Cardboard layering deep compost mulch for weed suppression, soil health, and profitability

Final report for FW22-393

Project Type: Farmer/Rancher
Funds awarded in 2022: $24,920.00
Projected End Date: 10/01/2023
Host Institution Award ID: G344-22-W8613
Grant Recipient: Sweet Hollow Farm
Region: Western
State: Idaho
Principal Investigator:
Jonah Sloven
Sweet Hollow Farm
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Project Information


Weed pressure is a particular issue at Sweet Hollow Farm. Perennial bindweed is abundant across the farm due to its ability to spread by seed and through its vigorous rhizomes. In previous seasons, weed management consisted of spring-time tillage followed by intensive weeding throughout the growing season. Alongside the prohibitive time demand of this approach, the producers understand the harmful effects of continuous tillage to soil health and desire an alternative bindweed management strategy. Based on preliminary attempts at our farm and at a partnering farm, Foraging Farms, a cardboard layer deep compost mulch system (CLDCM) has shown potential against perennial bindweed. Qualitative assessment of the soil beneath the cardboard layer in these beds also shows worm activity, aggregate formation and moisture retention - indicators for healthy soil. Through this grant and in partnership with the University of Wyoming, we wish to answer the following research question: Can a cardboard layering and deep compost system (CLDCM) be used to reduce bindweed pressure while encouraging productive soil health and crop yield?  If successful, the CLDCM method will have significance for small-scale producers by showing that aggressive weed pressure can be managed without tillage while simultaneously building up soil health and farm profitability. *Bindweed photo in additional documents.

Results of the study will be shared with local and regional agricultural stakeholders through on-farm workshops, field days, and demonstrations. 

Project Objectives:

The project objectives include: 

  1. Weed suppression: Identify whether there is a quantifiable difference in bindweed presence in the cardboard layering and deep compost mulch (CLDCM) strategy compared to our current weed management system that relies on tillage and frequent manual weeding. Reducing weed pressure lessens labor hours for the farm, lowering costs and improving the quality of life for the farmers. Lower costs in turn increases profits for the farm. 
  2. Improving Soil Health: Soil samples will be collected at the beginning and end of the study period in the test and control produce beds. The soil samples will be analyzed for chemical, physical, and biological soil health indicators at the University of Wyoming. Comparing results will show if soil health is improving in the cardboard layering and deep compost system compared to our standard tilling practice. Soil health results from Sweet Hollow Farm will also be compared with soil samples from partnering farm, Foraging Farm, which has used the same CLDCM methods since it began five years ago. 
  3. Profitability: Differences in productivity will be quantified by harvested produce weights of kale crops. The crop harvest will be weighed upon collection for each test and control plot. Each week the test block and control block will be weeded, timed, and total hours required will be recorded.
  4. Education: Producers will host and lead various education and outreach programs to share their findings, but also encourage a new wave of small scale farmers. Activities will include workshops, field days, demonstrations, informational pamphlets, and a podcast recording. 
  • April 2022: Purchase supplies, initial soil test, build/plant test beds with workshop #1 with        Mountain Roots Education
  • April - October 2022: Collect data on weed survey, harvest weight, and weeding labor hours
  • July 2022: Workshop #2 with Mountain Roots Education
  • August 2022: Field day with Summit School, and worm study.
  • September 2022: Workshop #3 with Mountain Roots Education
  • April - October 2023: Collect data on weed survey, harvest weight, and weeding labor hours
  • June 2023: Demonstration with University of Idaho Extension at community garden, distribute informational pamphlet
  • October 2023: Collect second soil sample and send to University of Wyoming
  • September 2023: Presentation with Teton Food and Farm Coalition
  • September 2023: Final report and podcast with No Till Growers

Gantt Chart SARE 2022 - Sweet Hollow Farm


Click linked name(s) to expand/collapse or show everyone's info
  • Josh Arthur - Producer
  • Brian Maisenbacher - Technical Advisor
  • Toby Smith (Researcher)


Materials and methods:

Our goal was to evaluate the ability of cardboard layering and deep-mulch (CLDCM) to help improve the sustainability and profitability of a small diversified farming operation. Previous SARE grant funding recipients have conducted research on the efficacy of this practice, but the collected data has been predominantly qualitative; this project looked to provide additional quantitative, or measurable data to add to the body of knowledge that fits underneath the no-till umbrella. To achieve this goal three research objectives were addressed during the project period.


