ICAW 2022: Why is Soil Biodiversity Important?

Our final post to round out International Compost Awareness Week will tie back to this year’s theme, “Recipe for Regeneration.

So how does compost make our food more nutritious, the air we breathe cleaner, and our climate healthier?

In short, by supporting soil biodiversity through the contribution of organic matter in the form of nutrients and microorganisms (i.e. bacteria and fungi) which are the foundation of a healthy soil food web. Learn more about soil biodiversity’s role in agriculture, climate change, the environment, and human health:

Soil biodiversity and agriculture

Plant Nutrition: Soil microorganisms are both a source and a catalyst for supplying nutrients for plant growth. They make nutrients available to plants through interactions with other soil organisms and abiotic factors such as temperature, pH, moisture content. Nutrients derived from organic matter can reduce the reliance and misuse of synthetic inputs.

Soil biodiversity and climate change

Carbon Sequestration: Soils can either release or store carbon. Healthy soils store more carbon than that stored in the atmosphere and vegetation combined. In addition to applying compost, soil management practices that allow soils to be carbon sinks rather sources include: reduced or no soil tillage/disruption, limiting overgrazing and overapplication of fertilizers and pesticides, keeping the ground covered with cover crops and a diversity of plants.

Soil biodiversity and environmental protection

Ecosystem Services: Soil biodiversity also prevents erosion and bioremediates contaminated soils of heavy metals and toxins

Soil biodiversity and human health

Disease Regulation: Many drugs and vaccines stem from soil organisms (e.g. penicillin), antioxidants from healthy plants stimulate our immune system and contribute to hormone regulation, and studies provide evidence that exposure to soil microorganisms can prevent chronic inflammatory diseases.

Food Production: Soil bacteria and fungi are traditionally used in the production of soy sauce, cheese, wine, and other fermented food and beverages.

Source and to learn more: “The State of Knowledge of Soil Biodiversity: Summary for Policymakers”

ICAW 2022: Composting in the Forbes Garden

Welcome back everyone for another day of celebrating compost!

Today we feature our efforts to restart composting in the campus garden at Forbes College after a hiatus due to the pandemic.

We realized we needed better oversight of the composting efforts in this space to minimize odors, so we hired a student, Jesus Arroyo ’24, to coordinate food scraps drop-offs and to manage the compost pile and tumblers.

Check out our progress so far:

Day 1: Jesus using a pitch fork to pick-up food scraps delivered from a nearby student food co-op
Day 1: Layering the food scraps into our composting pile enclosed by a wire cage. We put a thick layer of wood chips at the base for leachate control
We also pre-mix the food scraps into the wood chips for even distribution. Here we used a ratio of about 2 parts wood to 1 part food. For higher moisture food like shown above, we’ll use a higher ratio of 3:1
Finished pile after Day 1
A few days later – using a temperature probe to monitor compost activity. We’ve managed temperatures in the “steady” (80 – 100 F) to “active” (101 – 130) ranges, but we need to increase our pile size to at least 4ft by 4ft by 4ft to get to the “hot” range (131 – 160 F)
Day 6 after more feedstocks have been added
First Turn: After 3.5 weeks when the temperatures stopped climbing, Jesus mixed the pile to allow microbes to access fresher material and to ensure proper aeration as the pile compacted. The goal will be to get the entire pile to look like the dark brown color in the center
Tumblers! The garden also has several of these to provide extra capacity, however, they can only handle so much. Still, they are a user-friendly option that is great for the new composter

Stay tuned for a video to meet Jesus and to see the work in action!

Thanks for reading!

Check back in for one more post tomorrow!

ICAW 2022: Composting at Home with Ted Borer

Happy 4th day of International Compost Awareness Week!

Today’s post we are pleased to share a Q&A about home composting with Ted Borer.

By day, Ted is an engineer who serves as Princeton University’s Energy Plant Director. He oversees day to day operations and long-term planning to achieve a carbon-neutral campus. Ted is equally as passionate about sustainability in his personal life. He bicycles to work 12 months a year and follows a plant-based diet. His home includes everything from shower drain heat recovery to a chicken coop and an area for composting!

