2022 Life Cycle Assessment: Calculating the Emissions of our Indoor Potting Mix

Soil Life Cycle Assessment

INTRODUCTION

We’re on a mission to cultivate Earth Positivity by helping gardeners nurture plants and the planet. We try to make earth-friendly gardening as easy and understandable as possible, because we believe that individual choices can add up to make a big difference. To accomplish this, we’ve tested and perfected a new soil option that has been proven to pull carbon out of the atmosphere. 

Soil has an amazing ability to store atmospheric carbon. In fact, the Earth’s soil holds four times more carbon than its plants. However, as lifelong gardeners, we were frustrated and disappointed to realize that most mainstream soil products have a significant carbon footprint (we explain why later in this report). We knew there had to be a better way. So, we've specifically designed our products from the ground up to be better for your plants and better for the planet.

To accomplish our mission to help rebalance the carbon cycle, we’ve committed to making the most sustainable products possible.  Our goal is to minimize our carbon footprint from the get-go, and lay a climate centered foundation to keep us poised for smart growth as we scale. Before we can work to reduce our impact, we have to fully understand what that impact is, and identify opportunities to reduce emissions or waste throughout our supply chain. This is the first step in a continuous effort to improve and minimize our environmental impact.  

That’s why we’ve conducted a Life Cycle Analysis (LCA) of our primary product, our Indoor Potting Mix. A Life Cycle Analysis is a survey of the emissions and waste created when a single unit of a product is made. We calculate the carbon impact incurred during each step of the product’s “life cycle.” The life cycle begins the moment a product’s raw materials are taken from the earth, encompasses every step of its creation and distribution throughout the supply chain, and ends when our customers use the item and discard the packaging. 

In accordance with standard LCA methodology, we’ve measured the net emissions created across the following 5 key stages: 

Lifecycle Assessment Stages

For this LCA, our impact is measured in terms of Carbon Emissions because this best describes the total amount of Carbon Dioxide (CO2) emitted throughout our product’s life cycle. You will see this listed as CO2 eq., or the equivalent emissions in kilograms of CO2

DATA SOURCES

We’ve collected data from a variety of sources to measure the carbon impacts of our Indoor Potting Mix for each component, throughout all phases of the product life cycle. 

To determine the net carbon impact of producing biochar, a key ingredient in our Potting Mix, we surveyed academic studies which measured both the emissions and sequestration of carbon from biochar production. Specifically, we relied on a 2009 Cornell Study that we felt was representative for a few reasons: 1) its authors surveyed the results of multiple other studies using a systems level methodology, 2) they used a conservative approach when concluding net carbon sequestration by taking into account a wide scope of emissions , and 3) the study itself has been cited a relatively high amount of times. For all these reasons, we felt that this study, despite its age, offered appropriate data to rely on.

For common industry processes like compost production and goods transport, we relied on EcoInvent, an industry-standard database that offers carbon impact values for common processes in the supply chain. 

When we considered the impacts of our packaging and final shipment to customers, we trusted the data provided by our packaging supplier, our fulfillment partners, and Pachama, whom we’ve chosen to work with on account of their commitment to sustainability.

PRODUCTION

The first step of the LCA was to measure the emissions that resulted from creating our Potting MIx.. To do this, we looked at the total emissions created during the production of each ingredient that makes up our potting mix.

Rosy’s Indoor Potting Mix is an 8 quart mixture of three ingredients: biochar, vegan plant-based compost, and mycorrhizal fungi. The varying weights and unique production process of each ingredient defines the carbon impact created during the production stage of the life cycle. 

Biochar

Biochar is our hero ingredient and helps us fulfill our mission: to offer customers a soil product that not only improves soil health and plant growth, but helps mitigate Climate Change through a production process that captures and stores high amounts of atmospheric carbon dioxide. That carbon-capturing process, commonly known as “carbon sequestration,” is responsible for biochar’s potential to divert billions of tons of carbon out of our atmosphere per year, according to experts.   

Biochar’s superpower is a result of converting what would otherwise be waste into a carbon-rich soil additive. All organic materials, like the wood waste we source from, are made from carbon. When left to decay over long periods of time, that carbon is slowly released into the air. We can prevent this by creating biochar instead of letting the organic waste go to a landfill and decay, locking the carbon inside and eliminating the potential for carbon emissions. So when we think about the net impact of producing biochar for our Potting Mix, it’s important to consider how much we avoided simply by producing biochar itself.  