Study design: The study took place on eight vegetable production beds, each 30 inches by 100ft. Each bed was randomly assigned as either a test bed with the CLDCM treatment or a control bed using tillage and other traditional practices used by Sweet Hollow Farm. Each bed was treated as one replication, with four replications of each of the two treatments. Measurements of weed density, labor inputs, yields, and soil health were composited across each bed and averaged across the four replications.  Additionally, soil samples were collected at Foraging Farms from four replicated CLDCM beds at the end of the study. Soil type is similar to Sweet Hollow farm so this allowed analyses of affects after seven years of the no-till treatment. With four replications we were able to analyze  the variability of measurements. Brian Maisenbacher with Earthgrower assisted with statistical analyses of the data.


Test Production Bed: Four test beds (30in. by 100ft.) consisting of native soil overlaid with cardboard and compost were prepared in the spring of 2022. To build beds, blank cardboard slip sheets measuring 40in.x 48in. were laid with at least 1ft. overlapping, and then covered with 4-6in. of compost. The compost is an organic commercial mix from Mountain West Products. Pathways were mulched with 4in. of woodchips. Beds and pathways were covered with 4' rows of landscape cloth. Total preparation time for this was 25 hours to lay cardboard and compost and then an additional 2.5 hours to lay weed fabric and drip lines. Planting took 8 hours.


Control Production Bed: Four control beds (30in. by 100ft) consisting of tilled native soil was shaped into beds. Beds and pathways were covered with 4' rows of landscape cloth. Preparation time was 1/2 hour of tractor work along with 2.5 hours to lay drip lines and cover with landscape fabric. It took 4 hours to plant.


In the first year, both control and test beds were transplanted with winter squash. In the test beds, the crops needed a small hole, or dibble, through the cardboard so they can reach the native soil. In the control beds, the same size hole was made and a handful of the same compost will be added. Because the cardboard layer is intended to act as a solid weed suppression, root crops and direct seeded crops are not advised in the first year as they cannot access the native soil and will result in stunted growth. We planted winter squash in each of the 8 beds, with 48in. spacing. They were both irrigated using drip lines on similar schedules and consistent durations throughout all production beds.

Progress Photos

For the second year of the study, the plots were continued in a similar fashion. The control beds we re-tilled and the test beds were left as is. Each of the 4 beds per block were transplanted with 3 rows per bed of onions/shallots out of a 128 cell. Each row of the test and control beds had a different variety planted. Overhead irrigation was used.

wsare onions progress



1.Weed management: Each week the time required to weed the test block and control block was recorded and total labor hours required for each  calculated. In year 1 we opted to cover the beds with landscape fabric. This decision was made because of the severity of our weed problem. It was determined that this crop succession will yield more accurate and repeatable results for like minded farmers. In turn no data was collected. 

In the control bed a stirrup hoe was used to scratch and remove weeds present. In the test bed, the bindweed that penetrates the cardboard was dug up, extracting as much of the root system as possible. Because these tasks required different tooling and overall strategies we  also looked at weed ground cover density. Weed density in each weed management technique was recorded at the end of the second year. *See additional for weed density visual.


2. Soil Health Monitoring: In the transition to the zero-tillage CLDCM approach, we monitored changes in soil health by quantifying chemical, physical, and biological soil properties including soil health indicators recommended in Stott (2019).

We collected soil samples at the beginning of spring 2022 again at the end of the study in the fall 2023. In both the control and the CLDCM treatment, an 18-inch long JMC soil core was inserted 8 inches into the native soil. For the test bed the core was inserted through the compost and cardboard layers and 8 inches into the mineral soil below and sample was taken. Each bed was sampled 10 times to form a composite sample which was placed in a 1-quart sealable plastic freezer bag and immediately placed on ice in a cooler. The samples were transported back with Brian to be analyzed in his lab.

