Compost application on rangeland in the semi-arid southwest for increased soil C storage and forage production

Final report for FW20-363

Project Type: Farmer/Rancher
Funds awarded in 2020: $19,981.00
Projected End Date: 04/01/2023
Host Institution Award ID: G355-20-W7900
Grant Recipient: Polk’s Folly Farm
Region: Western
State: New Mexico
Principal Investigator:
Zachary Withers
Polk’s Folly Farm
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Project Information


In the semi-arid Southwest, rangeland restoration is needed to ensure economically  viable agricultural operations in light of historical mismanagement of rangeland and climate change. Compost application to croplands and rangelands in mesic environments has proven successful to increase forage production and soil carbon storage, essential for soil water-holding capacity. Here we propose leveraging current compost production at Polk’s Folly Farm to assess the efficacy of compost application to rangeland for increased forage production and soil carbon storage at two semi-arid sites in New Mexico (annual precipitation ~ 460 mm). Polk’s Folly Farm and Sol Ranch collaborated with the Quivira Coalition and New Mexico Tech to assess this method at two sites with native plant communities using three application rates and a control. After one year, ranches saw improved aboveground biomass, methane uptake, and infiltration rate with compost addition. In order to provide a comprehensive picture of project efforts to producers, Polk’s Folly Farm created an economic case study of on-farm compost production. Additionally, the team held two field-days featuring the experiments and Polk’s Folly Farm and Sol Ranch discussed their experiences on Quivira Coalition’s podcast. Results were presented at the annual REGENERATE conference, where the largest attendee group is producers. Assessing the efficacy of this nationally recognized method for increasing soil carbon storage and forage production in semi-arid sites will inform producers, agencies, and technical service providers’ management decisions.

Project Objectives:

Objective 1: Determine best methods and economic feasibility of compost production on Polk’s Folly Farm

  • Produce compost with a C:N >11 appropriate for rangeland application [4,6]
    • Polk’s Folly Farm, Eva Stricker (technical advisor), Benjamin Duval (researcher)
  • Open-source, free economic case study of compost production
    •  Polk’s Folly Farm, Eva Stricker, Benjamin Duval

Objective 2: Determine appropriate compost application rate 

  • Establish 3 application rates (1/4, 1/2, and 1") and a control plot in experimental plots
    • Polk’s Folly Farm, Sol Ranch, and Eva Stricker

Objective 3: Determine compost application effect on soils and plant communities

  • Soil sampling and analyses at pre-treatment (year 1) and years 2 and 3. Plant community monitoring at pre-treatment and years 2 and 3. 
    • Lead: Eva Stricker, all team members participate
  • Analyze and interpret data for presentation at 2021 and 2022 REGENERATE Conference
    • Eva Stricker and Benjamin Duval

Objective 4: Producer focused engagement in experimental setup and the WSARE grant application process

  • Experimental design and compost application field-day
    • Eva Stricker, Polk’s Folly Farm, and Sol Ranch
  • Podcast about WSARE Farmer/Rancher Research and Education Grant process for producers
    • Polk’s Folly Farm and Sol Ranch 
  • Presentation of results at 2021 and 2022 REGENERATE Conferences
    • Eva Stricker, Polk’s Folly Farm, and Sol Ranch

Please see the link below to the pdf of our timeline:



Click linked name(s) to expand/collapse or show everyone's info
  • Emily Cornell - Producer
  • Dr. Benjamin Duval (Researcher)
  • Eva Stricker - Technical Advisor
  • Zachary Withers - Producer


Materials and methods:

Polk’s Folly Farm is a small family run operation in the Eastern foothills of the Sandia Mountains (elevation 2095m). They specialize in heritage breed hogs, and also raise a small flock of laying hens, ducks, and a few head of cattle. The average temperature is 10.6C, with highs in July of 20.1C and lows in December of -0.9C, and average precipitation of 431 mm with 55% falling between July-October (NOAA 1991-2020). Soils are Silver and Witt very fine sandy loam at the surface (Web Soil Survey). This pasture was continuously and intensively grazed by horses from 1976 through the late 1990s. The pasture was fallowed until 2014 and mowed annually. In 2015 the pasture has been intermittently grazed by cattle using temporary electrical fencing to move herds ranging in 2-8 head through small paddocks. The degraded rangeland dominated by snakeweed (Gutierrezia sarothrae) and blue gramma (Bouteloua gracilis)

Sol Ranch is a restoration-focused cattle ranch that produces grassfed beef in northeastern New Mexico , where the plains meet the mountains (elevation 1890m). The average temperature is 10.0C, with highs in July of 20.4C and lows in December of 0.5C, and average precipitation of 400 mm with 63% falling between July-October (NOAA 1991-2020). Soils are Vegocito and Gallinas clay loam soils (Web Soil Survey). Before the 1950s, the land was used year-round for grazing sheep, after which it was used to graze cattle annually.  