Read more about Ted’s composting journey and process, as well as his advice for new backyard composters below:

Ted Borer pictured with his 3-bin composting set-up.
  1. When did you start composting and why?

My wife and I started composting in 1989. Compost bins were one of the first things I built when we bought our first house. There were a lot of trees and shrubs and we both enjoy gardening. We wanted to manage our yard waste and food scraps and re-incorporate them into the gardens.

  1. What do you compost?

Yard waste and non-meat, non-fat food scraps: Sticks, branches, leaves, garden weeds, bark from firewood, sawdust, sometimes grass clippings, poultry and rabbit bedding/waste, food scraps with no meat or dairy.

Ted using a chipper-shredder machine to grind up large pieces of wood into smaller pieces to reduce material size to enable hot composting
  1. What benefits have you’ve seen as a result of composting or applying compost?

First is joy! It’s really fun to see the temperature rise and fall as I change the carbon/nitrogen (brown/green) balance or mix up the piles, or run things through a chipper/shredder to break them down and aerate them, or add water. It’s a fascinating process to observe. It’s part of an endless cycle of life-death-decay-renewal.

Second, it reduces the amount of waste that leaves our property. Ideally, I’d like nothing organic to leave our property. We have a ways to go before achieving that goal. But we certainly don’t get rid of any yard waste and essentially zero food scraps. It’s too valuable.

Third, like much of this area, our yard has very little topsoil and is mostly clay and shale. By mixing in finished compost, I can lighten any soil and plants will grow better in it. Lighter soil absorbs more water instead of letting rain sheet-flow into a creek; taking nutrients downstream with it. When I top-dress or mulch shrubs with compost, they grow faster and are more healthy.

Ted’s active compost pile. Ted uses a temperature probe to ensure hot composting (i.e. when temps are between 131 – 160 F, the range needed for at least 3 days to kill off pathogens)
  1. What advice do you have to anyone looking to start composting at home?

You don’t have to do everything all at once. Starting composting can be done with little time and effort – but it grows over time as you learn more! Maybe start with kitchen scraps and leaves and a small “compost tumbler”. But, be aware that composting works better and is more stable the larger you go. I built a three-compost-bin system and use a pretty large chipper-shredder to manage all our yard waste and animal bedding. The bins are 48” x 48” x 48”. I cycle from bin-to-bin as the compost breaks down.

If you do want to start on a small scale, learn about vermiculture! A tiny pile of kitchen scraps in the back yard is not a “composting system”. It will just attract animals.

Get a book like: Let It Rot!: The Gardener’s Guide to Composting (Third Edition) (Storey’s Down-To-Earth Guides): Campbell, Stu: 9781580170239: Books: Amazon.com

Thanks for reading!

Stay tuned for another post on backyard composting tomorrow, featuring the Forbes Garden!

ICAW 2022: Facility Updates

Happy International Compost Awareness Week!

Our first celebratory post is an update on the status of the composting facility.

The facility has passed all inspections – building, electric, plumbing – and we are currently working on preparing SCRAPPY and the facility to restart operations.

Check out the improvements we have made to the composting system based on lessons learned from our first 1.5 years of operation:

Screener Upgrades:

To prevent the build-up of compost inside of the off-loading screener and to improve the rate at which compost is off-loaded from the composting system, we’ve installed a screener with more openings and with larger access doors

Old screener with the end panel having smaller access doors and no openings
New screener with larger access doors and mesh wire openings on the end panel

HOPPER Upgrade:

Because we process bulkier and solid items (e.g. large watermelon rinds), we have installed a wider and stronger agitator mechanism to facilitate the movement of food to the shredder below.

Old agitator with two narrow flaps
New agitator with one, but wider and more durable flap that covers the entire width of the hopper

Thanks for reading!

Stay tuned for the next two posts on solutions for home composting!

ICAW 2022 Preview: Recipe for Regeneration

Next week, May 1 – 7, is International Compost Awareness Week (ICAW)!

Just as a chef pulls together the best ingredients to create the perfect recipe, the 2022 theme, Recipe for Regeneration: Compost, focuses on the crucial role recycling our food scraps and yard trimmings plays by creating compost, which when added to soil results in a recipe that makes our food more nutritious, the air we breathe cleaner, and our climate healthier overall.