Physical properties  analyzed on soil samples included soil texture, stable aggregate content, and resistance to penetration. Soil texture was measured using a sedimentation test to quantify sand, silt, and clay content. Stable aggregate content was tested using a slake analysis. One TBSP of soil was dropped in a basket with 1cm submerged in water and a timer was to see how long took to dissolve.
Samples sat for 2 minutes before data was collected. The percentae of soil left was logged as the aggregate stability.
  Resistance to penetration was measured at the start of the project as well using a depth increment penetrometer pushed as deeply as possible into the soil. This provided baseline data and the same protocols were repeated fall 2023.

Chemical properties were analyzed using a Mehlich-3 extraction method through Logan Labs. The
Logan Labs complete soil test plus extra includes PH, organic matter, base saturation, total exchange
capacity, Melich-3 extractable sulfur, phosphorus, calcium, magnesium, potassium, sodium, boron, iron,
manganese, copper, zinc, aluminum, and estimated nitrogen release. This provided baseline data and the same protocols were repeated in the fall 2023.

Biological soil properties were measured using a microbial density and diversity analysis. Microscopy
techniques and protocols set by Dr. Elaine Ingham were utilized to determine estimations of bacterial
biomass, fungal biomass, actinobacteria, protozoa, amoeba, nematode, and microarthropods. We
also performed in-situ counts of earthworms and other soil mesofauna. This provided baseline data and the same protocols were repeated in the fall 2023.


This sampling protocol resulted in  2 treatments x 4 replications = 8 samples at each sampling period. 8 samples x 2 periods = 16 total soil samples from Sweet Hollow Farm. At Foraging Farm samples were collected at the study’s end, seven years after they deployed CLDCM. The sampling protocol resulted in  2 total samples from Foraging Farms.  *See additional documents for complete testing procedures.

3. Profitability/Yield: We harvested and recorded total weights for the 2022 and 2023 season in both the test and control beds. The recorded weights were analyzed to see trends in productivity for the individual beds as well as to compare levels of productivity between the test and control beds. 

Research results and discussion:


Year One

  1. Weed Managment: In year 1 of the project we opted to cover both the test and control beds in landscape cloth. This was intended to set back the bindweed and develop a more realistic crop succession. We then planned to use a less competitive crop for project year 2023, in bare soil/CLDCM beds as fellow market gardeners would do as well. Accordingly we have no quantitative data yet for weed management. In both blocks the weed density was 0 through the landscape cloth. 
  2. Soil Health Monitoring: Results attached. No conclusions were drawn as this is simply baseline data.

      SARE Soil Health Monitoring Results

  1. Profitability: For each control/test block 4 beds were planted with winter squash. We chose 4 different varieties and recorded the total harvest weight per bed. Significant yield difference were present in the kabocha bed (28% higher in control) and the spaghetti squash (40% higher in test). We also noted that 5 of the test bed delicata plants had to be replaced. This seemed to be because they were not planted deep enough to fully penetrate the cardboard. This is a common occurrence and can be problematic with this method in early successions before the cardboard has broken down.
      Acorn (lb) Delicata (lb) Kabocha (lb) Spagetti (lb)
    Control 146.3 154.8 373.2 457
    Test 139.3 153.1 291.8 642.8

    So far profitability results indicate the the CLDCM methods are not worth the extra cost and time to setup. This is inline with our hypothesis in that the test beds will only continue to improve in both production and weed control over time. 