Compost Production and Testing

Polk’s Folly Farm produced all compost used for this project. Primary feed stocks for the compost are food scraps and wood mulch. Additional feed stocks are horse, pig, and chicken manure, cardboard, and straw. About 25,000 lbs/week of expired fruits and vegetables are sourced from Road Runner Food Bank and deposited onto a bed of C-rich material, where it is physically mixed with swine manure. When a suitable mixture and moisture level are achieved, the compost is mounded in windrows. Windrows are temperature tested daily and turned or aerated with a skid steer as needed. A minimum of 131˚F is maintained for at least 3 days on each pile, most piles sustain temperatures of greater than 160˚F for more than 5 days, and are turned at least 5 times. When piles begin to cool they are consolidated and allowed to cure for a minimum of 30 days. 

Table 1. Compost characteristics from Colorado State University laboratory.





















































































Experimental set-up

At each site, twelve 41.8 m2 plots (4.75 x 9.14 m) were established on flat, relatively uniform fields. Three plots were randomly assigned to be control plots, and three plots each received 0.64 cm, 1.3 cm, or 2.5 cm of compost which corresponds to approximately 0, 3.2, 6.4, 12.8 kg m2, respectively, which spans added amounts in previous studies (Kutos et al. 2022). Baseline monitoring (see responses below) was completed just prior to compost addition in September 2020 at each site.

In each plot, two 1 m2 quadrats for aboveground biomass clip plots were marked with railroad nails, 1 m from the edge of the narrow axis of the plot to avoid edge effects. One of the quadrats was surrounded by 4 ft tall fencing to create an exclosure within each plot. Two 5 m long transects for vegetation functional group composition were marked with railroad nails 1 m from the plot edges and 1 m from the clip plots. 


Bulk density was collected from 0-10 cm using a rigid metal cylinder (diameter X) hammered into the soil then excavated and placed in a plastic bag for transport to the lab to dry at 60C for 3d.

Aggregate stability was measured on 6 haphazardly-collected surface samples using methods from Herrick et al. YYYY. This method would not capture soils that could not be collected on the sieve (aka, category 0), but was consistent across all treatments. 

Infiltration rate was measured with a single ring infiltrometer (15.24 cm diameter) pounded into the soil in a randomly selected interspace (without perennial plants inside) to 10 cm depth. 444 mL of water was added and the time for all soil to infiltrate until soil surface was “just glistening” was recorded, up to 30 min. If the first 444 mL infiltrated within 30 min, a second 444 mL was added and the time for the water to infiltrate was recorded, up to 30 min. In 2022, we used a ruler to measured the time and depth over 3-4 time points and used a linear model to fit a regression line to then extract the time at which no water remains on the surface.

Vegetative cover and functional species richness and diversity was recorded along each transect and a pin flag was used to identify what dominant plants or ground cover intersected the transect every 5 cm in the following vertical categories: rooted or adhering to the soil surface (“ground level”), up to 50 cm (“herbaceous level”), 50 cm - 2 m (“shrub level”); no plants on the site were  >2 m. For analysis, we grouped plants into functional groups: annual vs. perennial, seedling (plants with only cotyledons up to the first two true leaves) vs. plant, and grass, forb, or woody. The litter category included fine and coarse herbaceous and woody debris and dung. Bare ground included soil and rock. 

Aboveground biomass was collected in the quadrats, both from the exclosure and in the open plot. We used a 1 m2 grid divided into 100 cm2 squares and randomly selected without replacement five squares to clip to ground level each year. Material was placed in paper bags, dried at 60C for 3d, and oxidized material was removed to capture material that was likely to have been alive in the previous 12 months. Material was weighed to 0.1 g.

Belowground biomass in the top 10 cm was collected in the same squares in the 1 m2 grid as the aboveground biomass with 0.9 cm diameter soil core. Soil was poured through a 2 mm sieve and roots were picked out from both the sieve and below (fine roots) with forceps. Roots were soaked and washed with water then dried for 60C for 3d and weighed to 0.XXX g.