With Earth Month just wrapping up and in honor of ICAW, the ComPOSTer will post several times during the week. Stay tuned for the following content:

  • SCRAPPY Updates
  • Composting in the Forbes Garden
  • Composting at Home Q&A with Ted Borer
  • Why is Soil Biodiversity Important?

Lights, Camera, Action (soon)!

A quick update to say that we officially have power at our new location!

Successful energization of the composting facility – lights, exhaust vent, heaters, and composting system
A view of the back of the facility and wood shed
Wood shed
Inside of wood shed which also has lighting

Big Goals for 2022!

Dear friends of the S.C.R.A.P. Lab,

We hope all forty-two of you are continuing to stay healthy and are enjoying a great start to 2022 ! As with every first post of a new year and new semester, the ComPOSTer takes a moment to recap the past year and more importantly, provide some optimism about what is to come in the year ahead.

Our year started off on a high note, beginning with a tour of the new facility to a group of graduate students and staff during Princeton’s Wintersession. Pictured above: Gina Talt ’15 explaining the University’s wasted food diversion program


Unfortunately our original plan to relocate and re-open the S.C.R.A.P. Lab during the spring of 2021 was halted due to permitting challenges. While the relocation was delayed to early September, progress was swift, and the entire facility and composting system were reassembled in November. In the meantime, the ComPOSTer completed its faculty Q&A blog series with the graduation of Wesley Wiggins ’21 and covered other news about legislative updates on the state of organics recycling in New Jersey, and world news such as The Global Methane Pledge.

Additionally, we have made good use of the pause in operations by getting more involved in community partnerships in food and agriculture research, understanding how environmental justice factors into these issues, deepening our operations training, networking with other system operators and industry experts, and developing a re-start plan that includes practical tweaks to the facility and equipment that will help make operations easier. 

More new site progress! The exterior design and construction is now complete with the Shelter Cover shed on the right and concrete pad connecting it to the main facility

2022 PLANS

The last remaining  step before we can restart operations is the electrical hookup. We are hopeful students will once again have a hand in operations this semester. Then we are planning to pick-up where we started on our operational and research efforts, including:

  • Making improvements to our composting equipment to better meet our needs
  • On-boarding an assistant operational manager
  • Continuing to test and expand compostable serviceware options in the Frist Gallery
  • Integration of research efforts with operational testing of different feedstocks and recipes (i.e. to what extent can we substitute our purchased wood shavings for wood chips, leaves, or even compostable serviceware, the latter of which looks like it could be here to stay? What is the impact on emissions, microbial communities, nutrient density, etc.)?
  • Testing of new food scraps collection and drop-off systems to expand reach across campus. Now with our own van!
  • Launching new graphics and informational signage for the relocated facility
  • Using Tableau Public to better visualize and communicate our composting data
  • Continuing to raise awareness about the environmental justice implications of composting
  • Seeking new avenues of academic engagement (currently helping to plan a first-year seminar course)

Stay tuned for a notice about a re-launch ceremony when composting officially begins, similar to our ribbon-cutting event in 2018

New facility photos and Congress briefing on “forever chemicals”

Progress at 300 Washington Rd.

New updates include the installation of an exhaust fan (back of the facility) and the pouring of the concrete pad for the adjacent wood shed

Concrete pad for the foundation of the wood shed that will store the carbon feedstocks for composting operations. A smaller “hoop” structure will cover the footprint

Jaffé briefs Congress on “forever chemicals”

Peter Jaffé
William L. Knapp ’47 Professor of Civil Engineering
Professor of Civil and Environmental Engineering

Meanwhile… Testifying before Congress, Professor Peter Jaffé called on the federal government to support research into and mitigation of chemicals called PFAS, or “forever chemicals” because of the time they take to break down in the environment. Earlier this year, the ComPOSTer interviewed Dr. Jaffé about his research to mitigate PFAS contamination and to remove the chemical from groundwater and the environment. Dr. Jaffé recommended that Congress direct more funding into research on the forever chemicals, arguing that a better understanding of their impacts will help with mitigation.

