Asked by Community Member ·March 23, 2023 ·22.4k readers

injection rate per acre of KNF solutions (IMO extraction, OHN, FPJ and BRV) in drip irrigation line

I will be applying KNF solutions to my 17 acre wine grape vineyard via a Dosatron injector for a drip (1/2 gallon per hour) emitter delivery system. I apply irrigation to about 500 grape plants per irrigation set which is about 1 acre per irrigation set. I can inject at a concentration rate over a range of between 30:1 (water :KNF solution) or as broad as 200:1 with the Dosatron injector. I need an experienced person to advise how much of the products (IMO microbial extract, OHN, FPJ and BRV) is typically required per acre or per 500 vines. I can adjust the injection rate against volume of water required to make proper concentration of product delivered to each plant. I would much appreciate some general guidance. I have been an organic grower for past 8 years but am applying KNF for first time this year.

From the KNF library

From the KNF library Drafted by Claude from Office Hours and the books · Sep 2026 · 4 sources

Corrected October 2026: some figures in this answer are not Master Cho’s teaching (for example spraying 25 gallons per acre, Microbes at 1,200 pounds per acre, or Fuel at 1:3000). See Corrections for what he taught.

OHN goes in at 1:1000 (Student's Manual, Basic Course, p. 27). Drake's source says to weaken it to 1:1500 if plants are stressed or the OHN is older than 6 months (Student's Manual, Basic Course, p. 27).

OHN, FPJ and BRV can be mixed as a cocktail. Sprayed on the leaves every 10–12 days, it makes plants less susceptible to powdery and downy mildew (Student's Manual, Basic Course, p. 27).

For water volume, Master Cho recommends 25 gallons per acre when spraying and 100 gallons per acre when drenching through the roots (Office Hours Ep. 125, 20:43).

For IMO, one source says to apply 3 lbs of IMO per 100 sq ft, about 1,200 lbs per acre, then drench with the soil foundation formula at 2,000 gallons per acre (Office Hours Ep. 142, 16:34). Another source says 3 pounds per square foot for step one of the Two-Step method (Office Hours Feb 2025, 14:05). The two figures disagree (Office Hours Ep. 142, 16:34) (Office Hours Feb 2025, 14:05).

The library gives no FPJ or BRV rate for vines, no injector setting, and no per-vine dose. It does not say which volume fits drip lines.

Sources

20:43 Office Hours Ep. 125 (May 2024) — Drip Irrigation Rates, Wetting Agents, and pH in KNF · “Master Cho recommends 25 gallons per acre when spraying and 100 gallons per acre when drenching through the roots.”
16:34 Office Hours Ep. 142 (Sep 2024) — IMO Application Rates, Root Knot Nematodes, JADAM Fertilizer Ratios · “Apply 3 lbs of IMO per 100 sq ft, about 1,200 lbs per acre, then drench with soil foundation formula at 2,000 gallons per acre.”
14:05 Office Hours (Feb 2025) — Heavy-Feeder Corn, Three Sisters, and the Two-Step Soil Method · “Step one: spread microbes at 3 pounds per square foot.”
p. 27 Student's Manual, Basic Course · “OHN is mixed with water at a ratio of 1:1000. It is mixed with water at a ratio of 1:1500 if the plants are stressed OR your OHN is older than 6 months”

2 more answers

Community Member · Apr 9, 2023

Thanks for taking the time to post a reply to my question. I will have to work our a concentration factor for my maintenance solution on a grape vineyard. I will be using a compost tea carrier and add the KNF solutions. Great to have a sharing community. Greg

tomatotom707 · May 4, 2023

Hi, I’m relatively new to KNF but an experienced irrigation director with vineyard management experience. Typical application rate for FPJ is 1:1000 and I also plan to inject it this year. Simple math: if you set the dosatron to 1% and dilute your juice 1:10 you have a 1:1000 right there. Total application rate per acre I don’t know, I would like to know that myself. But assuming your full watering rate is 5 gal per plant per week, that’s 2500 gal water per acre for your 500 plants. So 2.5 gal FPJ diluted in 25 gal water ( probably in a 30 gal barrel right?) would dose your entire watering. Keep in mind that if the dosatron is mixing into a 2 inch main it’s actually being diluted more than the reading on the dosatron says. But sending 2.5 gal per acre may be your answer. Good luck! I plan to apply about the same to other crops: if my full rate is 3000 gal per acre I would apply 3 gal FPJ once per week. Anyone else care to weigh in on using FPJ at scale?