Improving cost-effective testing and actionable understanding of holistic soil and plant nutrition for agroecological farmers

Project site: Te Kwe A'naa Warep Farm, referenced as 'TKAW", (formerly known as Ma Da Dil Farm), meaning "Honor Mother Earth" in the Ramaytush Ohlone language, includes approximately 15 cultivated acres and an 8-acre farmcenter (see sitemap). Downslope, there is a riparian conservation area along the approximately 4,600 feet of creek frontage along San Gregorio Creek which has been identified as a top priority watershed for steelhead recovery.

Objective 1: Over 4 years, improve evidence-based understanding of the relationship between healthy soil and nutritious crops using holistic soil and plant testing in composted, cover-cropped, no till fields

Methods:

• We spent year one of the project in transition, adjustment, and irrigation infrastructural build out mode. First, we transitioned responsibility of the SARE project from our initial and now former PI Flor Revolorio to the current PI jibril kyser. We also engaged in our first season farming at the site. This was the Deep Medicine Circle's first year of agricultural production at the farm after acquiring the farm lease in 2021. We were able to finish building our irrigation and water storage system which will allow us to grow crops;  During year 1 of the SARE project, we were able to order the research materials listed as well as a soil auger which will be used to collect samples. We also formulated a crop rotation plan and chose 2 of the 1/4 acre research plots within the 8 acre farm center to grow winter squash and dry beans. This preparatory step put us in an advantageous position to to address compaction in our future research plots and prepare to take samples at the start of year 2 growing season. We were not able to take any first season samples because we were not able to grow the crops outlined in our project description. we did not have the post harvest handling process infrastructure, water availability, or labor support to plant out, harvest, and process winter squash and dry beans. 
• Starting in the year 2 of project period, implement holistic soil and plant testing in plots of 2 crops of cultural significance with significantly different lifecycles and nutritious values: winter squash and beans. 
  • We did not perform any baseline soil samples or first year tests. We did not do this because we did not have the capacity to take the samples at the start of the season due to the aforementioned constraints. We also did not want to take soil samples mid project year when we did have capacity because that was not in alignment with our original crop timing and soil sampling plan. We will be taking samples after we prepare the beds and soil for planting in accordance with our preparation and sampling methodology. 
  • Both crops will have had cover cropping integrated the season before, commercially-sourced compost application, and will be transitioned to no till in years 3 and 4 after we address extreme soil compaction through an initial key-line plough and spading in year 2. The soil is currently too compacted to grow any crops without primary tillage. We came to this conclusion after opening up other fields for annual cropping.
    
  • Testing will occur at 3 time periods: (1) before planting, (2) period of peak biomass time & water demand, and (3) at harvest
    • Winter squash test timing: (1) May-early June; (2) mid-August-mid-September; (3) October
    • Beans test timing: (1) May-early June; (2)  mid-July-August; (3) September
  • Testing will be for biotic, physical, and chemical properties of soil and nutrient content of the focal crops
    • Biotic testing will measure soil respiration using Solvita’s Basic Field CO2 test in 8 locations per plot. Soil respiration can be used as a measurement to assess breathing microbes in the soil as well as amount of organic matter. 
    • Physical testing will measure water-stable aggregates that are key to carbon, water and nutrient retention using Solvita’s Volumetric Aggregate Stability Test, same locations as above
    • Chemical properties of soil will be assessed with Waypoint Analytical using Bray & Mehlich III and Olsen test, same locations as above. 
    • Plant nutrient testing will measure micro and macro nutrients in crops using Plant Sap Analysis with Advancing Eco Agriculture, same locations as above
• Starting in Year 2, collect data on total yield of focal crops
• Repeat Years 3-4

Materials

• Basic Field CO2 test - 1 kit per testing round (3x/yr in 2 plots)
• Volumetric Aggregate Stability Test - 1 time licensing purchase
• Bray & Mehlich III and Olsen test, bundled sample (3x/yr in 2 plots)
• Plant sap analysis, 8 individual sample (2x/yr in 2 plots) 

Objective 2: Over 4 years, investigate holistic soil and plant health testing options in order to establish a working methodology that is meaningful and resource-effective for regional farmers

Methods

• In Year 1 of project period, conduct 8-month review on working methodology for testing: (a) soil nutrients, (b) soil biota, and (c) plant nutrients in combination with each other 
  • Review of both peer-reviewed literature and published white papers
  • Research and tabulation of the commercial options available to small-scale farmers to conduct the different tests
    • Commercial options will be focused on those that explicitly support sustainable agriculture as a business and a movement
      

      We conducted a review of options and white papers where we found 7 different soil testing options. We have not gotten to the point of evaluating each option, however we do have a plan to do so. We are planning to make a data matrix that evaluates the quality and cost of each of the testing option and place that into a visual representation.