Read more about Dr. Jaffe’s testimony and find the full briefing here: https://engineering.princeton.edu/news/2021/12/09/jaffe-briefs-congress-forever-chemicals

In Context: PFAS & Compost

In a recent BioCycle column, Dr. Sally Brown shows how the biggest risk of exposure to PFAS comes from direct exposure pathways to dust, cosmetics, cookware and packaging (including the food that touches both). As a result, PFAS ends up inn compost but concentrations are much lower than those in many household products. Dr. Brown argues that the manufacturing of products with PFAS should be restricted to prevent the direct exposure to these chemicals, instead of restrictions being placed on down-stream sources of PFAS like compost. The compostable food packaging industry is currently testing and developing viable alternatives that don’t include PFAS so these chemicals don’t end up in composts in the first place. However they are currently not widely available or in limited supply.

2-yr old compost, new design features and other reconstruction updates!

This month we’ve made significant progress on the reconstruction of the composting facility. Check out the photo essay below to see and hear about several new and exciting design and infrastructure improvements (and some well-aged compost)!

Pictured above: The new site on a crisp fall morning.
Foreground: On-going landscape grading work
Background: The outline and beginning construction of a covered storage space for our carbon source, and behind that the electric equipment for the facility
The composting system was completely reassembled last week. The digestion vessel and loading hopper are now stationed on top of elevated slabs which will allow our receiving receptacle trailer to fit completely under the screener on the off-loading end. Next up: Cleaning all the debris and dust accumulated in almost 2 years of storage
Nearly 2-year old compost!
This compost “brick” was found inside of the composting system . Because of the emergency shutdown during spring 2020, some of the food scraps and wood shavings remained, and they ended up naturally decomposing

More updates to come in December. We are getting closer to a “power on” date and hope to resume composting operations in January of the New Year.

Have a happy and healthy Thanksgiving holiday!

Relocation Update, Webinar & More

In this ComPOSTer, we provide an update on our facility relocation and highlight an interesting upcoming webinar on Wasted Food Solutions and more composting-related current events.

SCRAPPY on the move

Efforts are underway to move the composting system into the reconstructed facility. Pictured above is a forklift transporting “SCRAPPY” from its storage location to the facility where it will be placed on the elevated slab below

Wasted Food Solutions Webinar

Join this virtual workshop co-hosted by the Center for EcoTechnology (CET) and New Jersey Composting Council (NJCC) to learn about strategies for implementing wasted food prevention, donation, and diversion programs in businesses in the food service sector. Although specific to New Jersey and its Food Waste Law, participants will leave with an understanding of the next steps for building wasted food management into their operations and gain access to digital resources and guidance documents. All attendees will also have access to free one-on-one support from CET, which will take place in the last hour of the workshop.


In the News

The Global Methane Pledge was introduced recently as an ambitious plan to slash global methane emissions 30 percent by 2030.

The pledge is a big step for limiting the potent greenhouse gas, but critics are quick to point out that the pledge fails to address limiting emissions from the largest source of methane globally — agriculture.

  • The pledge only promises to incentivize “the deployment of improved manure management systems, anaerobic digesters, new livestock feeds, composting, and other practices.”
  • In the U.S., the Biden administration plans to pose direct restrictions on the oil and gas industry, but only voluntary adoption measures with the agriculture sector.
  • Meanwhile, environmental justice groups believe the solution lies in transitioning away from the large-scale livestock operations that are one of the biggest contributors of methane emissions. These facilities dump manure into large “lagoons” which creates unsafe air and groundwater in the disproportionately Black, Latino, Indigenous, and white rural surrounding communities.

As an alternative solution, New Jersey Senator Cory Booker reintroduced the Farm System Reform Act, which imposes a moratorium on these industrial facilities and creates federal financial assistance for farmers to transition to pasture-based dairy and hog farming. 

Read more: There’s a major gap in the new methane pledge: Agriculture

NOTE: If managed properly, grass-fed animal operations can be a more sustainable option and healthier to nearby communities, however the scientific community is still in debate over whether pasture-raised systems (in particular beef), are consistently more climate-friendly than industrial beef.