Gravimetric water content was measured on soils aggregated from six 0.9cm diameter x 10 cm soil cores. Soils were sieved to 2mm and a subset of ~20g of field condition soil was placed in a tin, dried at 60C for 3d and re-weighed. 

Additionally, we partnered with Los Alamos National Labs to assess greenhouse gas fluxes in the compost and control plots using a Licor. 

Analyses were conducted in R using mixed effects models in the LMER package. 


Research results and discussion:

After 2 years, bulk density decreased with compost addition (treatment x year P = 0.03; Table 2, Figure 1). Infiltration rate was consistent across plots in 2020 during the baseline measurements then differed by site in subsequent years (Treatment x Year x Site P = 0.08; Table 2, Figure 2). After one year, In 2021, both sites showed increases in infiltration rate with compost additions (however, at Sol, the increase is not statistically different from zero; post-hoc comparisons P >0.05). The effect persisted at polks in 2022, but at Sol there was no effect of treatment. Again, potentially the interaction of compaction and compost at sol (and, lots of variability in the control plot values). There was no difference in aggregate stability with amendment treatment at polks, but significant increase in stability at sol (Table 2, Figure 3) 

Vegetative characteristics. While there was a trend that aboveground biomass increased at Polks with added compost after one or two years, the slope isn’t different from the underlying differences in the plots recorded at baseline (Table 3, Figure 4). At Sol, there was no difference in baseline plots by compost treatment. There was a marginally nonsignificant difference in biomass by treatment inside and outside exclosures, meaning the effect of compost was stronger inside the exclosures than outside which may indicate preferential grazing in compost plots. While not statistically significant, this trend is stronger in the first year (2021).  

There was a negative effect of compost amount on root biomass at Polks in first year, perhaps indicating less allocation to roots because more nutrients were available, but no significant effect at any other time at Polks or any time at Sol (Table 3, Figure 5). 

There was a significant decrease in bare ground across both sites in 2022 (Table 4; Figure 6); interestingly, there may be some non-linearity (as in, a little bit of compost results in almost as much decrease as a lot of compost), but we do not have the statistical power to test for that directly. 

Soil Carbon and greenhouse gas fluxes. There was nearly 2x as much organic C in the top 10 cm of soil after 2y across both sites (Treatment F = 26.38, P < 0.005; Site F = 0.25, P = 0.62, Treatment x Site F = 1.90, P = 0.183; Figure 7).

As expected, compost additions led to higher respiration and therefore higher CO2 emissions and both Polks and Sol saw decreased emissions or enhanced uptake of methane with upto 1” of compost (Figure 8). Nitrous oxide fluxes, however, varied by site and compost addition (Figure 9), which is points to microbe-microbe interactions of host site soils with the compost (which was the same initial pile for both sites).


Link to tables and figures:

Participation Summary
2 Producers participating in research

Research Outcomes

Recommendations for sustainable agricultural production and future research:

Compost, controlled aerobic, biological decomposition of organic feedstocks, as an organic amendment has been shown to increase productivity and various forms of carbon pools across multiple continents, time scales, and application strategies (Kutos et al. 2023, Gravuer 2019) and models suggest that even single applications will have climate beneficial effects persisting until at least year 2100 (Mayer and Silver 2022). Additional responses to compost additions include increasing water infiltration and retention, altered nutrient cycling, and reduced erosion (Kutos et al. 2023). However, questions remain regarding optimal use of compost on rangelands that differ in climatic and soil characteristics as well as management. For example, larger effects of compost on carbon pools have been observed in plots with <600mm precipitation per year (Kutos et al. 2023), and adding large amounts of compost (>20kg m-2; Kudos et al. 2023; >3cm depth; Leger et al. 2022) resulted in decreased productivity or carbon pool sizes compared to other compost amounts or, even control plots. Optimal use of organic amendments such as compost for each producer will be a balance of resource and time costs and benefits, and thus understanding the magnitude of ecological response will help range managers make appropriate decisions for lands that they steward.

In this study, we investigated how the amount of compost addition on rangelands would affect metrics related to soil health. Generally, we found that there were stronger effects on soil health, productivity, and soil carbon with more compost added, but we also found generally linear increases with the amount added. Thus producers could assess costs of different amounts and anticipated benefits of doubling amounts from 1/4 to 1/2 to 1 inch and decide accordingly what best matches their constraints and goals. 

