On-Farm Testing of Johnson-Su Compost Extract as a Biological Inoculant in Wheat and Soybeans

Progress report for ONC23-119

Project Type: Partnership
Funds awarded in 2023: $49,846.00
Projected End Date: 03/31/2025
Grant Recipient: MN Wheat Research and Promotion Council
Region: North Central
State: Minnesota
Project Coordinator:
Melissa Carlson
MN Wheat Research and Promotion Council
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Project Information


High yielding wheat and soybean crops require high amounts of applied N and P fertilizer. We will determine if fertilizer rates can be reduced by using furrow-applied Johonson-Su bioreactor compost extract. We hypothesize that this extract will inoculate the soil with beneficial microorganisms to work symbiotically with crop roots to supply additional soil nutrients that are inaccessible by the crop. This could immediately benefit farmers by reducing their fertilizer needs and improving the health and biological activity of their soil. Reducing fertilizer use while maintaining farm profitability is a huge hurdle that must be overcome as industrial agriculture moves towards more environmentally sustainable methods of production. We will test the compost extract at scale with our cooperating farmers to determine if this homemade biological inoculant is economically profitable and can reduce fertilizer needs. We will also conduct small plot trials to assess the effect of compost extract inoculation with varying levels of fertilizer to determine the optimum amount of fertilizer needed with and without compost extract. We will share these results in various grower meetings and printed and electronic publications hosted by both the MN Wheat Council and the UMN to reach producers in MN, ND, SD, and eastern MT.

Project Objectives:

At the conclusion of this research, we aim to:

  1. Demonstrate methods to economically create and use a Johnson-Su Bioreactor on a commercial crop farm to wheat and soybean
  2. Determine if N and P fertilizer can be reduced by using compost extract applied in-furrow at planting 
  3. Evaluate fungal and bacterial species diversity and quantity in compost extract 
  4. Educate regenerative and conventional farmers about the principles and methods behind the compost extract application to wheat and soybean and how to replicate the process on their own farm


Click linked name(s) to expand/collapse or show everyone's info
  • Lindsay Pease - Technical Advisor (Researcher)


Materials and methods:


  • 4 Bioreactors were built by hanging bulk seed tote bags inside the cages of bulk shuttle totes, and hanging 5 perforated sewer pipes inside the tote to serve as the air chimneys. The bottom 6-8 inches of the inner plastic bladder were cut out and placed back inside the cage to catch any excess leachate from potentially overwatering the bioreactor. Pallets were cut to fit inside the cages and placed inside the plastic liner, below the tote bags to allow extra water to drain out of the tote bag and into the cut out bottom of the plastic bladder, which could be drained using the shuttle tote's ball valve if too much liquid accumulated
  • Compost materials included a mix of approximately 50% rye straw chopped with a bale processor, 10% partially decomposed wood chips, 10% mulched oak leaves, and 20% horse manure mixed with hay. The manure was free of dewormer, and the straw was free of chemical residues. 
  • Materials were mixed together in a wheel barrow, then transferred to laundry baskets and submerged in water until they were sufficiently soaked, drained for a few minutes and then  distributed around the chimneys inside each of the bioreactors
  • An automatic sprinkling system was setup using garden irrigation drip line and an automatic timer for garden hoses to keep the compost moist. Bioreactor compost was also partially covered using scrap pieces of landscape fabric to reduce evaporation. 
  • The bioreactors went through their heating cycle over the course of the first week and peaked at about 130 F
  • After the bioreactor internal temperature dropped back down below 80F, approximately 2 lbs of red composting worms were added to each bioreactor. 
  • Bioreactors were maintained in heated shops above 60F throughout the remainder of the year, adding water as necessary to maintain moisture so that the compost wasn't overly drenched, but a handful of compost squeezed in the hand could squeeze out a drop of water


