Fertilizer Injectors Have Advantages and Disadvantages

Q. I know of fertilizer systems which friends have linked to their home yard watering systems. These can be adjusted as to the quantity of fertilizer added to the water. However, it seems this might be quite a bit of fertilizer applied to the plants. Yet, a neighbor is very enthusiastic about the benefits. Can you advise me on this subject?

Simple fertilizer injector using a stock tank of a fertilizer dissolved in water. Here we are preparing the stock solution to be injected into the irrigation line using the Venturi effect. In Kosovo.

A. These fertilizer systems have different methods of injecting fertilizer into the water. They range in different prices based upon how precise they can deliver fertilizer. Collectively we call them fertilizer injectors. They can be adjusted so they deliver a very tiny amount of fertilizer or deliver a lot of fertilizer at one time and then turned off until needed again.

The fertilizer was injected into the irrigation line and was applied with overhead drip irrigation using micro sprays. This is seedling production in a greenhouse in Kosovo. Benches were created using bales of straw.

Background. Fertilizer injectors were designed primarily for agriculture and commercial horticulture use where one type of plant is grown or plants grown with similar water and fertilizer requirements. Their primary purpose was to save the cost in applying fertilizer.

Several types of injectors are available for home landscapes in a range of prices. The primary difference in these injectors is their level of precision. Most inexpensive homeowner fertilizer injectors operate on the "venturi effect". The venturi effect pulls a concentrated fertilizer solution from a bucket or small tank into a stream of water. This stream of water might be in a hose or an irrigation line. The principle of the venturi effect  is used in some automated pool cleaners, wine aerators, recoilless rifles and in the pressure regulator for scuba gear.

You can watch how the Venturi effect works in irrigation lines in this video from Jain Irrigation
https://www.youtube.com/watch?v=tGlZLwvI6PY

The venturi effect causes concentrated fertilizer solution to mix into the stream of irrigation water. You can operate your injector to apply fertilizer continuously or periodically on a fixed schedule; once a month; once every three months, spring and summer, etc. If you put fertilizer in the injector, it will fertilize. If you don't, it won't.

Advantages and Disadvantages. The primary advantage to the homeowner is less labor which saves time. Some may argue it also saves the homeowner money and the landscape looks better. Both are arguable but I don’t think anyone can argue it is not a timesaver. I will go into more detail on my blog.

The primary disadvantage for homeowners is that all plants which receive water at the same time also receive the same kind of fertilizer. When fertilizing plants by hand, you have the option of giving them different types of fertilizers, not all the same kind.

Plants which receive more water also receive more fertilizer and the reverse is true. The application of fertilizer in precise amounts should also require a very efficient irrigation system. These go hand in hand.

In short, make your decision based upon the saving of time and labor. All of the other points are arguable and may or may not apply. 

Operating Your System. Leaving water with fertilizer in it in your irrigation lines for more than a few days can lead to algal, fungal and bacterial growth. It is best to apply fertilizer and allow fresh water to clean the irrigation lines after the fertilizer has been applied. Make sure there is a screen filter downstream of your fertilizer injector to prevent plugging of your drip emitters.