Fertigation: Fertilizing & Irrigation Made Easy

Early to bed, early to rise, work like hell, fertilize.” -Emily Whaley

Whether we garden for fun or profit, there’s plenty of effort involved. We work the soil, sow seeds, set in transplants, and we install drip irrigation to water efficiently. Fertilizing gives our efforts an extra boost by notably improving plant vigor and production. For backyard gardeners, that means the best tomatoes and most prolific fruits and flowers. In the case of commercial growing, it means higher crop yields that are critical to financial success.

Why use a fertilizer injector?

Fertilizing and watering are two of the most important tasks in a growing operation, and they are two of the most time consuming tasks. Fertilizer injectors are a fast and accurate way to feed plants in a drip irrigation system. Because these injectors deliver liquid nutrients only where plants need it most – directly to the roots – fertilizer injectors are also the most efficient way to nourish plants.

When a drip irrigation system is in place, water soluble fertilizer can be directly dispersed through the system by way of a fertilizer injector. This is called fertigation.  Incorporating a fertilizer injector into a drip irrigation system allows you to automate fertilizing as well as watering.

Note: You will need to use a water soluble fertilizer and you will want the filter below the fertilizing unit.  Both of these precautions will help minimize the risk of clogging drip emitters.  In addition, you will always want to place a backflow preventer up stream of the unit to prevent fertilizer from entering into your water source.

How they work

Injectors remove a small amount of concentrated fertilizer from a stock tank and inject it into a water line. There are two basic types of fertilizer injectors. One uses water pressure and the other a pump to move fertilizer solution from the stock tank into the system. These systems inject a precise amount of fertilizer solution to create a particular ratio of solution to water.

Add-it and Ez-Flo injectors use water pressure to move fertilizer from the stock tank into the water line.  Whereas, MixRite Injectors use a pump to move the fertilizer.

What the solution ratio means

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. We offer a wide range of stock tank sizes, ranging from as small as 1 pint to as large as 10 gallons. Often ratios are expressed as percent. For example, a 1:100 ratio equals a 1 percent solution.

Fertilizer injectors can come with fixed or variable solution ratios, and that choice will be determined by your project needs.

Which fertilizer injector is right for my project?

Units come in two categories, Constant pressure and non-constant pressure.  The non- constant pressure units are usually designed to connect to a hose bib and are normally a great fit for the backyard gardener.  The downside to the non-constant pressure tanks is that you will normally connect one unit to each zone.  So if you have 3 zones you would need 3 units.  You can always move one unit from zone to zone as needed but if you have the system automated it can take away from some of automation as you have to remember to move the unit.

The Constant Pressure units are spliced directly into the main water source and are usually much larger tanks. These tanks can feed multiple zones but are generally much more expensive and require some minor plumbing to install.

When units are built to withstand constant pressure, that means they can be installed before the valves and timer (but after a backflow preventer). It will be clearly stated in the product description if a unit is built for constant pressure or not.

Once you make the choice of which type of unit you want, you will next want look at size.  For example, lets look at the ¾ gallon EZFlo unit with adjustable feed ratio of 1:100 to 1:1000.

At 1:100 the unit will empty of fertilizer after 75 gallons of water have passed through the unit.

At 1:1000  the unit will empty of fertilizer after 750 gallons of water have passed through the unit.   

So as you can see, getting the right size and feed ratio is important.

Once you have narrowed the choices down you will want to review the specifications of each unit that you are interested in.  In order to match the following to your system and fertilizer.

  • Feed Ratios
  • Minimum flow Requirements
  • Minimum Pressures Requirements

Backyard Garden Models

Starting with the backyard gardener’s needs, generally a smaller unit at an economical price will work perfectly. The EZ-Flo Fertilizing System accommodates water pressure as low as 5 psi and up to 80 psi. The hose bib EZ-Flo injectors have an adjustable ratio that makes them flexible and easy to use. Add the desired amount of a concentrated, water soluble fertilizer and set the adjustment valve. Hose end units include a hose bib adapter which connects directly to a standard 3/4" GHT (Garden Hose Thread), hose end or faucet. This is the most economical EZ-Flo unit, but it’s not built for constant pressure, so when used with a drip system the tank must be installed after any valve system or timer.

The Add-It Proportioning Fertilizer Injectors are made out of heavy duty PVC. The  1.5 Quart can be installed before a manifold of valves under full line constant pressure up to 125 psi, and both sizes can be installed after a single control valve. The Add-It needs a minimum water pressure of 10 psi.  

Commercial models

MixRite fertilizer injectors are some of the most accurate units on the market in terms of portion control. They are ideally suited for inline injection and are often used for farms, greenhouses or nurseries. They also have other farm uses such as portioning vitamins for animals or dispersing cleaning fluids. The MixRite TF series models have adjustable injection rates and a variety of flow ranges. They are designed to be used with a master valve in large systems.

The EZ Flo mainline dispensing system is a commercial unit that can be used by those needing a constant pressure system. It connects directly to the irrigation piping after the backflow prevention device. This product is designed to feed both sprinkler and drip irrigation zones for commercial, municipal, golf course, grower and residential applications.

Drip Depot carries a wide variety of fertilizer injectors in order to fit a multitude of agricultural needs and budgets. Find out more about them on our website.