In previous articles, we have mentioned the importance of “carbon to nitrogen ratio” in compost production many times, but there are still many readers who are still full of doubts about the concept of “carbon to nitrogen ratio” and how to operate it. Now we will come. Discuss this issue with you.
First, the “carbon to nitrogen ratio” is the ratio of carbon to nitrogen. There are a variety of elements in compost material, and carbon and nitrogen are two of the most important:
Carbon is a substance that can provide energy for microorganisms, generally, carbohydrates, such as brown sugar, molasses, starch (corn flour), etc., are all “carbon sources”, and straw, wheat straw, and other straws can also be understood as “carbon sources”.
Nitrogen can increase nitrogen for the growth of microorganisms. What is rich in nitrogen? Urea, amino acids, chicken manure (food is high-protein feed), etc. Generally speaking, the materials we ferment are mainly nitrogen sources, and then we appropriately add “carbon sources” as needed to adjust the carbon to nitrogen ratio.
The difficulty of composting lies in how to control the carbon-nitrogen ratio within a reasonable range. Therefore, when adding compost materials, whether using weight or other units of measurement, various compost materials should be converted into equivalent units of measurement.
In the composting process, the moisture content of about 60% is most conducive to microbial decomposition, although the carbon-nitrogen ratio of food waste is close to 20:1, but their water content may be between 85-95%. so. It is usually necessary to add brown materials to the kitchen waste, the brown material can suck up excess moisture.The compost windrow pile must be turned over by thecompost turnerfor a period of time to encourage airflow, otherwise, the compost might stink. If the compost material is very wet, move towards a carbon to nitrogen ratio of 40:1. If the compost material is already close to 60% moisture, it will soon be able to rely on the perfect ratio of 30:1.
Now, we will introduce you to the most comprehensive carbon-nitrogen ratios of composting materials. You can adjust the number of famous materials according to the composting materials you can use and combine the above-mentioned measurement methods to make the carbon-nitrogen ratios to the perfect range.
These ratios are based on averages and actual C: N, there may be some variation in the actual process, however, these are still a very good way to control the carbon and nitrogen in your compost when you are composting.
| Carbon to nitrogen ratio of commonly used brown materials | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Shredded cardboard | 350 | 350 | 1 |
| Hardwoodbark | 223 | 223 | 1 |
| Hardwoodchips | 560 | 560 | 1 |
| Dried leaves | 60 | 60 | 1 |
| Green leaves | 45 | 45 | 1 |
| Newspaper | 450 | 450 | 1 |
| Pineneedles | 80 | 80 | 1 |
| Sawdust | 325 | 325 | 1 |
| Cork bark | 496 | 496 | 1 |
| Cork chips | 641 | 641 | 1 |
| Oat straw | 60 | 60 | 1 |
| Rice straw | 120 | 120 | 1 |
| Fine wood chips | 400 | 400 | 1 |
| Covered plants | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Alfalfa | 12 | 12 | 1 |
| Ryegrass | 26 | 26 | 1 |
| Buckwheat | 34 | 34 | 1 |
| Clover | 23 | 23 | 1 |
| Cowpeas | 21 | 21 | 1 |
| Millet | 44 | 44 | 1 |
| Chinese milk vetch | 11 | 11 | 1 |
| Leaf mustard | 26 | 26 | 1 |
| Pennisetum | 50 | 50 | 1 |
| Soybeans | 20 | 20 | 1 |
| Sudangrass | 44 | 44 | 1 |
| Winter wheat | 14 | 14 | 1 |
| Kitchen waste | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Plant ash | 25 | 25 | 1 |
| Coffeegrounds | 20 | 20 | 1 |
