Fertigation · injectors · ratios · not a kit

How to fertigate a high tunnel: injectors, ratios, backflow, and filters on drip (sourced)

Growers search high tunnel fertigation, fertilizer injector, Dosatron, Mazzei venturi, Hozon siphon, and injection ratio when the drip header is already in the house. This page is the injector sibling — how a water-powered proportioner differs from a venturi or a 1:16 siphon, what 1:100 actually means, how to pick by zone flow, and why backflow and a filter after injection sit on the same header. Tubing, emitters, and the 3/4-inch regulator stay on high-tunnel drip irrigation. Salt after years of drip-only water stays on high-tunnel soil salinity. Tomato season stays on high-tunnel tomatoes. Winter lettuce calendars stay on high-tunnel winter lettuce. It is not a commercially manufactured high-tunnel kit and not a USDA payment schedule.

Quotes copied 28 October 2026, about 04:00 UTC from Alabama Extension ANR-1433 (revised February 2022), UGA B1237 (full review 9 April 2024), UMass fertilizer-injector fact sheet, Maryland FS-1121 (page updated 10 April 2026), UMN irrigation set-ups, Missouri IPM (22 February 2023), plus the High Tunnel System Initiative FAQ and the Pennsylvania seasonal high tunnel page. Featured Amazon prices copied the same night. A missing featured price stays an em dash. Ratings are not copied. Seller GPM and PSI stay labeled seller. This page does not invent a USDA dollar, a zone GPM table, or a ppm recipe.

Kit index: commercially manufactured kits. Replacement-parts directory: high-tunnel replacement parts. Drip tubing / emitters / regulator: drip irrigation. Salts after fertigation years: soil salinity. Tomatoes: high-tunnel tomatoes. Winter lettuce: winter lettuce. County inspection: EQIP checklist. What the program will not pay for: EQIP will not pay for. Affiliate method: about / disclosure.

The house cuts off the rain. The injector feeds the tape.

ACES wrote the high-tunnel sentence. UMN wrote that soluble feed through drip is common in these houses. The tape, the 2 GPH emitters, and the 25 PSI regulator already live on the drip-parts page.

Fertigation is the process of directly applying fertilizer to a crop through the irrigation system. High tunnel production systems, much like plastic mulch, prohibit the natural delivery of water as rainfall. The artificial environment requires the producer to supply all the crop’s water needs. Drip irrigation has become the standard system for applying water to high-value crops typically grown in high tunnels.

Source: Alabama Extension ANR-1433 — High Tunnel Irrigation and Fertigation (revised February 2022; opened 28 October 2026). UMN: Many growers apply soluble fertilizers through their irrigation, especially in high tunnels. These injector systems are common in high tunnels, especially among growers who use fertigation (fertilizing with water-soluble fertilizers through irrigation water).

Three injector families. Do not swap them.

ACES named three types. UGA and UMD split venturi from positive displacement. UMN put Dosatron and MixRite on the precise side and Venturi on the trial-and-error side. Featured tonight: a Dosatron D14MZ2, a MixRite 4% unit, a Mazzei 584-PP body, and a Hozon 1:16 siphon.

Three types of injectors may be used: pressure differential or venturi types, water-powered piston or diaphragm pumps, and externally powered positive displacement pumps.

Source: Alabama Extension ANR-1433 — High Tunnel Irrigation and Fertigation (revised February 2022; opened 28 October 2026). UGA venturi: Venturi-type injectors, such as Hozon and Syphonex use a pressure difference between the water line and the stock tank to draw a concentrated solution into a faucet connect valve and mix it with water in the hose. These inexpensive injectors can be easily attached to any faucet but do not allow precise control over concentration. Because of water pressure fluctuations variable amount(s) of chemical may be injected into the hose. In addition, the injection ratios are low (typically 1:16) and therefore require a large stock tank, thus limiting the use of Venturi-type injectors to small growing areas. UGA / UMD Hozon floor: It needs a minimum 35 psi (pounds per square inch) water pressure for proper operation. A Hozon® venturi injector delivers a soluble concentrate at 1:16 dilution ratio at a minimum of 35 psi. Hose length: The Hozon should not be more than 50 ft from the nozzle end to work properly.

Positive displacement injectors, such as Dosatron, DosMatic, Anderson, Smith, and Gewa products provide consistent injection ratios for the designed flow rates over wide variations in water pressure. These injectors operate without electricity, using water pressure as the power source. They are installed directly in the water supply line. Water flow activates the injector, which takes up the required percentage of concentrate directly from a container with stock solution.