Extraction and Application

  • Fed N Happy worm castings were used in place of Johnson-Su compost in the 2023 growing season, since we did not have access to suitable Johnson-Su compost for the first year. We went with worm castings since the Johnson-Su process with worms essentially results in matured vermicompost, and Fed N Happy's  method of raising worms would result in a similar product suitable for comparison. A BeCrop DNA analysis of the worm castings revealed about 848 species of bacteria and 137 species of fungi present in the castings. 
  • Extract was initially made for the small plot research and the wheat seed treatments by vigorously bubbling 2 lbs of worm castings/gal in a 5 gal bucket using a circular lawn sprinkler attached to an air compressor at approximately 15-20 psi for at least 30 min. The extract was filtered first through a 5 gal paint filter, and then through a finer cone paint filter (micron/mesh size unknown). The extract for the on-farm field plots was additionally run through a system of T-line filters attached to a small sprayer pump set up by one of our cooperating farmers fitted with a 30 mesh and a 50 mesh filter. 
  • Wheat seed was treated by spraying the filtered extract onto the wheat seed as it was being augered from a truck to the seed tender/gravity box at a rate of 9 0z/cwt, which is a similar volume rate for commercial seed treatments. Wheat seeds were covered and thouroughly mixed by augering, but were not so wet as to cause bridging or clogging problems. A 60 gal mixing cone held the extract and was attached to the T-line filter/pump sprayer set up with a fine nozzle tip. 
  • An additional sunflower plot used a liquid in-furrow drip application at planting instead of a seed treatment. For this extraction, we used 1/3 lb compost/gal, applied at a rate of 6 gal/acre to reach a the rate of 2 lbs compost applied/acre suggested by David Johnson. Compost was again first bubbled inside a 5 gal paint filter hung inside a 60 gal mixing cone. A trash sump pump was also hung inside the mixing cone with a 1.5 inch hose attached, which was used to circulate and agitate the water and compost during the extraction. The initial extract was run through the T-line filtration set up and filtered down to 50 mesh before being transferred to the air seeder's [rinsed] starter fertilizer tank

On-farm Plots

  • At planting, wheat plots were fertilized with their respective fertilizer treatments using a pull-type spreader or the coop's spreader. The Johnson-Su treated plots were planted first with the treated seed, and then the untreated plots were filled in afterwards with regular untreated seed. 
  • The sunflower plot was planted normally and without any fertilizer treatments, just turning the liquid system on and off through the respective treated and control plots as the field was planted.
  • All plots were flagged and marked with GPS at planting
  • Tissue samples were collected at late boot/early flag leaf stage in the wheat sites
  • Plots were harvested with the grower's combine and weighed in a weigh wagon. Grain samples were collected to test moisture, test weight, and protein content.
  • Soil samples were collected after harvest for nutrient analysis and PLFA testing
  • Treatments were applied as follows:
  1. Control – Farmer fertilizer rate, no extract
  2. Compost extract + ½ N rate + 0 P
  3. Compost extract + 0N + 0P

Small Plots

  • Wheat and soybean small plots were set up as randomized split-plots, with the worm casting extract as the main plot and fertilizer treatments as the sub-plots. The wheat plot was replicated 3 times, and the soybean plot was replicated 4 times as field space allowed. 
  • Wheat seed was treated with extract while the soybean plots received an in-furrow application. The extract was made by bubbling in a 5 gal bucket as described above, following the compost and application rates as described above for either the seed treatments in the wheat or the in-furrow rate for the soybean plot. 
  • Tissue tests were collected at late boot in wheat and 3rd trifoliate in soybean
  • Plots were harvested with a small plot combine by the U of MN Crookston plot technicians. Grain samples were collected to test moisture, test weight, and protein content.
  • Soil samples were collected after harvest for nutrient and PLFA analysis
  • Treatments were applied as follows:
    • 0, 60, 120, 180 lbs N; with compost extract (wheat only)
    • 0, 120, 180 lbs N; no compost extract (wheat only)
    • 0, 20, 40, 60 lbs P2O5; with compost extract (wheat and soybeans)
    • 0, 40, 60 lbs P2O5; no compost extract (wheat and soybeans)

Bottom 6 inches of bladder cut out to contain leachate
Pallet cut to fit inside bladder cutout to hold up tote bag to allow drainage


Wood chips
Partially decomposed woodchips for compost feedstock
Soaking and draining compost feedstock
Soaking and draining compost feedstock
Filled bioreactor with irrigation setup
Measuring worm castings
Measuring worm castings
Small batch agitation
Small batch agitation
Agitation psi
Agitation psi
Compost in paint filter
Compost in paint filter
Calibrating grain flow for seed treatment
Calibrating nozzle output for seed treatment
Seed treater mixing cone
Filter/sprayer pump setup with seed treatment nozzle