We are anticipating submitting a manuscript for peer-review publication in May 2023. 

4 Grants received that built upon this project
3 New working collaborations

Education and Outreach

4 Consultations
1 Curricula, factsheets or educational tools
1 Online trainings
1 Published press articles, newsletters

Participation Summary:

30 Farmers participated
2 Ag professionals participated
Education and outreach methods and analyses:

We toured the Sol Ranch compost sites in July 2022 as part of the “Improving Water Availability and Conservation for Livestock & Wildlife on New Mexico’s Rangelands” workshop hosted by NRCS and Bat Conservation International (note that the Agenda has the wrong name for the Presenter and also the wrong title of the section - should be “Compost and rangeland soil health - Eva Stricker, Quivira Coalition”). We also toured the Polk’s Folly compost sites in July 2022 as part of the Composting workshops. While staff and contractors used heavy machinery to set up an aerated static compost pile, the participants and Quivira staff observed the compost experiment. At both sessions, we discussed the healthy soil principles and how compost additions align with those principles. We verbally discussed initial results and visually noted that there was more biomass in exclosures in the compost plots than in the control plots. People also observed that while much of the biomass was annual plants, there were some useful plants (eg. Kochia which is palatable to livestock), and no one noted noxious weeds besides what are already found on the landscape (eg. tumbleweed). 

In fall 2020, the project was featured in the Quivira Coalition’s monthly e-newsletter ( 

The Quivira Coalition co-produces the Down to Earth podcast with Radio Cafe.  Both Polk’s Folly Farm farm manager Zachary Withers and Sol Ranch’s Emily Cornell were interviewed on the podcast to discuss the WSARE Farmer/Rancher Research and Education grant. The podcast ran in January of 2022

 At the 2022 REGENERATE conference, Eva Stricker presented the preliminary results of the WSARE experiment. Producers (ranchers and farmers) are the largest single attendee group at the REGENERATE conference  (in 2018 40% of 590 attendees), which makes this is an ideal venue for sharing information about the project and its findings with producers. 

Eva Stricker provided an outline of grant application process as a webinar in June 2021 ( aimed at producers and other technical service providers. Eva has also been conducting one-on-one consulting with producers and TSPs about grant writing.  

Education and outreach results:

At the workshop at Polk's Folly Farm, attendees steward a total of 2230acres in NM. Attendees reported the following aspects that they appreciated about the workshop:

Open communication style, learning, community building
Space and educators
Diverse backgrounds of attendants (both instructors and students); lots of questions allowed; seeing multiple properties/faciliites
Friendly instructors, real-life experience, questions of group
Q&A: any topic welcome, Hands on learning, Listening and learning from other participants and famers, learning from walking around active farm in my neighborhood
demonstrations and exlanations
open format
the information
the "hands on" during the afternoon
The deep conversation and information with good friendly vibes. Hand-out has rich information on subject. Open conversation and demonstration of systems being experimented on.
The info and relationship building
everything and hands on

On average, participants ranked the workshop highly (1 = strongly disagree to 5 = strongly agree)

The content was communicated well and presented in an organized manner I gained new knowledge and/or built upon previous knowledge during the workshop I can apply the concepts I learned during this workshop The workshop was what I expected from the promotional materials
4.69 4.84 4.84 4.77
2 Farmers intend/plan to change their practice(s)
2 Farmers changed or adopted a practice

Education and Outreach Outcomes

Recommendations for education and outreach:

A key aspect of the experimental design that was added was that an exclosure has been constructed on each plot to enable comparison of grazed and ungrazed plants; we anticipate preferential grazing on plants in compost addition plots. 

Some concern has been expressed that the plot sizes were small relative to what will be useful in a true operation scale; luckily, sol ranch is engaged in both this research as well as on-ranch trials so we can compare the differences qualitatively in things like edge effects or amount of land treated before a change in vegetation is observed. An additional concern relates to how little we know about compost additions in dry rangelands: what is ideal timing of deployment (growing season vs. after spring windy season).

We have not yet engaged in in-person educational outreach but have shared the video on newsletters and social media and the previous version has been viewed over 250 times since October 2020. We intend to facilitate peer-to-peer learning about how compost can relate to soil health, leveraging existing region-appropriate content such as the Soil Health Workbook (

2 Producers reported gaining knowledge, attitude, skills and/or awareness as a result of the project
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.