Agroecology from A to Z

Adventures in Agroecology and Food Systems


Vermicompost at Jenner Farm – Guest Blogger Eleanore Nelson

Congratulations to Eleanore Nelson, whose senior project was picked for the Environmental Studies baccalaureate presentation at Prescott College. Here’s Eleanore’s description of her project. It was a pleasure to be your mentor Eleanore!

-Allison Jack


In current industrial large-scale agriculture, the “cycle” of the nutrient cycle is completely fractured. Currently, food is grown in soil, harvested, processed, packaged, and consumed by people or animals maybe in another state or country. The excrement that comes out of both humans and animals are jammed packed with vital nutrients that are actually limiting to a plant’s growth. Sadly, this fecal matter isn’t returned to the soil from which the fresh food was originally grown. It is flushed down the toilet to be treated or in the case of animal manure, kept in large man-made lakes, where anaerobic decomposition takes over and methane gas (CH4) is emitted. Livestock enteric (intestinal) fermentation and manure management in 2010 accounted for 21.2% and 7.8% of the total CH4 emissions in the US respectively (US EPA 2012).

Prescott College is in the process of developing animal traction for our school’s farm, located in Skull Valley, AZ. The addition of draft animals will create independence from the fossil fuels that power our tractor. However, with the independence from fossil fuels requires additional planning: developing a perennial pasture, building a structure for the draft animals to live under during the cold winter months (yes it does get cold in Arizona!), and properly recycling their manure.

For my senior project I designed and constructed a pilot scale model of a vermicomposting system that could be used to properly compost horse manure to yield a very valuable product for crop production.

So why vermicompost and not just regular compost?

By feeding animal manures, food scraps and other organic matter to worms, you are making the compost product richer than just thermophilic compost (compost that has experienced temperatures over 149F). First of all there is a very diverse soil microbe community present in the vermicompost. When the worms consume organic matter, their guts cover their castings (the technical term for worm poop) with a mucous that attracts other soil organisms like mites or nematodes, which in turn attract others. Soon enough, the vermicompost is teeming with a diverse collective of decomposers. Additionally, studies have shown that there is an increase in plant available nutrients in vermicompost compared to compost, that vermicompost suppresses plant pathogens in the soil, and, when used to recycle animal manures, a decrease in methane emissions.

Here’s my in-ground design that I like to call the “Vermi-pit”:

VC design schematic

The vermi-pit is lined with concrete blocks. There is an insulated cover that goes on top of the system to help keep the vermicompost cool in the summer and warm in the winter. Additionally, there is a screen that divides the system.

Here’s myself (and along with other students) building it:

First, Matt helped me use the tractor to dig a pit into the ground.


Then we lined the bottom of the pit with concrete blocks in order to keep the gophers out of the vermi-pit. There’s about a 10 inch space in the middle where the 4’x 1’8’’ screen is placed where we laid down chicken wire to enforce gopher protection. We then lined the walls of the pit with concrete blocks (4’’ x 16’’ x 8’’) only two high, three for the width and four for the length, totaling 28 blocks. The screen was placed in the middle.



Then we backfilled in the space between the wall of the pit and the concrete blocks with soil.


Facing West Cottonwood Lane, the left side of the pit is about 14 ft3 (0.4 m3) and the right side is about 12 ft3 (0.34 m3).

I cut an insolated door in half, each piece acting as a cover for each side of the system.


Final Result

veri-pit w lid

How it works:

The idea behind this design is the ability to conduct thermophilic composting on one side of the system, while the other side is being fed to worms. The thermophilic composting side will act as the battery to keep the vermicompost on the other side insulated and warm. Once the worms are done consuming the horse manure and food scraps on one side, they will migrate through the screen to compost that had just been under thermophilic conditions. Then one can harvest vermicompost without having to pick out worms for hours on end. This is called passive harvesting. Once the vermicompost is collected out of the pit, then horse manure, food scraps and agricultural residues can thrown into the pit to go under thermophilic composting, again acting as the battery to keep the other side, which is now being eaten by worms, warm and insulated.

Vermi-pit schematic

The materials were all very relatively cheap. The most expensive purchase was for the worms. I acquired 10 lbs of worms, 5 lbs from a seller who fed his worms horse manure, and 5 lbs from a seller who fed her worms cow manure. I began by inoculating about 14-ft3 of aged horse manure with about 5-lbs of worms. I didn’t want to put all of my worms in there just incase something were to happen and all of them died, I was on a tight budget!