      We located the following seven soil sampling options: 

      1. A&L labs
      2. UMASS soil testing
      3. Waypoint
      4. AEA testing
      5. Redmond testing YardStick
      6.  Ward Labs
      7. UC Davis AN Lab

      
      

      1. The following information will be baseline information about how our finalized literature review will look after we've completed the total evaluation plan. 
      2. evaluate the QUALITY of the quantitative and qualitative information that these sample types give
         1. ie. does data give us total  “fungal count” with a bar graph or does it give us  metadata dna density of fungi associated with aerobic soil conditions.
            1. Looking for specific or nonspecific information
         2. rank the quality of each test type based on internal knowledge of our research team.
         3. Tests Mostly focused on soil biology
      3. evaluate the cost of each test type
         1.  rank the cost of each test type 
      4. superimpose the ranking results of both categories in a matrix to show us the highest quality test, the test with the highest impact for the lowest cost, and then the lowest quality test with the highest cost.
         1. all of this information would be valuable for farmers on a tight budget looking for good results. 
• In the latter portion of Year 1, design a working holistic methodology
• In Years 3-4, collect data on regional farmer experience about using the working holistic methodology
  • During the growing season (1x/yr), organize a focused Campesino-a-campesino testing workshop where farmers will:
    • Collect data in the field and for the lab
    • Participate in a peer discussion of feasible, cost-effective holistic testing methodologies 
  • Gather data on farmers’ experiences in using these methodologies using a modified WSARE survey (see below)
  • Invite farmers who operate within the region, 8-12 attendees to ensure robust learning and more indicative survey data
    • Invite a portion (min. 50%) of the same attendees to the Year 3 workshop to track longer-term changes

Working Holistic Prep Methodology as a Path to no-till transition:

1. Soil preparation and bed preparation process
   1. flail mow down winter cover crop with tractor 
      1. we will utilize a 4 wheel M70 Kubota tractor in planting blocks that have not been transitioned into cropping 
      2. we will utilize a bcs walk behind mower in blocks that have been transitioned to cropping already in order to reduce subsurface soil compaction. 
   2. Keyline Plough 
      1. using the m70 kubota tractor, we will run a triple shank keyline plough through the blocks that have been mowed down. 
      2. this will fracture subsurface soil compaction and allow for increase penetration of irrigation water into the soil surface.
      3. this is a critical process as research shows that addressing subsurface soil compaction prior to no till transition is a critical step.
   3. Spade
      1. We use a 6 shoe spader attached to a smaller kubota L2850 tractor to pulverize the fractured soil into smaller aggregates that can be formed into beds and then planted into. 
      2. We are careful here to monitor soil moisture.
   4. Silage Tarp
      1. Silage tarps will be placed on top of the decomposing cover crop and soil mixture that was created via the plough and spade techniques. 
      2. this will happen immediately after the spading has completed.  
         1. objectives of silage tarp 
            1. speed up the decomposition process 
            2. reduce the amount of soil carbon loss into the atmosphere via respiration
            3. reduce soil erosion from wind. 
            4. reduce water loss from evaporation and direct soil exposure to the wind and sun.
      3. silage tarps will be left on for a period of 1 week
         1. this is dependent upon the breakdown time of incorporated cover crop material. 
            1. 1 weeks is the target timing, but 2-3 weeks is sometimes necessary due to local coastal fog conditions we experience in our ecological microclimate which reduce heat needed for organic matter (OM) decomposition through solarization.
   5. Bed preparation
      1. driving over the prepared soil with the the kubota m70 to create raised beds that match the land's natural contour line. 
2. Sampling Timeline
   1. Once the entire bed preparation process has been completed over the course of 2 weeks (time for prep and tarping), We will take our soil samples to see what the nutrient content is at the time of planting. 
   2. During the peak time of photosynthesis, we will take our second set of samples
   3. at the time of harvest we will take our third set of samples. 
   4. Our first soil samples are expected to be taken in the second week of may 2023
3. Cropping Blocks
   1. We're going to plant out a quarter acre block of winter squash and a quarter acre block of dry beans.
      1. this will require 2 samples of each sample type per sampling
         1. 1 set of sampling for dry beans
         2. 1 set of sampling for winter squash
   2. We will upload our cropping map once the plants have been planted and will upload the crop rotation plan at that time as well.

