Friday, June 19, 2015


We are exploring a new thing this year... called fertigation. It is the concept of fertilizing through a drip irrigation system. There are several advantages:

  • More efficient - fertilizes the plants directly, not the entire ground
  • Simpler - fertilizing is as simple as pouring a mix in a bucket and click a switch
  • Feeds the roots all season - Fertilizer can be added with each watering, for the life of the plant
  • Prevents "washing out" of nutrients from over watering
And there are other advantages... it is a fascinating concept. Once you have drip lines installed, fertilizing and watering become almost totally automatic.  

For the main garden section, we chose to go with a metered injector. This is a little device that measures the water flowing through, and adds a precise amount of fertilizer to make a predetermined mixture of fertilizer to water. Its not so much adding fertilizer to the ground as it is filling the irrigation water with nutrients. This unit has its own on / bypass switch on top so it can easily be set to not run when not fertilizing. 

We simply added this device in front of the main valve distribution, and added a buckets for the fertilizer. Then just mix and watch!

Initially we ran it manually, meaning we would mix the fertilizer into  the bucket, and manually turn on the valves to water / fertilize until the fertilizer was used up. Eventually we will set it up so that once a week we just mix a big batch of fertilizer in a larger drum, and let the system run through the normal watering cycle all day. unattended fertilizing!

Here is the completed setup. The distribution valves are sitting on a nice table (old duck shelter) with hoses gently bent to prevent kinks. The injector sits on the right with the supply line, and the bucket of fertilizer below on the pallet. The timer is behind the valves. 

A closeup of the injector system. That black cylinder connected to it is the water filter. 

This injector has moving parts. More prone to "wear" but more accurate on delivery at low water pressure.  When running, this system only has about 10 to 20 psi on the feed line, so we had to be careful with which injector to use. 

It is currently set to a 2% mix, meaning for every 100 gallons of water flowing through, it will have mixed 2 gallons of fertilizer mix. We dilute the fertilizer mix based on this to match the manufacturer's recommended dosage.  

Here is a quick video of the machine in operation.

By the way, all the products you see here, including the drip tape itself is easily available online  through Drip Depot, based right here in southern oregon. 

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