Source: UGA Extension B1237 — Pennisi / Kessler, Fertilizer Injectors: Selection, Maintenance and Calibration (full review 9 April 2024; opened 28 October 2026). UMN: Volumetric proportioning injectors (Dosatron, MixRite) are much more expensive than Venturi-style injectors, but they are also more precise. These injectors use hydraulic motors to pull liquid (fertilizer or acid solution) from a container or tank into the waterline. This means they are powered by the water flowing through them, and they do not require a power source. They maintain a consistent concentration, even if the flow rate or pressure of the water main line changes. UMass: Some injectors (Hozon,) have a fixed (nonadjustable) injector ratio whereas other injectors (Dosatron, Anderson, Dosmatic) have adjustable ratios.

1:100 is a dilution. It is not 100 ppm.

UMass printed the sentence growers get wrong. Mix the stock to the bag for that ratio. UGA prefers greenhouse ratios of 1:200 or richer so the fertilizer actually dissolves.

It is important to remember that an injector does not deliver a fixed ppm N. You need to determine the amount of fertilizer to dissolve per gallon of water (stock solution) to make the appropriate concentrate for a specific injector setting. An injector setting of 1:100 does not mean that the injector is delivering 100 parts per million (ppm) nitrogen. A 1:100 injector will deliver 100 gallons of dilute fertilizer solution for each gallon of concentrated stock solution. A 1:200 injector will deliver 200 gallons of dilute fertilizer for each gallon of concentrated stock solution (or 100 gallons of dilute solution per ½ gallon of stock). A 1 percent setting is the same as a 1:100 ratio, a 2 percent setting is the same as a 1:50 ratio and a 0.5 percent setting is the same as a 1:200 ratio.

Source: UMass Amherst — Tina Smith, Fertilizer Injectors for Greenhouses (3/09, reviewed 8/15; opened 28 October 2026). UGA: Injectors take a small portion of concentrated fertilizer solution from a stock tank and inject it into the water line. For every part of stock solution, there are x parts of water, where “x” is determined by the injector ratio. For example, with a 1:100 ratio 1 part of stock solution is mixed with 99 parts of water, for a total of 100 parts of final solution. Often ratios are expressed as percent. For example, a 1:100 ratio equals a 1 percent solution. UMD 1:50: For instance, at an injection rate of 1:50 the injector will pump 1 part of concentrated material into 49 parts water equaling a total of 50 parts of final solution. Missouri 1:100 volume check: 1:100 — 1.3 ounces of stock per gallon; 6.5 ounces of stock per 5 gallons. UGA solubility: With ratios more than 1:200, incomplete dissolution of fertilizer may occur, as maximum solubility is exceeded. For greenhouse operations, injection ratios of 1:200 or lower are recommended.

Pick the injector from the zone, not the catalog photo.

ACES tied gallons per minute to house size, tape, and how many zones run at once. UGA said the limit is the injector's min and max flow. UMN said pick a Venturi model from that flow. Measure the zone. Do not invent a 20×40 GPM table.

The amount of water needed per minute will depend on the size of the high tunnel being used, the type of tubing (drip tube, emitter spacing, flow rate) used, and the number of irrigation zones operating at the same time.

Source: Alabama Extension ANR-1433 — High Tunnel Irrigation and Fertigation (revised February 2022; opened 28 October 2026). UGA: The limiting factor in these injectors, in most cases, is the minimum and maximum water flow rate permissible. Flow rates fall into three categories: low (0.05 – 12 gpm), medium (12 – 40 gpm) or high (over 40 gpm). UGA Dosatron model range: Maximum flow rates for Dosatron injectors range from 7 gpm to 264 gpm for various models, with ratios ranging from 1:50 to 1:500 for smaller flow rates, from 1:50 to 1:500 or 1:1000 for larger flow rates. That range is not tonight's 14 GPM Amazon SKU. UMN Venturi: There are many models of Venturi-style injectors; choose the correct model based on the flow rate of your irrigation system. Stock tank size is UGA's 5-to-2,000-gallon sentence — no featured tank tonight.

Keep in mind the small portion of an acre available inside a high tunnel demands smaller amounts of fertilizer. Fertigation amounts will be a fraction (literally) of most of the recommendations found in many publications and labels for crop production. If a high tunnel has 8 rows that are each 90 feet long, then there is a total of 720 row feet in that high tunnel.