Materials

• Soil respiration field test kits (2 kits per workshop, 1x/yr for 2 years)
• Volumetric Aggregate Stability Test (already purchased)
• Soil chemical analysis, demonstrated only
• Plant sap analysis, demonstrated only
• WSARE event surveys (modified, see below)
• Food/refreshments during workshop

Data collection:

1. Soil Sampling Methodology 
   1. we will take the following tests at the completion of our soil preparation process but before we shape up beds. 
      1. We will take our first round of the following samples after we complete our aforementioned soil preparation process. 
         1. Basic Field CO2 test - (1 kit per testing round)
            1. we will be harvesting soil aggregates after the preparation of soil while the soil is still moist
            2. we will place this soil into the basic field CO2 test kit and collect data after the 24 hour waiting period. after 24 hours respiration will be complete
            3. this data will be logged and ported over into our SARE Grant Google Drive
         2. Volumetric Aggregate Stability Test - 1 time licensing purchase
            1. we will collect an additional 15 random soil aggregate samples from the test plots
            2. we will evaulate the stability of these aggregates using the methodology provided to us by solvita
         3. Bray & Mehlich III and Olsen test, bundled sample which will be sent out to waypoint labs 
            1.  we will take an additional 15 samples to conduct this test
            2. samples will be bored with a 12" soil augar
            3. those samples will then be aggregated into a clean 5 gallon bucket
            4. these samples will be homogenized and then sent out to Waypoint labs within 24 hours of collection
            5. if samples are not immediately sent out the day of collection, they will be refrigerated and then sent out the next morning in a calorimeter

For Objective 1, field data will be collected at the time periods using the materials and methods above. Real-time field data and subsequent lab results will be recorded via spreadsheets created by Brodie and stored DMC’s Google Shared Drive.

For Objective 2, review and design of the working methodology will be recorded again using DMC’s Google Shared Drive. For the testing workshops, data will be collected using slightly modified WSARE surveys.

Analysis: 

For Objective 1: Data will be analyzed by Brodie who will work with kyser and Fahrer to design an appropriate analysis. Given that this is an observational set-up, we will use trend analysis to provide interpretation of potential changes over time. Even just in 3 years time, we anticipate seeing changes in soil biota, physical structure, and chemical composition as well as crop micro- and micro-nutrients. To what extent and direction these are multi-factorially correlated is one of our central research questions. 

For Objective 2: 

1. Cost-benefit analysis of holistic soil-and-plant testing methodology - This cost-benefit analysis will occur in two phases. In Year 1, kyser and Fahrer will lead on a cost-benefit analysis of the different testing methods available and their usefulness/relevancy to small-scale, regional farmers. Financial costs, time, and effort will be the main ‘costs’ analyzed whereas the ‘benefits’ will focus on alignment with farmer priorities and evidence base, ease of access relative to geography and seasonal work schedule, and other services provided. By end of Year 4, kyser and Fahrer will incorporate the survey results from the farmer testing workshops. The analysis will then be updated by the end of Year 4.
2. Predictive cost-benefit analysis for methodology use - In Year 4, Revolorio, Fahrer, and Brodie will conduct a predictive cost-benefit analysis around the use of the working holistic methodology. 'Costs’ will be the financial cost, time, and effort of the specific methodology (developed under Objective 2) whereas the ‘benefits’ will be any reductions in financial cost and environmental impact of soil amendments. Given that we will be actively learning during Years 1-3, we anticipate that additional/nuanced benefits to farmers of using this holistic methodology will emerge. We hypothesize that using this methodology will improve the efficiency of our soil and plant health management practices and have knock-on benefits to our professional wellbeing and purpose.