Drip Irrigation

Why:

This is how we traditionally water our plants. Almost 60% of water used in traditional gardening is lost due to evaporation. With drip irrigation, we are ensuring these gain points:

  • Ensures that the water percolates to the roots of the plants, with a single targeted point kept moist - as opposed to a large wet area caused by the horizontal spread of water during piped irrigation.
  • Reduces effort of irrigating a garden patch with the pipe. The staff only need to switch on water from the tap and shut it off after a prerequisite duration. Ex - Can add fertilizers and supplements easily and push it through the drip pipes
  • Reduce growth of weeds as only one area near the plant gets water.

There are 2 types of drip irrigation we use, and each with a different purpose.

  • Bottle based drip irrigation is suited for far placed/spaced pots or to give students an experiential learning into the benefits of drip irrigation
  • Drip pipe based drip irrigation is suitable for large gardens or long lasting systems at school and home.

Bottle based drip irrigation

Figure 1 Demo bottle drip irrigation. Label has been left on to serve as an indicator of water levels.

  1. Remove the plastic cover around the bottle, and discard the plastic cover appropriately.
  2. Using a ball pin (THIS IS A VERY IMPORTANT POINT. ANY HOLE LARGER THAN A BALL PIN HOLE WILL RELEASE WATER AS A THIN FLOW AND NOT AS DROPS) make ONE SINGLE hole in the centre of the cap. You will need a stone/hammer to hit the pin and make this hole. Fit the cap back on to the bottle.

  1. Cut about 2 cms off the bottom, so when you bury it, water can be poured in easily with a pipe as shown in the image depicting bottle based drip irrigation.
  2. Insert a fine mesh/cloth into the bottle, so that it acts as a filter and ensures that the hole is not blocked from the inside by grime/fine sand/dust in the water
  3. Mount the bottle on a stick/wall and measure the time taken to empty completely. This is your calibration.

  1. If the hole is right, the flow will be like this:

Figure 2 Note - this image indicates how it drips water. We have used the bottom of the bottle to make the hole, and not the cap as suggested above for better illustration purposes.

  1. Bury the bottle at-least 6 inches into the soil, as this is the typical depth of a sapling’s root.

Finer points to consider:

  • Understand kind of plant – and its water requirement before picking size of bottle (0.5l, 1l, 2l)
  • This activity is meant to give students a first hand experience of how drip irrigation works and also involve the gardening staff (get the plant’s water requirement from them with the students).
  • Communicate clearly and sufficiently that only used PET bottles are being employed in this activity. Don ‘t remove them.
  • Algae might grow inside the apparatus, but is not a cause of concern.
  • THIS IS NOT A LONG TERM SOLUTION. IT IS ONLY FOR EXPERIENTIAL LEARNING.

Drip pipe based drip irrigation

This is a durable system, capable of being left in place for years. It uses water fed through a pipe and uses drippers (calibrated to release a fixed quantity of water every hour).

A dripper ensures that fine dust is trapped and a pre-calibrated amount of water is released into the environment. However, note that this depends on the pressure of the water. If there is high pressure, install a backflow-cum-pressure regulator.

Understanding drippers:

Figure 3 Dripper from above - notice spout from where water is dripped, the blue cap from which the flow controller cum filter can be accessed and the large black base projectile with which you can press the dripper into the drip pipe. This is a 8 litre dripper as indicated on the blue cap.

Figure 4 The insides of the dripper. The hole in the black base allows water to enter the dripper from the pipe. The white rubber washer and the maze like structure to the hole in it ensures limited flow of water and filtration. The hole in the washer is connected to the spout on the blue cap. Incase there is either NO flow or Excess flow of water (for reasons besides water pressure), check the washer.

There are 2 methods of doing this pipe based drip irrigation.

  • Surface Drip irrigation
  • Sub Surface – used in countries like Israel to prevent further loss of water due to evaporation from the spot where water is dripped. This system features the pipe buried 6 – 8 inches into the ground, so that there is no loss of water due to evaporation.

How to install sub surface pipe drip irrigation:

  1. 6 inches away from the plants, dig a 8 inch deep trench which is as flat as possible. However, with buried stones and roots, this trench is bound to be uneven. The gap between the trench and the plant is to ensure that there is no damage to the root of the plant.

  1. Put a layer of fine jelly to prevent sand from going into the drippers and lay the pipe. This jelly layer can help even the trench bottom out, making it flat for the pipe to sit on.
  2. Cap one end and leave enough spare pipe on the ground on the other end of the trench. This spare pipe will be the inlet.
  3. Adjacent to the plant, insert the dripper into the bottom of the pipe. Use the 3 images below to act as the guide on how to insert the dripper. You just need to hold the sides of the pipe and push in the dripper from the bottom.

  1. Install the filter and backflow-cum-pressure regulator between the inlet of the drip pipe and the inlet of water.
  2. Test by releasing water and seeing if all the drippers work.
  3. If all drippers are getting water, cover with sand and demarcate the line followed by the drip pipe so as to prevent any damage while digging to replant.

Installing surface drippers

  1. Draw the pipe out next to the plants, and cap one end. Leave the other end open so that you can connect it to the water inlet.
  2. Use a plastic tag and secure the pipe to the plant. Ensure the tag is installed in such a way as to secure the pipe in place and is not too tight.
  3. Install the dripper as shown in the images above.
  4. Test and leave.