Source: Alabama Extension ANR-1433 — High Tunnel Irrigation and Fertigation (revised February 2022; opened 28 October 2026). Their 8 × 90-foot / 720 row-foot calcium-nitrate walk-through is an Alabama example, not a Tunnel Spec recipe. Preplant N: Before planting 20 percent to 40 percent of the required nitrogen may be applied and incorporated. As soon as the crop is planted, the irrigation system should be available to water plants and supply additional nitrogen or other necessary nutrients. An injector will be used to supply most of the post-planting nutrients.

Backflow on the source. Filter after you inject.

ACES put a preventer between the water and the injector and put injection upstream of the drip filters. UMD also wants grit out before a piston pump. Missouri wants a bypass so you can flush with clear water. Header regulator and 1/2-inch mainline stay on drip irrigation.

A backflow preventer should always be installed between the water source and fertilizer injector to prevent possible contamination. A functioning backflow preventer is needed between the water source and injection. Fertilizers should not be combined with pesticides or chlorine. Injection site must be upstream of the filters. Irrigation system must be at full operating pressure before injection begins.

Source: Alabama Extension ANR-1433 — High Tunnel Irrigation and Fertigation (revised February 2022; opened 28 October 2026). UMN: For growers who inject fertilizer, acids, or any other chemicals into their irrigation water, backflow prevention is required to prevent contaminating the water source. Any fertilizer injector should be paired with a backflow prevention device to prevent fertilizer or other chemicals from entering the water supply.

A check valve or back-flow preventer is placed in line between the filter and the pump. This is a one-way valve. It only allows water to move in one direction (an arrow on the valve should point to the pump) and prevents any fertilizer water from reversing direction back into your water source. An external filter is necessary to filter any abrasive particles in the water before entering your pump.

Source: University of Maryland Extension FS-1121 — Schuster / Ristvey, Care and Calibration of Injector Pumps (January 2020; page updated 10 April 2026; opened 28 October 2026). Missouri: Install the injection system off the mainline in a water bypass. This set up allows for clean water to flow to flush the irrigation lines or to water the crops when no injection is needed. A check valve (backflow prevention) is required to prevent contamination of the water source! Use screen or disk filters and establish a set schedule to clean the filters. The cleaning frequency will depend on the water quality. The pressure regulator is needed if the pressure in the main line is higher than the recommended operating pressure of the injector. Also, remember that emitters in drip irrigation system have a set range of operating pressures. University of Missouri IPM — Juan Cabrera-Garcia, Injector Installation and Performance Check (22 February 2023; opened 28 October 2026). UGA grit before the proportioner: Particulate matter (solids such as grit or sand) in your water supply act as abrasives and will wear away the water measuring mechanism. If you have problems with solids, install a filter upstream of the injector and place pressure gauges before and after the filter.

Sourced Amazon fertigation gear

Titles and featured one-time prices were copied from live amazon.com product pages 28 October 2026, about 04:00 UTC. No featured stock tank tonight. Skipped: B07HJFM6TC — Dosatron D14MZ2VFII alternate URL: live PDP, no featured one-time offer (New-from $559.99 / other $565.95).; B00B8CAVIK — EZ-FLO 5-gallon main-line dispenser: Amazon interstitial / no featured PDP tonight.; B00PM8Y79K — Watts Series 8 hose-bib vacuum breaker 792085: currently unavailable / no featured price.; B09Q864M1T — Savvyject Mazzei loop kit: live $92.00, skipped so the Mazzei 584-PP body is the venturi row.

EQIP pays for the structure, not the injector

Proportioners, venturi bodies, siphons, stock tanks, backflow devices, and extra filters sit outside the High Tunnel System Initiative payment. A nearby water source is a siting rule. Confirm with your NRCS district conservationist. Tunnel Spec does not invent a dollar.

Under the High Tunnel System Initiative, financial assistance is provided only for the structure itself. Electricity, venting systems, lighting, etc. can be installed providing the additions meets manufacturer’s designs and specifications. However, the grower is responsible for those costs.

Source: USDA NRCS High Tunnel System Initiative FAQ (Updated November 2024; Oregon-branded). That PDF names electricity, venting, and lighting as grower cost. It is silent on an injector dollar.

High tunnels must be placed near a viable source for irrigation. NRCS requires proof that legal access to water exists, regardless of how irrigation is obtained, before a high tunnel system can be designed for implementation. Oregon NRCS has a worksheet that is required to be signed by a verified authority confirming legal access to water. Some farms may be exempt.

Source: USDA NRCS High Tunnel System Initiative FAQ (Updated November 2024; Oregon-branded). Legal access to water is not a Dosatron reimbursement. The Oregon worksheet mention is the FAQ's own wording.