The insulated door that I placed on top of the system helped keep the vermicompost temperature at around 68 F, which is ideal for worms. Without the insulated cover and no worms, the temperature of the pile was ~50 F. Worms are very susceptible to cold and hot temperatures, and in Arizona we have both. During the summer in Skull Valley, the temperatures can reach above 100 F, and during the winter the temperatures can go below freezing. The door also helps in decreasing the rate of evapo-transpiration. Worms like very moist conditions (80-90% moisture content), which can be a roadblock in raising worms in such an arid climate. In the summer I plan on having a shade cloth over the entire system and removing the door so it doesn’t get too hot in the compost pile, and it has shade to prevent extreme water loss.

Although the climate in Skull Valley is very arid and can be both very hot and cold, the vermicompost is completely insulated in the ground. I observed temperatures between 66-68F for four weeks after inoculation. However, the right side, which I filled with field culls never reached a thermophilic compositing stage. So the battery idea may not be feasible. However, I did find mating worms and cocoons in the vermicompost, indicating that the temperature and moisture content are ideal. So worms can thrive in Arizona and do their work as master decomposers to add value to an already rich, all natural product. Additionally, since the worms are reproducing, the farm managers could harvest the excess worms and utilize them as a source of protein for their flock of chickens. Everyone wins when you reconnect the cycle!

What once was horse manure pellets, now looks like soil…

finished material - hands

A pair of mating worms

worms mating - hands

A cocoon

cocoon - hands



Card, A.B., Anderson, J.V., & Davis, J.G. 2004. 1.224, Vermicomposting Horse Manure. Colorado State University Cooperative Extension. Retrieved from

US EPA. 2012. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010. Retrieved from Viewed November 2012.

Ussery, H. 2008, April. Poultry feed from worm bins. Backyard Poultry Magazine, 3(2), Retrieved from Vermicomposting.html


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Tepary bean harvest at Jenner Farm

It’s impossible not to notice the change of seasons at a farm. Once that first frost happens, there is no turning back the clock. We’ve had a few great work parties out at the farm in the last three weeks. Students are working on green building projects, final harvesting, threshing, winnowing and even some seed saving.

We harvested 25 pounds of tepary beans from a student research plot from the summer agroecology course. The students were investigating the drought tolerance of different heritage tepary bean varieties from Native Seeds/SEARCH in Tucson. We got to them a little late in the season, so there were at least 10 pounds on the ground and Rabbit Run Farm had harvested 10 pounds earlier in the season. I wonder if 45 pounds of dry beans is a good yield for the plot size? I left students to their own devices on figuring out the threshing and winnowing. They really got an efficient system going. A few students harvested the bean plants, a few more stomped on the plants on a tarp to release the seeds and a few more used the wind to separate the chaff from the beans. It was so much fun I almost hate to buy a small combine for the tractor! I’m aiming to add this piece of equipment so that students can expand our tepary bean production and potentially provide dry beans for the campus food system.

I told the students that I was impressed that they developed a workable threshing and winnowing system so quickly. I said “it’s almost like you’re all intuitive threshers and winnowers.” Then a student answered, “After 10,000 years of agriculture, shouldn’t we all be intuitive threshers and winnowers?” Well said!

Winnowing tepary beans with the wind (and foot stomping threshing on a tarp in the background)

17 varieties of tepary bean Phaseolus acutifolius (mixed with some common beans Phaseolus vulgaris) ready for phase II winnowing

Earlier in the season during the agroecology summer course, Dr. Jean Stutz from ASU visited and did a lesson on Arbuscular Mycorrhizal Fungi (AMF). AMF are known to help increase drought tolerance in their plant hosts. She taught the students how to take root samples for AMF analysis and showed us microscopy images of stained roots back in the classroom. Jean has Prescott ties so I’m really looking forward to collaborating with her in the future, especially since I am a fellow rhizosphere microbial ecologist!

Dr. Jean Stutz demonstrates how to take root samples to test for AMF colonization

Root sampling

Plants in rows farthest from the camera received full irrigation while those in the rows closest to the camera were purposefully drought stressed to see how they responded

One of Dr. Jean Stutz’ microscopy images of AMF colonized root tissue

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Dung fungi and earthworms, oh my!

Moving to the desert from the soggy Northeast (via the soggy Northwest), I had a horrible feeling that I would never see a mushroom growing out of the ground or a wild earthworm again. It turns out I was wrong! Especially during a heavy monsoon season.