Year Two:

    1. Weed Management: In the second year of the study the beds were uncovered from landscape fabric and weeded bi-weekly until full growth of onions was too dense. Time for weed management as well as weed density was recorded. Results show that there was a noticeable difference in weed presence. In the test bed almost no bindweed was present. The exception were the holes we had dug the previous year for soil sampling. There was however noticeable weed presence from annual weed seeds that had blown in. On average the time to weed the the test block was 55 minutes with two people whereas the average time to weed the control block was 2 hours for two people. In addition, it was noted that weeding the CLDCM beds was much more enjoyable as the weeds were removed with much less effort. Final weed density was recorded at 15% for test block and 45% for control block.                                                                                                                                                                                                 Weed density after onion harvest
    2. Soil Health Monitoring:

      Biological Comparison- The follow up microbial testing on the test plots showed lower bacteria counts than the baseline test results and comparable fungal counts. The soil is still lacking in predators for nutrient cycling such as nematodes, protozoa, and Amoebae. Low bacterial counts could be due to allium crops being grown in the plot this season. Lack of microbial predators is common in field production and not seeing them in follow up testing could be due to the quality of the compost applied in not being biocomplete.

      Chemical Comparison- The follow up chemical testing on the test plots showed lower calcium content than the baseline results, and higher magnesium and potassium; leaving a calcium deficit and excess magnesium and potassium in the soil. Phosphorus had increased to more suitable ranges as well as Sulfur and these no longer need to be supplemented currently. Trace Minerals have not made a significant change and Sea-90 Applications are still recommended annually.  The Compost used in the experiment may have provided the needed Phosphorus and Sulfur. The parent material of the soil in the area is naturally high in Potassium and Magnesium, and this is also true of the groundwater in the area. The sand content of the soil on the farm tends to leach calcium; the high Magnesium and Potassium are also taking up exchange sites on the soil's clay content making it harder to hold Calcium.

      Physical Comparison- Follow up testing did not show any significant increase in Organic Matter or Aggregate Stability. Sand, Silt and Clay percentages remain the same. Penetrometer data from follow up testing does show signs of increased compaction in certain areas of the control and test bed but the results are not conclusive on the entire growing area. The compaction layer could potentially be correlated with high potassium and magnesium content as well. 

      Project Final Report

    3. Profitability: For each control/test block the 4 beds were planted 4 different varieties of onions or shallots. We chose 4 different varieties and recorded the total harvest weight per bed. Significant yield difference were present in the all of the test beds. It was clear visually and through harvest logs that the no-till beds performed better, percent increase included in table.
        Patterson Yellow (lbs) Bridger Yellow (lbs) Cabernet Red (lbs) Conservor Shallot (lbs)
      Control 366.4 372 448.6 422
      Test 659 734 559.4 434.6

      Percent increase            80%                                    97%                                   25                                      3%

Participation Summary
1 Producers participating in research

Research Outcomes

Recommendations for sustainable agricultural production and future research:

Overall the project was a success. We saw a significant decrease in weed pressure and harvest yields in our CLDCM test block. In year one we saw an increase in total harvest weight of 95lbs of winter squash. Valued at $6/lb this is equal to $570 in increased revenue. In year two we saw 778 additional pounds of onions at $3/lb leading to an increase of $2,334 in revenue. Additionally we cut our weeding time by half. This was in-line with our hypotheses and we expect the results to only continue to improve.

In terms of soil health, this study still leaves much room for additional research. We were surprised to not see much a difference in biological counts in the samples of both the test and control blocks. However, it is possible that the study period wasn't long enough to document high level soil organisms as they take time to develop. Further testing is needed in better gauging soil health and no till systems and it is recommended by Technical Advisor to explore the addition of homemade biological and mineral amendments.

However, these results prove extremely impactful for sustainable agriculture. As mentioned, for many growers space is the limiting factor as land access continues to be a major challenge. The CLDCM system has proven to help small farms become more profitable and help them become more a sustainable operation. In additional this method has given us and fellow growers hope in dealing with bindweed. We have seen and heard feedback that this method has shown promise where many others have failed. This has drastically increased our quality of life and enjoyment of farming.

1 Grant received that built upon this project
1 New working collaborations

Education and Outreach

1 Consultations
1 Journal articles
3 On-farm demonstrations
1 Published press articles, newsletters
4 Tours
3 Webinars / talks / presentations
3 Workshop field days

Participation Summary:

32 Farmers participated
3 Ag professionals participated
Education and outreach methods and analyses:

One of our objectives of this project was to include community members and other growers in the process of building and studying CLDCM beds throughout the season in order to encourage a wider application of this practice. The following education and outreach activities have been completed.