Producers can install heating, ventilation, or electrical systems at their own expense.

Source: USDA NRCS Pennsylvania — Seasonal High Tunnel System for Crops. One state office page. More exclusions: what EQIP will not pay for.

Rules vary; call your county NRCS office.

FAQ

What is fertigation in a high tunnel?

ACES ANR-1433: fertigation is applying fertilizer through the irrigation system. A high tunnel, like plastic mulch, cuts off rainfall, so the grower supplies all the water; drip is the standard for high-value tunnel crops. An injector moves a concentrated stock into that drip line. UMN: soluble fertilizers through irrigation are common in high tunnels. Tubing, emitters, and the header regulator stay on the drip-parts page. EQIP pays for the structure, not the injector.

Dosatron / MixRite vs Mazzei venturi vs a Hozon siphon — which injector?

UGA and UMD split the hardware: venturi (Hozon, Mazzei) uses a pressure drop and changes ratio when pressure or flow changes; Hozon is typically 1:16, needs about 35 PSI, and wants a large stock tank. Positive-displacement / volumetric proportioners (Dosatron, MixRite, Anderson, Smith) hold a set ratio across a designed flow band and run on water pressure without electricity (UMN, UGA). UMass: Hozon is a fixed ratio; Dosatron / Anderson / Dosmatic are adjustable. ACES names three families: pressure-differential / venturi, water-powered piston or diaphragm, and externally powered pumps. Do not treat a 1:16 siphon as a 1:100 Dosatron.

What does 1:100 or 1% actually mean?

UMass: a 1:100 injector delivers 100 gallons of dilute solution per gallon of stock; 1:200 delivers 200 gallons per gallon of stock. A 1% setting is 1:100, 2% is 1:50, 0.5% is 1:200. A 1:100 setting is not 100 ppm nitrogen — mix the stock to the fertilizer label for that ratio. UGA: 1:100 is 1 part stock + 99 parts water. UMD: 1:50 is 1 part concentrate + 49 parts water. Missouri: at 1:100, 1.3 ounces of stock per gallon (6.5 ounces per 5 gallons). UGA cautions that ratios leaner than 1:200 can fail to dissolve fertilizer; greenhouse operations are often 1:200 or richer.

How do you pick an injector from drip-zone flow?

ACES: gallons per minute depend on tunnel size, tape / emitter spacing and flow, and how many zones run at once. UGA: the limit on a proportioner is its min/max flow; they group flow as low 0.05–12 gpm, medium 12–40 gpm, high over 40 gpm, and print Dosatron model maxima from 7 to 264 gpm. Featured tonight: Dosatron D14MZ2VFII seller 0.05–14 GPM; MixRite IMR4SO seller 5.4–660 GPH. UMN: choose a Venturi model from the irrigation system’s flow rate. Measure the zone. Do not invent a 20×40 or 30×96 GPM table, and do not average UGA’s model range with one Amazon SKU.

Where do backflow prevention and the filter go?

ACES: a functioning backflow preventer between the water source and injection; inject upstream of the filters; bring the system to full operating pressure before you inject; do not mix fertilizer with pesticides or chlorine. UMN: backflow is required if you inject fertilizer or acid. UMD: grit filter before a piston pump; check valve between that filter and the pump, arrow toward the pump. Missouri: bypass off the main so you can flush with clean water; screen or disk filters on a schedule; a regulator if line pressure is above the injector. Two filters are two jobs — protect the pump, then catch undissolved stock before the tape. Hose-bib vacuum breakers are not a local-code letter.

Does EQIP / NRCS practice 325 pay for a fertilizer injector?

Tunnel Spec does not invent eligibility or dollars. The High Tunnel System Initiative FAQ (Updated November 2024) says financial assistance is provided only for the structure itself, and that electricity, venting, lighting, etc. are grower cost even when they meet manufacturer designs. The same FAQ requires a viable irrigation source and proof of legal access to water — that is a siting rule, not an injector payment. The Pennsylvania seasonal high tunnel page says producers can install heating, ventilation, or electrical systems at their own expense. Injectors, stock tanks, backflow devices, and extra filters sit with those grower costs. Confirm with your NRCS district conservationist. See what EQIP will not pay for.

Rules vary; call your county NRCS office. Tunnel Spec does not determine eligibility, payment rates, or inspection outcomes. Not a ppm table and not a USDA dollar. As an Amazon Associate, we earn from qualifying purchases.