I TAed the Cornell Plant Pathology and Plant-Microbe Biology course “Magical Molds Mischievous Mushrooms” in 2011 and we had a fun unit on dung fungi. Based on the amazing dung fungi I saw at Jenner Farm last week, I’m really looking forward to developing a soil microbiology course in the future that includes these fascinating organisms and their role in decomposition and soil nutrient cycling.

Just a note, I really can’t mention mushrooms without pointing everyone to my friend and mentor, Kathie Hodge’s, Mushroom Blog.

Dung fungi in horse manure
More dung fungi on horse manure
Coprinus spp. or “Inky cap”

And now, on to the earthworm casts. The earthworms at Jenner Farm are really loving the monsoon season. They have been surfacing and doing some serious construction and remodeling on their burrows.

I had always seen earthworm casts in my mom’s garden, but I didn’t get interested in them scientifically until I read Darwin’s classic “The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits” in 2000. Check out this etching from the original publication (courtesy of the American Philosophical Society’s museum in Philadelphia).


Earthworm casts at the entrance of a burrow

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Rabbit Run Farm at the Prescott Farmer’s Market

Matt Hyde and Sarah Wertz of Rabbit Run Farms

Congrats to Matt and Sarah of Rabbit Run Farm for this great August cover photo in Mountain Living magazine!

Matt and Sarah farm commercially at Prescott College’s Jenner Farm as part of a land sharing agreement. In addition to running their business, they manage the campus farm and take care of our research plots throughout the summer agroecology course.

I had the pleasure of helping out at the Rabbit Run stand at the Prescott Farmer’s Market earlier in the summer. It’s a lovely outdoor market with a nice variety of vegetables, grains/pastas, preserved foods and prepared food. The steady stream of customers were definitely fresh food enthusiasts and it was fun to hear their cooking plans for different crops. One couple even brought some canned bread and butter pickles as a gift for their favorite farmers! They made the pickles from cucumbers they had bought at the stand the week before. Now that’s farmer appreciation!

The market in full swing

Armenian cucumbers


Eleanore, a student in the summer agroecology course, spent the day helping out at market too.

I’m considering having students work a stand at the market at least once during the summer course as a way to gain a deeper understanding of the economics of small-scale farming. Rebekah Doyle had the students carry out rapid farmer’s market assessments this summer and I learned a lot from their final reports and presentations.

The first box from the Prescott College CSA share, grown by Rabbit Run Farm

My husband and I are enjoying the Prescott College CSA, managed by Erin Lingo. Each week is just the right amount to last us until the next pick up. The perfect option when you can’t garden for yourself. I’m in food heaven in the desert!

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Buen Viaje to Tim Crews!

Well, it’s official. Tim gave me the key to the mesquite hammer mill trailer on Saturday and he and Sarah headed out for Kansas yesterday. Safe travels and agroecological adventures to you both!

Read the full article with comments.


Sarah and Tim Crews and their dog, Trucha, spend a snowy day in the Prescott National Forest a year ago. Tim is leaving his job of 18 years as director of the agroecology program at Prescott College.

9/3/2012 9:47:00 PM
Long-time Prescott College professor pulls up stakes

Ken Hedler
The Daily Courier

PRESCOTT – Tim Crews arrived at Prescott College 18 years ago to start the agroecology program, and left Monday to become research director at the Land Institute in Salina, Kan.

Defining agroecology, Crews said, “It is looking at farms as ecosystems with insects and nutrient cycling, trying to manage them more as ecosystems than factories.”

Crews, who earned a doctorate in ecology and evolutionary biology at Cornell University in Ithaca, N.Y., recalled that Prescott College appealed to him by offering a commitment to “field-based studies, bridging with rigorous academics.”

Besides establishing an off-campus farm, Crews helped to found the Prescott Farmers Market in 1997 and the community supported agriculture (farm co-op) program on campus three years later.

Crews, 51, regards launching the agroecology program as his biggest accomplishment because it has gained a national reputation for the small private college. The program now offers master’s degrees.

Crews said he has become acquainted over the years with the Land Institute, a nonprofit organization and research center housed on the banks of the Smoky Hill River.

The institute’s website states, “We are creating a new agriculture informed by nature. It produces food while preserving biodiversity. It minimizes the inevitable damage associated with annual crops: soil loss and degradation, water fouled with toxins and drained of its oxygen, and high greenhouse gas emissions.”

That mission meshes with Crews’ values.