May 2022: With the help of volunteers we constructed the cardboard test and control plots. There were some scheduling difficulties that did not allow us to make this a formal workshop as outlined in our proposal. However we still completed the task and educated the community on the benefits of a no-till system. 7 community members joined.

June 2022: Sweet Hollow Farm welcomed the University of Wyoming Beginning Farmer and Rancher Program for a tour and to explain our methods of no-till agriculture. We discussed the pros and cons of CLDCM methods and explained the study that was taking place. Students helped harden off the squash seedings that were soon to be transplanted in the control and test blocks. 12 students and 3 staff attended.

August 2022: Sweet Hollow Farm in partner with Foraging Farmers hosted a no-till workshop though Mountain Roots Education. This workshop focused on the importance of keeping soil covered and biodiversity on the farm. Attendees were able to see what a CLDCM plot would look like 4 years later and how the system progresses. 6 community members joined.

November 2022: Project PI was contacted by a writer at WSARE to highlight this project as part of their newsletter. An on phone interview was conducted  and photos were sent so explain the project in further detail. The article was published online and in print.

February 2023: Sweet Hollow Farm owner Jonah Sloven was interviewed for the Western SARE podcast. He discussed this project and how WSARE has helped grow their operation while supporting small growers.

April 2023: Sloven traveled to Central Wyoming College to facilitate building their own CLDCM beds in their student plot. 10 students and 3 faculty attended. This was also part of their Research to Grassroots project.

May 2023: Sweet Hollow Farm owner Jonah Sloven was interviewed for the no-till growers podcast. He shared his farming methods including CLDCM , and shared the results of the project so far. As of then they have 75k followers.

June 2023: Sweet Hollow Farm welcomed the University of Wyoming Beginning Farmer and Rancher Program again for a tour and to explain our methods of no-till agriculture. We discussed the pros and cons of CLDCM methods and explained the study that was taking place. Students helped weed in our no-till CLDCM greenhouse. 12 students and 3 staff attended.

August 2023: Community members came for an informal CLDCM workshop to learn the process for building, planting, and harvesting using this no-till method. Onions and shallots were harvested and weights documented. 9 community members joined.

September 2023: Sloven traveled to Central Wyoming College again to help with harvest and instruct on putting their farm to rest. This was also part of their Research to Grassroots project. 7 students and 2 faculty attended. This was also part of their Research to Grassroots project.

Education and outreach results:

Qualitative data shows a significant interest in the related topics. Our workshops were popular and participants were highly engaged and often staying late to continue asking questions. 100% of survey responses indicated improved awareness and new knowledge! 70% of producers were going to adapt the practice shown. 4 past participants have already initiated their own CLDCM beds.

The podcasts and newsletter article have also led to information disseminating and an increased interest. Since the project began we have received 4 emails and 3 phone calls from other producers who found our research meaningful. In addition, I have shared photos and updates on a farming Facebook group and received over 50 comments with people who were wanted to learn more. 

22 Farmers intend/plan to change their practice(s)
4 Farmers changed or adopted a practice

Education and Outreach Outcomes

Recommendations for education and outreach:

Further hands on training and a visual teaching guide would be helpful to reach both local participants and those are interested in CLDCM methods but unable to visit Sweet Hollow. Multiple stakeholders have been surprised to hear that this method can be implemented on a commercial level. It has been come apparent that further testing and ecucation in a high-tunnel. system would be beneficial for growers as that space offers the most $/sqft revenue potential.

Overall this project has had a greater reach than expected. Sweet Hollow has been contacted regarding their study and Jonah has been able to stay relevant as an educator. This has strengthened his business and operation allowing  him to have additional work on projects and panels during the off season.

2 Producers reported gaining knowledge, attitude, skills and/or awareness as a result of the project
Non-producer stakeholders reported changes in knowledge, attitudes, skills and/or awareness as a result of project outreach
10 General public
12 Students
Key changes:
  • Soil preparation

  • Soil Health

  • Management techniques

Information Products

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.