T-Line filter set up with seed treatment nozzle

Seed treatment
Transferring seed from truck to seed tender to mix treated seed
Seed treatment
Treating seed after flow calibration
Trash pump circulating water through compost
Filtering in-furrow extract
Filtering in-furrow extract
Filtered extract
Filtered extract
Filtered extract
Filtered extract
Transferring in-furrow extract
Transferring in-furrow extract
Fertilizing small plots
Fertilizing small plots
Planting On-farm Trial plot
Planting On-farm Trial plot
Planting Small Plots
Planting Small Plots

23 On-farm Trial Protocol

Research results and discussion:

SARE - Year 1 Johnson-Su Bioreactor in Wheat, Soybeans, and Sunflower Preliminary Results2023 OFR ReportReport Table 1

Report Table 2

Report Table 3

In this first season, differences in N rate treatments were too great to measure any potential biological response. A better choice of treatments would have been similar to the treatments used in the Pivot Bio wheat inoculation trial (see previous section).

There was a small but significant yield increase with the in-furrow application in sunflowers, which aligns with anecdotal evidence that extract efficacy increases in the order of foliar application < seed treatment < in-furrow application.

SARE - Year 1 Johnson-Su Bioreactor in Wheat, Soybeans, and Sunflower Preliminary Results

Participation Summary
2 Farmers participating in research

Educational & Outreach Activities

2 Consultations
1 Curricula, factsheets or educational tools
1 On-farm demonstrations
1 Tours
8 Webinars / talks / presentations

Participation Summary:

332 Farmers participated
Education/outreach description:

7-18-23 - Presented to approximately 20 farmers, industry reps, and researchers during a field tour of the small plot research portion of this project hosted for the MN Wheat Research and Promotion Council's Wheat Research Committee. 

12-13-23 - Presented on-farm yield, tissue test, and soil test results to approximately 75 growers and industry reps during the 11th annual On-farm Research Summit at the Prairie Grains Conference in Grand Forks, ND. The participating farmers were also in attendance to answer questions as needed. The recording video recording is posted on MN Wheat's YouTube channel at https://www.youtube.com/watch?v=XPOS1E4vO2Q&list=PLD9ujiJyhaYcd1ur6bo2wA5UQQJKpsMA2&index=2. 

12-13-23 - Printed copies of our On-farm Research Report containing our preliminary 2023 trial results were passed out to each grower at the On-farm Research Summit. 

1-9-24 - 1-12-24 Presented a condensed version of the on-farm trial results to approximately 237 growers and industry reps during MN Wheat's Small Grains Updates Meetings, a series of grower meetings in NW MN held in Dilworth, Crookston, Ada, Hallock, Roseau, and St. Hilaire, MN, over the course of 4 days. The printed on-farm research reports containing the project results were also passed out to each attendee. 

Learning Outcomes

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

Project Outcomes

Project outcomes:

This project has helped the local farmer cooperators to apply and test compost/vermicast extract at field scale on their own farms, and has allowed us to share the story of the process and how to do it with other growers in the area who have been interested and asked questions. The results from this year have also shown that there is alot more to be figured out with methods, application rates, and crop fertility, and that the extract is not a silver bullet to reducing fertilizer requirements, but will take some further finessing to figure out when, where, and how the applications will benefit crop production and soil health. 

Success stories:

Beef and Wheat/Soybean/Corn/Sunflower/Pea farmer cooperator, Red Lake Falls, MN - [We] had made a bioreactor in a previous year, but didn't really know how to, or dedicate the resources to applying it in order to test it. We also didn't test the biology present in the bioreactor we had, so didn't have confidence anything was there, or if there was any bad biology in the compost. Making the compost was labor-intensive, but determining how to use and apply the compost extract was a skill that was daunting for us without the help this grant provided. 


Coordinator Recommendations - Last year we determined the treatments we used in the on-farm trials led to ambiguous results, we were too aggressive with the reduced fertilizer rates and failed to include a reduced rate control with no extract. In the 2024 season, we plan to switch to the following treatments:

  1. 120 lbs N, no extract
  2. 60 lbs N + extract
  3. 60 lbs N, no extract
  4. Optional – 120 lbs N + extract


Farmer cooperator recommendations/comments -

  • There is a need for good screens and nozzles.
  • We are able to put down a lot more compost product in furrow than seed treatment.
  • Seeing the impact the worms made in the bioreactors has been impressive. 

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.