“I have been collaborating with them for about 12 years, and I believe very strongly in their goal of developing farming systems that function much more like the native ecosystems they replaced,” Crews said.

The institute’s managing director, Scott Seirer, said, “We have known him for several years. He’s an ecologist, and we have to add that role to our science mix. … He will also be research director, so he will supervise the science staff.”

Scientists at the institute conduct research to find perennial grain crops.

“Tim’s role as an ecologist will help us look at the concept of growing more than one crop in the field at the same time,” Seirer said.

While looking forward to his new challenge, Crews said he and his wife of 23 years, Sarah, will miss Prescott and walking their dog, Trucha, in the Prescott National Forest.

Sarah Crews works in the hospice field.

She and Tim have two daughters: Ruby, 21, and Claire, 18, who attend Hamline University in St. Paul, Minn., and Hampshire College in Amherst, Mass., respectively.

Crews’ former students will miss him as well.

“I would definitely say he was my favorite professor,” said Shanti Rade, a 2001 graduate who operates a small farm with husband Cory in Paulden. “He was an inspiring teacher. He is just a dynamic teacher. He really got his students excited about the subject matter.”

Crews said Prescott College hired an “excellent replacement,” Allison Jack, who earned a doctorate at Cornell from the Department of Plant Pathology & Plant-Microbe Biology.

Referring to his former employer, Crews said, “It’s a gem. I’ll miss it.”

p.s. I just found this photo of Tim and I at Tim and Sarah’s farewell party.

The passing of the agroecological torch

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Pickling adventures continued

I bought some pickling cucumbers at the Prescott Farmers Market earlier this summer. When I mentioned to Matt, one  of Jenner Farm’s managers also farming commercially as Rabbit Run Farms, that I had started a small crock of pickles he got a strange look in his eye.

He said, “I have 150 pounds of harvested pickling cucumbers, no cold storage and a 55 gallon food grade drum.”

I said, “It’s on!”

Eleanore, a brave agroecology student, volunteered her house for a pickling party. Eleanore and I processed all of the cucumbers and got the crock fermenting in her living room. She says she can hear the bubbles rising at night when it’s quiet. It’s been almost 4 weeks, so these pickles are close to ready for de-brining and additional processing. I can’t wait!

Me cleaning and prepping the fermentation vessel

That’s a lot of cucumbers

More grape leaves from the Prescott College edible campus gardens

Still a lot of cucumbers, soon to be a lot of pickles!

Turkey roasting bags filled with brine as a seal

Eleanore was very brave to have this fermentation vessel in her living room!

A note to anyone attempting large batches:

We had really bad luck with the 3 gallon turkey roasting bags that the USDA recommends to use for a seal for the long brine process. They kept leaking! Luckily we filled them with brine, so when they leaked, they did not disturb the salt content of the pickling brine. While troubleshooting, Eleanore and I removed 16 gallons of brine and replaced the turkey roasting bags with 2.5 gallon freezer storage bags and have had no additional problems with the seal. The brine we pulled off during troubleshooting smelled so delicious, like deli pickle juice, that I wanted to drink it. So I think this batch will turn out well. We’ll see soon enough.

Update: The pickles turned out great, and we sold a bunch of them as a fundraiser to support Sandor Katz’s visit to Prescott College for Food Day 2012.

I admit I'm looking a bit like a mad scientist here, but after waiting 5 weeks to see if we had pickles or a huge slimy mess that we would have to compost, I was pretty darn excited that it worked!

I admit I’m looking a bit like a mad scientist here, but after waiting 5 weeks to see if we had pickles or a huge slimy mess that we would have to compost, I was pretty darn excited that it worked!

Lactic acid fermented cucumbers after 5 weeks of fermentation

Lactic acid fermented cucumbers after 5 weeks of fermentation

Pickles waiting to be sold in delicious brine

Pickles waiting to be sold in delicious brine, they were so crunchy you could hear it when someone next to you was eating one!

Eleanore and Nicole selling pickles at Rabbit Run Farm's booth at market

Eleanore and Nicole selling pickles at Rabbit Run Farm’s booth at market

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Entomology at Jenner Farm

Earlier this summer in the agroecology course held at Prescott College’s Jenner Farm, a 20 acre teaching and research farm in Skull Valley, AZ, we had a visit from Dr. Neil Cobb, an entomologist from Northern Arizona University.

A beautiful day to study entomology at Jenner Farm

Neil Cobb shows Prescott College agroecology students members of many of the insect orders

Blister Beetles mating!