Emitter spacing

Emitter spacing is simply the distance between the drip emitters. This can be as close as 10 cm (4”), and as far as 1 m (40”) or more.

Two considerations are the soil type and the crop. Regarding the crop, consider the plant density and the root structure.

A handy rule of thumb – the freer draining the soil, the closer the emitter spacing needs to be.

Therefore, in sand, you would want a relatively close emitter spacing. On the other hand, in clay, the water will move further laterally, allowing you to use wider drippers.

Knowing your soils enables you to choose the right dripper flow rate (flow per dripper) and spacing (distance between drippers) for your crop. Getting this combination right is important to:

  • ensure all plants receive water and nutrients at their root zone
  • minimize leaching of water and nutrients through the soil profile
  • avoid over-watering or under watering, which leads to poor crop uniformity.

It is a common (wrong) belief that applying more water will cause it to spread further laterally. Generally, this is not the case, especially in sandy soils. By applying dye through a drip irrigation system and then cutting away the soil, we can see how water moves in the soil with different flow rates and spacing.


Application 1:

  • Low flow rate
  • Close spacing
  • Low water application

Drip line: 1 l/h (0.26 gph) drippers at 20 cm (8”) spacing
Water applied: 0.5 l (0.13 gal)

Water movement:
Spread: 18 cm (7”)
Depth: 29 cm (11.5”)



Application 2:

  • High flow rate
  • Wide spacing
  • High water application

Drip line: 8 l/h (2 gph) drippers at 50 cm (20”) spacing
Water applied: 2.0 l (0.5 gal)

Water movement:
Spread: 23 cm (9”)
Depth: 60 cm (24”)


Rohan Prince. Using dye to show water movement below drip irrigation. Department of Primary Industries and Regional Development. Government of Western Australia. (2016)

In the above test, you can see in Application 2 that using higher flow drippers and wider spacing between drippers only results in a 5 cm (2”) wider spread of water, despite applying four times the volume of water!

Additionally, there was significant water loss through the soil profile. The root zone of a tomato plant (for example) is only 25 cm (10”) deep, meaning that all water movement below this point for this crop is lost water and nutrients.

In this example, most of the water in Application 2 using the high flow, wide distance system was lost and
passed the root zone. If closer spacing and lower flow drippers were used, the water (and fertilizers) would
be applied more efficiently.

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