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

Progress report for FW20-363

Project Type: Farmer/Rancher
Funds awarded in 2020: $19,981.00
Projected End Date: 04/01/2023
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

Abstract:

In the semi-arid Southwest, overgrazing and mismanagement of rangeland, combined with climate change, are necessitating rangeland restoration  to ensure economically viable agricultural operations. Compost application to croplands and rangelands in wetter environments has proven successful to increase forage production and soil carbon storage, essential for soil water-holding capacity. Here we propose leveraging efforts 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 will collaborate 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. In order to provide a comprehensive picture of project efforts to producers, Polk’s Folly Farm will create an economic case study of on-farm compost production. Additionally, the team will hold a field-day on experimental design and compost application methods. To encourage producer participation in the next round of WSARE Farmer/Rancher Research and Education grants, Polk’s Folly Farm and Sol Ranch will discuss their experience with grant application and execution process on Quivira Coalition’s podcast. Results will be 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

Cooperators

Click linked name(s) to expand
  • Emily Cornell - Producer
  • Dr. Benjamin Duval (Researcher)
  • Eva Stricker - Technical Advisor
  • Zachary Withers - Producer

Research

Materials and methods:

Experimental sites on Polk’s Folly Farm and Sol Ranch have been selected based on the following criteria:

(1) producers would like to see an increase in forage productivity and/or restoration of degraded rangeland

(2) uniform soils and slopes

Site Descriptions

Polk’s Folly Farm (2035 m) in central New Mexico experiences average annual precipitation of 431 mm with an average daily temperature of 6.9˚C [7]. Experimental blocks will be located in degraded rangeland dominated by snakeweed (Gutierrezia sarothrae) and blue gramma (Bouteloua gracilis), on an aridisol with a very fine sandy loam profile (5 to 9 % slopes) [8]. 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. 

Sol Ranch (1890 m) in northern New Mexico experiences annual average precipitation of 413mm with an average daily temperature of 6.9˚C [7]. Experimental blocks will be located in a dry grassland on aLa Brier silty clay loam (0-3% slope) [8]. 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 will be responsible for compost production; they already have an established composting operation. 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. Once cured, the compost will be tested by Benjamin Duval (researcher) to determine that the C:N is > 11, as this is the most appropriate ratio for dry rangeland application [6]

On-site compost production and testing will allow us to address objective 1, and is essential for completing objectives 2 and 3.

Block Plot Compost Application

Polk’s Folly Farm, Sol Ranch, and Eva Stricker will be responsible for establishing the experimental plots. We will rely on Polk’s Folly Farm’s hydraulic dump trailer to deliver compost to Sol Ranch. 12 plots will be established on each site. Plots will be assigned to one of 4 treatments (1/4″, 1/2″, 1″ compost application rates and control) that are ~5m x 10m, with 5 m alleys between the plots. Within each plot, a 1 m exclosure will be established to test for effects of grazing x compost. Compost will be applied in August/September 2020, during the primary growing season. 

This experimental design will allow us to address objective 2, determining the appropriate compost application rate. 

Soil and Plant Testing and Monitoring

Polk’s Folly Farm, Sol Ranch, Eva Stricker, and Benjamin Duval will all be involved in soil sampling and plant monitoring, and Benjamin Duval will be responsible for soil analysis. In August 2020, we will collect baseline soil samples in order to characterize the physical and chemical properties of the soils. We will sample each plot in triplicate at at 0-15cm for the following physical and chemical properties: pH, texture, water-holding capacity (field capacity and wilting point), TOC, TN, C:N, infiltration rate, water stable aggregates, and soil C storage (density fractionation for free light and occluded light, and heavy fraction). At each block plot we will also collect bulk density at 0-8 cm to convert C and N concentrations to content (mg C or N ha-1). To determine the effects of compost addition on forage production, we will monitor above-ground net primary productivity as with line intercept transects and clip plots/root cores. The soil and plant data outlined above, except for soil texture, pH, and bulk density, will be collected annually over the course of 2 years, at the end of the growth season in September. 

These data allow us to address objective 2 and 3. We will determine the effect of compost application on forage production via our above-ground net primary productivity measurements. We will determine the effect of compost production on soil water infiltration and retention along with C storage. Analysis of all response variables by application rate will determine the best application rate for these rangeland systems. A change in soil C storage is likely to be observed over a longer time frame [2] than the granting cycle, and we intend to continue monitoring soil C storage after the granting cycle is complete. 

Research results and discussion:

Baseline data available so far revealed that the 12 plots at each site were initially quite similar in soil physical properties (bulk density (g/core) at Polk’s = 248.44 +/- 3.48SE; Sol = 291.04 +/- 3.84SE; aggregate stability at Polk’s = 2.22 +/- 0.17; Sol = 2.48 +/- 0.13) and biological properties (aboveground biomass (g/m^2) at Polk’s = 44.7 +/- 9.9; Sol  = 118.3 +/- 2.17; Respiration rate from Solvita kit; CO2 evolved at Polk’s = 1.875 +/- 0.24. 

