Tree crop irrigation – Dripline vs sprinkler

Tree crop irrigation – Dripline vs sprinkler

Published On: February 21, 2024441 words
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Published On: February 21, 2024441 words

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Author: Jamie Zapp

Position: Netafim ANZ national agronomist
Location: Bundaberg, Queensland
Email:  Jamie.zapp@netafim.com

As a Netafim agronomist, I am often asked if I would recommend dripline or sprinklers for tree crop irrigation. As Netafim make and sell both I feel I can comment in an unbiased way.

All tree crops can be irrigated by either driplines or under tree sprinklers. Each system type has it’s own pros and cons that should be considered for each project. Considerations include: water availability, soil type, crop rooting depth, any existing irrigation infrastructure and the grower’s experience and farming practices.  There is no universal answer, however I can help guide you through the complex decision making process.

DRIP LINE
PROS

  • Highest water use efficiency due to lowest evaporative losses.
  • Smaller pumps and pipe possible as system flow rates are lower.
  • Lower installation costs- simply unroll along the ground.
  • Best able to cope with high salinity water due to lowest evaporative losses.
  • Output/ distribution not affected by obstacles- low branches.
  • Irrigation unaffected by wind.
  • Highest control of fertigation delivered to root zone due to smaller soil volume wet.
  • Blanking clips can block unwanted emitters between young trees. These clips are removed as tree grow to increase wetted area.

SPRINKLERS
PROS

  • The wetted area is determined by swivel selection. Wetted area is independent of soil type.
  • Greater soil volume wet- more insurance against dry stress of trees.
  • Larger root area.
  • Less likely to suffer blockages due to larger orifices and higher flow rates.
  • Less filtration required.
  • Better for establishing cover crops under trees.
  • Unaffected by compost or mulch spreading.
  • Encourages organic matter decomposition.
  • Small radius deflectors are a sprinkler feature for young trees, easily removed to increase the wetted area as trees grow.

CONS

  • Wetted area is a function of soil type. Best to match emitter spacing and output to soil type.
  • Smaller wetted soil volume means less water stored as insurance.
  • Greater risk of emitter blockage due to particles or poor water chemistry.
  • Dripline must be not be covered by mulch or else emitters may suffer root penetration.
  • Greater attention needed on irrigation scheduling due to a smaller volume of soil holding moisture.
  • Does not encourage surface organic matter decomposition.

CONS

  • Lower water use efficiency than dripline due to higher evaporative losses. 15-25% losses typical.
  • Higher water and pumping costs as more water needs to be applied.
  • High installation cost due to higher assemble labour costs
  • Higher maintenance requirements.
  • May grow larger trees for no extra yield.
  • Fertigation possible- but not optimal. Larger soil area covered reduces fertigation precision.
  • Output pattern affected by wind.
  • Encourages weed growth- especially around small trees