Rosy's biochar is created through a process called pyrolysis. Wood scraps are heated to extremely high temperatures in an environment deprived of oxygen. Without oxygen, the wood scraps can’t ignite (that would send carbon into the atmosphere). Instead, those wood scraps remain in a solid form and keep all that carbon locked inside. Once biochar is created, it’s much harder for the organic carbon to decay because it is transformed into a porous, carbon-dense substance with a high surface area. This property happens to make it excellent at holding soil nutrients, filtering water, and encouraging strong plant growth. And, when we combine it with the other ingredients in our potting mix, it creates a superior product specifically designed to support plants.   

To calculate the precise net carbon impact of the biochar in our bag of Potting Mix, we referred to a 2009 Cornell study which accounted for both the energy demands of the pyrolysis process as well as the amount of carbon sequestered by converting wood into biochar. They found that for every ton of biochar produced, about 3 tons of carbon emissions were avoided.  

We applied those findings to our biochar production process and found that for every bag of Potting Mix we make, 2.72 kg of CO2 emissions are prevented from being emitted.   

Compost

Compost, when combined with our biochar, makes up the base of our potting mix. We’ve sourced compost from a local operation, where green and wood waste scraps are collected into large piles. As it composts, each pile becomes hot enough to break down those inputs into high-quality organic material. After it’s watered and stirred regularly over the course of months, the result is a nutrient-rich soil ingredient.  

Using the Ecoinvent database, we determined that producing the compost required for a single bag of our potting mix creates an emission of .16 kg of CO2.

Mycorrhizal Fungi

Although mycorrhizal fungi is a small fraction of our potting soil, their presence brings enormous benefits. It’s all due to the mutually beneficial relationship between these fungi and root systems. Plants entice mycorrhizal fungi to attach to their roots by releasing sugars. In return, the thread-like structures of these fungi increase the area, and consequently, the amount of nutrients and water available to the plant. With the help of these fungi, plants can reach far down into the soil for those typically hard-to-reach nutrients like phosphorus, calcium, and zinc. 

This ingredient is great from the standpoint of sustainable production as well. It’s produced by growing a plant, often some kind of grass, adding a spore of the fungus into the soil, and allowing fungi to grow using the plant as the medium. Therefore, manufacturing this ingredient is little more than the process used to grow plants. 

Or course there are carbon impacts incurred by farming, mainly due to the energy used by equipment and degradation of the soil. But given the relatively low mass of mycorrhizal fungi used in our potting mix, the production of this ingredient for one unit of our potting mix is quite low: .0002 kg CO2

PACKAGING

We source our packaging from a sustainability-focused packaging company, and have used their own LCA for this section. The packaging is a fully-recyclable, carbon-negative bag that mimics plastic, but is made from upcycled waste from regeneratively grown sugar cane. We ensure the impact created by our packaging is carbon negative by using this material, because it diverts more carbon from the atmosphere than it adds. 

According to our bag supplier’s calculations, the production of the bag used in a single Potting Mix unit carries a carbon negative impact of -.01 kg CO2 eq.    

TRANSPORT

The transport stage of the Potting Mix life cycle includes the emissions created when all three ingredients move from their source to the manufacturing site. In addition, the transport stage accounts for the carbon impact created when the Potting Mix is shipped to the end consumer.  

Biochar

Because the biochar is manufactured in the same site in the southeastern US that all three ingredients are ultimately mixed to create our potting soil, there is no transport impact for this component of the product.

Compost

The compost included in a bag of our Potting Mix is transported by truck from an industrial composting operation to our manufacturing site.

The carbon impact of this transport is .53 kg CO2 per bag produced.

Mycorrhizal Fungi

The fungus included in each bag has such a low mass that the transportation emissions are extremely low. though not completely negligible.

In total, the transport of our fungi ingredient from origin to our manufacturing site produces a carbon impact of .001 kg CO2 eq. 

Potting Mix to End Consumer

There is one more transport step to consider: the impact created by shipping our potting mix to our customers and retail shops all over the country. 

To keep our net carbon impact as low as possible, we’ve decided to partner with Pachama to offset the total emissions of these shipments. As opposed to traditional shipping, which doesn’t consider the emissions of plane, truck, and ocean ship transport, offset shipping allows us to pay an additional fee to ensure that Pachama purchases enough carbon offsets to keep our shipping emissions carbon neutral. We chose Pachama because we align closely with their mission and want to support other startups working to rebalance the carbon cycle.  

To put this into perspective, we measured what our emissions for shipment to a customer would be if shipped by truck 270 miles, the average distance a direct-to-consumer good must travel to the end customer. By opting for offset shipping, we saved .85 kg CO2.      

USE

Measuring the carbon impact of the use of our product was a challenge of our LCA as there is not much public data available for gardening activities. That said, we defined “use” as all that occurs after our customers add a bag of our Potting Mix to their soil. We’re confident this number is very low because our data sources for the production phase have already accounted for the possible emissions created when soil is added to the ground.