Participation Summary
2 Farmers participating in research

Educational & Outreach Activities

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

Participation Summary

Education/outreach description:

One on-farm/ranch field day will be held in 2021 or 2022 to engage producers in experimental setup and compost application. Polk’s Folly Farm and Sol Ranch have both held workshops and/or field days, and we will leverage these networks for attendance. Furthermore, Quivira Coalition specializes in rural, participatory education projects and has built a reputation for demonstrating low-impact, high-reward, applicable, and actionable land management practices in its outreach activities. Polk’s Folly Farm or Sol Ranch will be the field-day hosts and main instructors, and Eva Stricker will also be an instructor. At the field day, we will discuss how to design monitoring strategies for land management decisions to improve soil health and address issues around balancing daily production activities with time and monetary constraints and statistical power. With field day participants, we will also spread the compost on the treatment plots and talk about why we took the baseline measurements that we did. 

In fall 2020, once established and following the on-farm/ranch field day, the project was be featured in the Quivira Coalition’s monthly e-newsletter (https://mailchi.mp/quiviracoalition/august-enews). We will also provide e-newsletter readers with annual project updates in 2021 and 2022, and beyond. The economic case study that Polk’s Folly Farm will provide for compost production will be available to fellow producers as a template and starting point for implementation on their own operations. The case study will examine both technical (materials, machinery, production process) and economic (cost of production, opportunities for sale, waste diversion, nutrient cost off-sets) areas, and will be completed by Polk’s Folly Farm with support from Quivira Coalition.This case study will be provided for download on the Quivira Coalition website (www.quiviracoalition.org) and will be promoted 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 will be interviewed on the podcast to discuss the WSARE Farmer/Rancher Research and Education grant application process—from coming up with an idea to working with a technical advisor to pressing the submit button to executing the project. The podcast will be run in September of 2021, allowing farmers and ranchers enough time to complete the open application for WSARE Farmer/Rancher grants by the November 2021 deadline.

 At the 2022 and 2023 REGENERATE conferences—hosted jointly by the Quivira Coalition, Holistic Management International, and the American Grassfed Alliance— Polk’s Folly Farm, and Sol Ranch will hold information sessions about the use of compost to restore rangeland, including presentation of the preliminary results. 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. 

These educational and outreach activities will allow us to address objective 4, which focuses on producer engagement in the research aspects of the project, and it will also help lower the barrier for producers to accessing WSARE funds for projects.

Learning Outcomes

2 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

2 Farmers changed or adopted a practice
2 Farmers intend/plan to change their practice(s)
3 Grants received that built upon this project
3 New working collaborations
Project outcomes:

Due to Covid19, we have not been able to reach out directly to community members for site visits or  workshops. Thus, we currently only have 2 ranchers (Polk’s Folly and Sol Ranch) that intend to and have changed their practices, namely by implementing the experiment on their active rangeland. 

 

Three grants have built upon this project, including a compost trial on Santa Ana Pueblo and Southwest Indian Polytechnic Institute, an on-farm trial (NRCS funded) with three ranches (including Sol Ranch) of compost, biochar, and bale grazing, and a research proposal (USDA AFRI to University of New Mexico) investigating microbial community impacts on compost success. 

 

Additional collaborations have been made with instructors and researchers at Highlands University near Sol Ranch, with plans to bring students for field trips and research experience, and with Desert Forge, a non-profit building agricultural workforce from returning veteratns. They have been working with Polk’s Folly to be trained in all aspects of the swine and compost operation. A final collaborator was a filmmaker who made a short film about deployment: https://youtu.be/QcEaRoqXkSU

 

This project has affected agricultural sustainability by bringing awareness to the need to actively restore rangelands that may continue to degrade if just rested. Polk’s folly has invested in a manure spreader based on interest and anecdotal evidence of the compost success and builds capacity for them and their neighbors to use compost on working lands. Because compost was deployed during the growing season and there has been a severe drought throughout the entire year, little environmental effect has been observed so far, but we are anticipating improvements in water retention and better productivity in the 1 year monitoring. 

 

This project has built substantial capacity of monitoring and sample processing for farmers and ranchers as well as intern undergraduate/graduate students through Quivira Coalition and New Mexico Tech. Ranch personnel were trained in monitoring protocols and assisted with all aspects of set-up. Interns from Quivira assisted with data collection and data management and one intern, (Davis) led the total cost analysis (draft awaiting copyediting and then will be provided freely on the Polk’s Folly and Quivira Coalition websites; meanwhile available here: https://docs.google.com/document/d/1eCTd85uAxAW68eD-YQllxTV0OsuVEiwaZlIlaPpBoSs/edit#). 

Baseline data from 12 plots at each ranch (24 plots total) has been collected about bulk density, infiltration rate, surface soil aggregate stability, vegetation community and surface cover (transect method), aboveground biomass (clip plot method), compaction, respiration rate, as well as soil and compost chemistry. Each plot has been photographed for repeat photography. 

The social benefit has been considerable, tightening the connection between Sol Ranch and Polk’s Folly; Sol has been selling ground beef at Polk’s Folly Farm Stand, and they have been exchanging information about meat processing slots available. 

Success stories:

Sol Ranch received the Excellence in Range Management in Feb. 2021, partially due to willingness to engage in research and outreach as well as hosting an apprentice (8 months) interested in learning more about agricultural enterprise. 

 

Recommendations:

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 (https://quiviracoalition.org/soil-health-workbook/)

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.