Research for the Validation of Regenerative Citrus

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2023: $14,843.00
Projected End Date: 03/31/2025
Grant Recipient: Squeeze Citrus LLC
Region: Southern
State: Georgia
Principal Investigator:
Herb Young
Squeeze Citrus LLC


  • Fruits: citrus


  • Soil Management: composting, soil quality/health

    Proposal summary:

    SARE Sales Markets Net$
    Finding locally sourced compost that is indigenous to the area and would adapt to a citrus ecosystem would have several significant economic implications to Squeeze Citrus LLC. The immediate economic impact would be on operational expenses for the grove. 
    1. reduction but not complete elimination of organic fertility expenses ($720 per acre per year).

    2. A fully integrated microbial ecosystem in the soil is documented to result in dramatic increases in BRIX levels in plants (dissolved solids) which is an indication of plant health. Higher BRIX will give plants a greater degree of freeze protection which is a major limiting factor for Citrus in Georgia.

    3. An increase in BRIX has also been documented to reduce insect feeding due to a lack of sophistication in their digestive system. Currently the major limiting insect pest in Georgia is the citrus leaf miner. Dr. Tom Dykstra has documented that leaf miners will cease feeding at BRIX levels above 12. The cost of leaf miner control is $80 per year/A.

    The more significant economic impact of an indigenous effective microbial ecosystem would be nutrient dense fruit and the value it would bring in the marketplace. I have estimated the incremental increases in the value of fruit per pound based on current knowledge of the markets. Market values would increase significantly at each step from wholesale to organic to nutrient dense to premium restaurants to community supported agriculture (subscription boxes) to food as medicine. Based on University of Florida yield estimates for Citrus in the south east the following net profit is estimated for Squeeze Citrus LLC.  A full spreadsheet with all the calculations is attached. The net profit is calculated from gross value per pound minus actual harvest cost per pound minus yearly maintenance cost (calculated from actual 2022 monthly expenses).



       estimated  2021 2022 2023 2024 2025
    MARKET $/lb fruit   UF Yield Estimates: per tree >> 20 lb/tree 60 lb/tree 110 lb/tree
    Wholesale  $0.60  $(31,704)  $(34,874)  $(25,383)  $(3,260)  $24,968
    Organic  $1.00  $(31,704)  $(34,874)  $(16,730)  $22,698  $72,558
    Premium Restaurant  $1.20  $(31,704)  $(34,874)  $(12,403)  $35,677  $96,353
    CSA **  $1.50  $(31,704)  $(34,874)  $(5,914)  $55,146  $132,046
    Food as Medicine  $2.00  $(31,704)  $(34,874)  $4,902  $87,594  $191,534

    ** CSA is Consumer-Supported Agriculture (subscription boxes).  There are 8,000 CSAs in America.  They are almost entirely organic vegetables which are primarily available in the spring, summer and declining in the fall.  Citrus harvest is November through April and would fit perfectly as the source of produce for CSA customers who continue their subscriptions year round.  Example:  Willow Haven Farm outside of Philadelphia has 250 boxes/week subscriptions in the summer months which declines to 100 boxes/week in the winter when they are forced to source produce from outside.  

    The chart assumes that the full crop will go to a single outlet.  The most premium outlets may have smaller portions of the harvest with remaining poundage going to other markets, therefore the final net value will be a mix of the above estimates. 

    Project objectives from proposal:

    Herb Young has spent 25 years in field testing and research positions in the Ag Chem industry. This experience included large scale for field demonstration plots, large scale replicated trials (2 to 10 acres), and small scale replicated plots on rented grower fields and on corporate research farms. He has a masters degree in plant pathology from Clemson University that included two years of replicated field trial experience in soybean diseases. His direct fruit tree experience during his career has included Citrus in Florida, stone fruits and apples in the northeast, and working with university trials in the Pacific Northwest and nut crops in California. 

    At Squeeze Citrus LLC there are currently five replicated field trials dealing with regenerative practices. They include: 

    1. Regenerative versus conventional growing practices.
    2. Evaluation of algae, Chlorella vulgaris, application techniques as a plant and soil stimulant.
    3. Evaluation of Algae as a stimulant on cover crop seeds.
    4. Evaluation of mowing practices for cover crop management.
    5. Evaluation of the fungal endophyte Beauvaria bassiana for the control of citrus leaf miner.

    This proposal for the search for viable indigenous microbe sources through compost would include the following replicated trials:

    1. Continuation of the already established regenerative versus conventional trial into its third and fourth year (the trial was set to expire at the end of 2022 and results are yet inconclusive). Measurements include: Twice per year trunk diameter measurements for each tree (15 trees/plot, three replications, three treatments), leaf flush ratings per tree three times per year, and soil DNA analysis by Biome Makers in the spring and fall each year.

    2. Identifying a living compost source which has microbes that are indigenous or will adapt to citrus and remain viable from year to year.  Current sources are:  on-farm compost from a static pile made of power-line trimmings, a local commercial compost from wood-chips + cow manure + biochar, and potentially a vermicompost from a local bait shop (limited quantity).  This trial would be a replicated trial (minimum 5 trees/plot) of evaluation of all compost sources vs. an untreated.  The same evaluations described for trial #1 above would be used.

    3. Compost tea would be the quickest (24-48 hour) and most economical way to ramp up microbe populations and apply to trees and soil.  Each of the compost sources will be evaluated in a compost tea as the microbe (bacteria + fungi + protozoa) source.  Detailed records of each recipe will be kept and trees will be evaluated for one month following each application.  Leaf flush and general tree vigor will be the primary evaluations.  Two application methods will be evaluated:  air blast sprayer foliar application (some material will reach the orchard floor and impact microbial population) and irrigation injection through microjet placed at each tree.  Both types of application method will be used for the entire grove with replications being tree rows as untreated. The compost tea brewer owned by Squeeze Citrus is a 275 gallon tote modified with a high-volume air bubbling system.  Each "batch" is 250 gallons by necessity and should be sufficient to treat the 5 acre grove.  The compost will be evaluated microscopically for life (activity) prior to brewing and the compost tea will be evaluated for life after brewing.  Quantification may be possible (i.e. bacterial counts).

    A critical measurement under girding all of these trials will be the Haney Soil Health Analysis.  It includes:  Soil Respiration which is a measure of biological activity, Organic Carbon which is a measure of available microbial food, and % Organic Matter as well as multiple other measurements including fertility.  An additional test will need to be found to give a bacterial:fungal ratio in order to plot the rise of fungal populations which are critical to sustain tree crops.  The goal of a self-perpetuating system is a fungal dominated soil, particularly mycorrhizal fungi which are absent in the soils of Squeeze Citrus.


    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.