Our impact measurement for compost, based on the EcoInvent database, includes considerations of impact upon use. The same goes for our mycorrhizal fungi; our impact measurement for its carrier crop also takes into account possible emission during that growth process, which are understandably extremely low because plants work to sequester carbon as well. 

The same applies to our consideration of the possible impacts created when adding our biochar component to soil. The study we referred to for these calculations accounted for those emissions. 

With all that in mind, for the sake of measuring the Use portion of our total CO2 emission impact, we can consider it 0 kg. 

END OF LIFE

The final stage of the LCA is called the “End of Life.” This accounts for the potential carbon impact produced when packaging or the product itself is discarded as waste. For our Potting Mix, we’ll consider two variables. 

Discarded Packaging

As mentioned, our packaging is fully recyclable. By providing clear instructions about recycling our packaging online and on our label, we make it easy for our customers to recycle 100% of it. 

But even if customers do not recycle our packaging correctly, its particular plant-based ingredients ensure that, once in the landfill, it gradually decays into biogenic carbon instead of generating greenhouse gas emissions.

Our packaging supplier has accounted for both scenarios in their LCA , so the emissions in this stage are already covered in the above calculations.

Discarded Potting Mix

There are a few scenarios to consider that might lead a customer discarding some Potting Mix. 

For example, plants need to be re-potted as they grow.. We encourage our customers to reuse Potting Mix as much as possible by adding it to their new container. If a person does not want to reuse the soil, then we encourage them to compost it instead of throwing it away.

We’ve also considered the possibility of unused Potting Mix if somebody moves, leaving their garden, farm, or plants behind. In that scenario, we encourage our customers to compost the Potting Mix, give it to a friend, or put it into the ground to improve soil quality. 

If our customers choose to follow these considerations our Potting Mix yields zero additional carbon impact because the related emissions are accounted for in the production of the individual inputs.

RESULTS

When we take all of our supply chain steps into account, our carbon emissions can be calculated as follows: 

Production

-2.56 kg CO2

Packaging

-.01 kg CO2

Transportation

.53 kg CO2

Use 

0 kg CO2

End of Life

0 kg CO2

Total

-2.05 kg CO2

When the math is said and done, each bag of Rosy Potting Mix prevents over 2 kg of carbon from ending up in the atmosphere. To put that into perspective, let’s take a look at the carbon impact of creating a bag of traditional potting soil the same size as ours. 

COMPARED TO TRADITIONAL

A traditional bag of potting mix typically includes 70% peat moss, 10% perlite, 10% fertilizer, and 10% compost, all packaged in a polyethylene plastic bag. 

We can’t reasonably presume many of the data points required to complete an entire LCA of a traditional, non-biochar containing alternative. (We hope other soil companies will be encourage to produce their own LCA!) That said, by simply looking at the carbon impact of production alone demonstrates how minimal Rosy’s carbon impact is in comparison.

When we consider a bag of traditional potting mix of the same weight, and measure the impact of producing each of the above ingredients using the EcoInvent database, we see a carbon impact of +3.38 kg CO2. That’s almost triple that of our carbon footprint of -2.05 kg CO2.

These numbers are a calculation of one bag of potting mix. But it's useful to consider the process on a larger scale.  

Many potting mixes are made with a large majority of peat moss. Although peat moss is a good growth medium, its harvest releases high quantities of carbon into the atmosphere. According to the International Union for Conservation of Nature, although harvested peatlands only account for .3% of land surface, they are responsible for the release of 1.9 gigatonnes of CO2eq annually, or 5% of the total CO2 released globally. 

By opting for biochar, we support an industry that has the potential to sequester ​​2.2-4.4 gigatons of CO2 per year by 2050. 

CONCLUSION

It’s important to remember that this evaluation is the first step in a process of improvement that never ends. As we grow and learn more about carbon impacts and how to better measure them, we’ll improve the precision of our understanding within our supply chain. And with greater certainty we’ll be able to make the right changes to reduce our footprint even more. 

And for that, we need your help. We want to hear from our customers who may have questions or concerns. We hope to continue to meet with experts who are well-versed in sustainability. What are we doing right? Where are we missing? Let us know how we’re doing so we can collaborate and continue to improve on our mission. We couldn’t do it without you!


Earth Positive Indoor Potting Mix

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We craft our mixes with the specific needs of houseplants in mind. Every blend contains all-natural, sustainable ingredients that optimize drainage, deliver plant-boosting nutrients and support a diverse community of beneficial fungi and microbes. It’s living soil in a bag — the perfect way to give your plants the TLC they need to thrive.
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