Earth Friendly Ways for Adding Carbon To Soil

I’m going to go ahead and make the assumption that you have found yourself on this page due to previous knowledge that your soil is carbon deficient. So before I dive too deep into the various ways you can naturally combat that deficiency, I’d like to commend you for getting out there and testing your soil.

If you haven’t tested your soil or taken other measures to determine what needs to be done to amend your soil, we recommend starting by taking a sample of your soil to a soil testing lab or local extension office in your area. Alternatively, you can order soil test kits online or pick them up in many farm & garden stores. 

Ensuring the right amount of carbon is present in the soil you are currently using or plan on using to grow trees, shrubs, produce, grasses, and other plants is a critical step in achieving optimal health for your plants and the environment as a whole. Keeping carbon in the soil can be an effective way of controlling weeds, leaving more nutrients for your plants, and keeping harmful carbon dioxide from entering the air. 

Most soil types need to be amended year after year to replenish important resources utilized by previous plantings and released upon their decease or other disruptions in the soil. Not all cases of carbon deficiency are the same, however. It's important to consider the various ways for adding carbon to your soil because there are several and not all of them will be right for your planting goals. In this article, we will look at some of the options for increasing carbon levels to help you determine which one is right for you and the soil you are looking to improve. 

While the below mentioned methods are wonderful ways for reintroducing carbon into the soil; it is also important to stress that soil and the root systems that reside in it will ultimately release more carbon dioxide into the air when disturbed. This means that unnecessary tilling could actually counteract other efforts taken to improve the health of soil. So, whichever method or methods you choos to add carbon to your soil, try to remain minimalistic when it comes to disturbing the soil. 

How To Add Carbon To Soil

Don’t plant the same thing in the same spot year after year. 

You know those stripes you see in fields as you fly over them in an airplane? They aren’t put there simply for aesthetic pleasure. Farmers have been using the practice of crop rotation since the times of ancient Rome to improve biodiversity, combat pests, and maintain the overall health of soil and plants. This practice isn’t solely for crops like grains and legumes, however. The same benefits can be experienced by avoiding planting the same plant type in the same spot from year to year, no matter what you are growing. 

Even many farmers aren’t getting it right though. Avoiding planting the same crop in a field back-to-back years may help the weed and pest situation, but it is doing very little to reintroduce essential nutrients back into the earth if those fields are stripped and left bare.

The same is true for landscape plants and fruit and vegetable gardens. Rather than leave those fields and gardens empty, plant something completely different that replenishes nutrients used up by the previous crop. Not only will your soil be healthier overall, “when combined with no-till or low-till practices, it  can have a significant impact on carbon sequestration with positive impacts on reducing the rate of climate change”.

Utilize mulch, fallen leaves, and other decaying plant matter to cover soil.

Exposed soil will leach carbon into the air, so it’s best to keep it covered in times when nothing is growing there (ie: winter months). In some instances, keeping it covered can be as simple as allowing the leaves to remain where they have fallen or waiting until spring to clean up the previous year’s plant debris before replanting. If you don’t have enough trees or the neighbors frown upon unraked leaves, you can always opt to add a layer of mulch. 

For larger areas, and even garden spaces, cover crops can also be used to keep the soil healthy. Cover crops are planted in the fall to maintain soil-health throughout the colder months, absorbing nutrients that might otherwise be leached from the soil with winter moisture and keeping erosion at bay. Some of the most common cover crops are grasses, legumes, and brassicas. Personally, I love using kale because it also gives me an early spring harvest of Napini, or kale rabe, which is absolutely delicious when roasted. 

Other plants that can be overwintered and enjoyed in the spring include a long list of root vegetables, including carrots, onions, garlic, beets, and radishes. Though it is important to note that they might not do well in soils that aren’t well-drained or in areas with excessive rainfall. 

Plant more trees, shrubs, and other perennials.

Remember that diagram of the tree you were shown in elementary school—the one that showed the cycle of trees absorbing carbon dioxide through photosynthesis and releasing the oxygen into the air for us to breath. That explains where the O₂ part of the CO₂ went, but what about the C (the carbon)? Well, just as humans breath, so do trees and other plants, so some of it is released back into the air but much more of it is essentially pushed through the plant, down to the roots, where it secretes it into the soil. Once it has been delivered back into the soil, it is able to “feed” microbes, keeping them alive and ready to break down other decaying plant matter that would otherwise be excreting more CO₂ back into the air. 

This being the case, planting more permanent plants will ensure long-term carbon management, not only reducing CO₂ emissions from disturbing the soil through tilling, but also by absorbing what is released into the air and bringing it back to the soil and then further preparing the microorganisms in that soil to combat further emissions.

Utilize biochar to amend soil.

Biochar is a type of charcoal. It is produced by burning organic materials with limited amounts of oxygen present. Indigenous peoples of Amazonia have been using biochar for thousands of years, which has led to their soils being some of the richest on earth. Biochar, when mixed into the earth, not only distributes nutrients and helps to balance the pH levels, it holds carbon in the soil longer due to its density and the extended period of time it takes to break down. It ”doesn't break down like other organic soil amendments and resists chemical and microbial degradation”. 

Because biochar is made using limited oxygen, the carbon in decaying plant matter is not enabled to mix with the O₂ element to create CO₂, thus it keeps carbon dioxide from entering the atmosphere. Instead, it remains in a new compacted form (ie: biochar), where it will remain when buried in the earth, allowing beneficial organisms to thrive, feed plants, and process other decaying plant matter over the course of many years. 

If you are interested in using biochar, there are plenty of tutorials available online that explain the process. Or, if you want to get started by adding biochar to your soil right away and benefiting from the longterm effects, it can also be purchased at just about any farm & garden supply store. 

Because disturbances of the earths surface will lead to the sequestiaring of carbon from the soil, above ground watering can actually exacerbate carbon release and increase the amount of carbon dioxide in the atmosphere. With underground watering devices, like Root Quencher, you can water your plants with a clear conscience, knowing you are helping the planet and the health of your soil by minimizing water usage and keeping carbon from escaping the earth.