| Gardening waste(dead branches) | 30 | 30 | 1 |
| Mowed grass | 20 | 20 | 1 |
| Kitchen rubbish | 20 | 20 | 1 |
| Fresh vegetable leaves | 37 | 37 | 1 |
| Tissue | 110 | 110 | 1 |
| Pruned shrubs | 53 | 53 | 1 |
| Toilet paper | 70 | 70 | 1 |
| Abandoned canned tomato | 11 | 11 | 1 |
| Pruned tree branches | 16 | 16 | 1 |
| Dry weeds | 20 | 20 | 1 |
| Fresh weeds | 10 | 10 | 1 |
| Other plant-based composting materials | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Apple pomace | 13 | 13 | 1 |
| Banana/Banana leaf | 25 | 25 | 1 |
| Coconut shell | 180 | 180 | 1 |
| Corn cob | 80 | 80 | 1 |
| Corn stalks | 75 | 75 | 1 |
| Fruit scraps | 35 | 35 | 1 |
| Grape pomace | 65 | 65 | 1 |
| Grapevine | 80 | 80 | 1 |
| Dry grass | 40 | 40 | 1 |
| Dry legumes plants | 20 | 20 | 1 |
| Pods | 30 | 30 | 1 |
| Olive shell | 30 | 30 | 1 |
| Rice husk | 121 | 121 | 1 |
| Peanut shells | 35 | 35 | 1 |
| Leafy vegetable waste | 10 | 10 | 1 |
| Starchy vegetable waste | 15 | 15 | 1 |
| Animal manure | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Chicken manure | 6 | 6 | 1 |
| Cowmanure | 15 | 15 | 1 |
| Goat manure | 11 | 11 | 1 |
| Horse manure | 30 | 30 | 1 |
| Human manure | 7 | 7 | 1 |
| Pig manure | 14 | 14 | 1 |
| Rabbit manure | 12 | 12 | 1 |
| Sheep manure | 15 | 15 | 1 |
| Urine | 0.8 | 0.8 | 1 |
| Other materials | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Crab/lobster droppings | 5 | 5 | 1 |
| Fish droppings | 5 | 5 | 1 |
| Lumber mill waste | 170 | 170 | 1 |
| Seaweed | 10 | 10 | 1 |
| Grain residue(big brewery) | 12 | 12 | 1 |
| Grain residue(microbrewery) | 15 | 15 | 1 |
| Water hyacinth | 25 | 25 | 1 |
| Composting catalyst | |||
| Material | C/N ratio | Carbon content | Nitrogen content |
| Blood powder | 14 | 14 | 1 |
| Bone powder | 7 | 7 | 1 |
| Cotton/soybean meal | 7 | 7 | 1 |
Blood powder is a powder formed from the drying of animal blood. Blood powder is mainly used to increase the content of nitrogen cables in the soil, making plants grow denser and green vegetables more “green”. Contrary to bone powder, blood powder can reduce the pH of the soil and make the soil acidic. The soil is very beneficial for plants.
The role of blood powder and bone powder They have a good effect on soil improvement, and wrong fertilization will not burn your plants. If the soil is acidic, use bone meal to increase the content of phosphorus and calcium, making the soil alkaline, It is suitable for flowering and fruit plants. If the soil is alkaline, use blood powder to increase the nitrogen content and make the soil acidic. It is suitable for leafy plants. In short, adding the above two to the compost is good for composting.
How to calculate
According to the carbon-nitrogen ratio of various materials given in the above list, combined with the materials used in composting, count the total number of various composting materials, calculate the total carbon content, and then divide by the total number of parts to make This number should be between 20 and 40.
An example to illustrate how the carbon to nitrogen ratio is calculated:
Assuming that there are 8 tons of cow dung and wheat straw as an auxiliary material, how much wheat straw do we need to add to make the carbon-nitrogen ratio of the total material reach 30:1?
We looked up the table and found that the carbon-nitrogen ratio of cow dung is 15:1, the carbon-nitrogen ratio of wheat straw is 60:1, and the carbon-nitrogen ratio of the two is 4:1, so we only need to put the amount of wheat straw into 1/4 of the cow dung amount. Yes, that is, 2 tons of wheat straw.
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Post time: Jul-07-2022