become quite strong, and often when you flip a pile; you can be caught off-guard by the stench. You can be sure this smell will attract pests and piss off your friends and family.
- Potential to Spontaneously Combust – Did you know nitrogen is a common ingredient in explosives? Well, it is! And if you mix a combustible material with dry leaves and other kindling and then expose it to high heat and oxygen, what do you get? Fire! Too much nitrogen can lead to a pile smoking and catching on fire. Obviously, this should be avoided at all costs.
- Burn New Seedlings – If somehow adding too much nitrogen did not result in a fire or a noxious odor, there is still the potential harm to plants when applied in the spring. The high levels of nitrogen that did not get diluted or broken down can be too hot for new grass or garden seedlings. When they sprout, they may turn bright yellow and wither from nitrogen burn.
Too little Nitrogen:
Without enough nitrogen, your compost may not be able to achieve the correct results. If this happens, the compost you produce may do little more than commercial dirt to aid your new lawn’s growth.
- No Heat – While the heat from the sun wakes up the microbes and chemical processes needed for compost to get started, a lot of the action comes from the breaking down of organic materials. If all you add to the compost is dead, dry, brown leaves and twigs, then at the end of a year, you will still only have dead leaves and twigs.
- No Nutrients – If you check the fertilizer packages, you will see NPK. Notice how there is no C there. If you want plants to grow, you need nitrogen levels to be adequate at the end of the composting process. Without the high levels of nitrogen, your compost will only be as useful as garden-variety soil, and you will still need to purchase additives. What a waste!
How can I add nitrogen to my compost pile?
Now, you’re probably wondering how can you add nitrogen to your compost pile. There are several ways to do this, and each one has its own advantages and disadvantages. The most important questions to consider are how much nitrogen is needed and at what stage is the compost currently undergoing.
If you need to increase your nitrogen by a lot and the compost is already on its way to being complete, you should add nitrogen in the form of liquids or powders. Some easy ways to add nitrogen via liquid is to find pond or aquarium water. This will have nitrogen in it as well as highly evolved microbes that will go to town on your pile. Additionally, powder additives like bone, blood, or gluten/soy meal can be used in a pinch.
You may, however, find yourself with no resources to buy additives but lots of time. In that case, you should collect all the leafy, green plant material you can find and shred it. Shredded material breaks down faster than large chunks of organic material.
You can also add manure from different animals at the beginning of your composting. Rabbit, chicken, and horse manure are the most common for yard composts. You will want the compost to age for around 6 months if using raw animal manure.
What compost materials have nitrogen?
Nitrogen is abundant and found in pretty much all living and dying things. But just because it is all around us doesn’t mean it is always accessible. Selecting the right materials that will unlock nitrogen for the plants through the composting process is the aim here.
There are many common and zero-cost ways to accumulate large amounts of nitrogen-rich compostable materials. A quick look around your home and yard should yield a few ready sources. If you need even more, neighbors and co-workers may be able to collect some nitrogen caches as well.
Around the house, you can find old flowers and new flower cuttings. You can also collect all of your fruit peels and vegetable scraps. It is really common to have either used coffee grounds or tea bags available, and these are also excellent nitrogen-rich additions for a thriving compost.
If you wander out into the yard, you are likely to find grass cuttings, pulled weeds, and plant prunings that can be added to your pile. You may also have access to animal bedding and nesting, which can add nitrogen and other micronutrients. Of course, if you have any pet rabbits, you have a plant miracle pellet on demand, so toss that in the compost as well.
Common Nitrogen Sources and Ratios
Discovering materials high in nitrogen is only part of the equation. It is important to know how much carbon to nitrogen each of these contributions has. With the correct combination of materials, you can achieve the desired ratios of 30:1 at the start and 10:1 at completion.
It is easiest to source materials that are already common and accessible to you, even if it means the ratios won’t be exact. If you cannot sustain the pile, it is possible that you will have problems, so have your nitrogen-rich organic matter ready to go before you start the process.
Carbon and water levels can be adjusted throughout the composting process to give you the best results, but the nitrogen levels are pretty fixed from the beginning. Make sure to save the nitrogen materials for a complete batch of compost before starting the process, or you will lose nitrogen before you even begin.
Find out what compost materials have nitrogen and the ratio to carbon in the tables below:
Common Home and Yard Waste Nitrogen Sources
| Material | C/N Ratio |
| Grass clippings | 15-25:1 |
| Plant cuttings | 15-20:1 |
| Coffee grounds | 20:1 |
| Vegetable scraps | 15-20:1 |
| Manure | 5-25:1 |
Easily-Found Quick Additive Nitrogen Sources
| Material | C/N Ratio |
| Bone meal | 3-4:1 |
| Blood meal | 4:1 |
| Corn gluten meal | 20:1 |