In-line emitters are small plastic devices. These are put inside the PE tubing at fixed distances during the making of the tubes. The water flow rate depends on the pressure. If the pressure is low, the water flow decreases, and if the pressure is high, the flow increases. These emitters are available in discharge rates from 0.8 lph to 4 lph. Surface drip systems are usually used for high-value vegetables like tomatoes, broccoli, cauliflower, and spinach.
Sub-surface Drip Irrigation
Sub-surface drip irrigation is a method to water crops through plastic tubes buried under the ground. In this system, emitters are placed at regular intervals inside the buried tubes. The design is similar to surface drip, but here the tubes are placed 6 to 10 inches (15-25 cm) below the soil surface.
This method saves more water than surface irrigation because there is almost zero evaporation. Since the water goes directly to the root zone, the seeds of weeds do not get water to grow. This system is very efficient and can save 25% to 50% of water compared to flood irrigation in open-field farming.
Micro Irrigation System: Features, Benefits
Components of a Drip Irrigation System
Surface drip irrigation is used for both perennial crops (plants that live more than two years) and annual crops (plants that live for one year). A typical system has the following parts:
- Pump Unit: This includes a pump and an electrical unit. The pump pulls water from the source and provides the right pressure to send it through the pipes.
- Main Control Unit: It has valves like shut-off, air, and check valves to control water flow and pressure. It also has a pressure relief valve to send back extra water.
- Filtration: Filters clean the water and remove dirt or debris. Disk filters are used for water from ponds or tanks that may have algae. Some units also have fertilizer tanks to give nutrients directly to plants.
- Tubing: This includes the main line, sub-main lines, and laterals. The main line takes water from the source to the sub-mains, which then send it to the laterals. Laterals are usually 13-32 mm in diameter.
- Emitters or Drippers: These devices control how much water goes to the plants. They are made of HDPE plastic. Water enters at about 1 kg/cm² pressure and comes out as drops at a very low rate.
Types of Emitters
There are mainly two types of emitters. Online emitters are small plastic tools connected to the outside of the PE tubing. You have to punch a hole in the pipe and fix the emitter’s barb inside it. The water then moves into the soil and creates a wet area based on the soil type and flow rate.
Frequently Asked Questions (FAQs)
What is an in-line emitter?
An in-line emitter is a small plastic part fixed inside the water pipe. It lets water out at a fixed speed, like 1 to 4 liters per hour.
How deep is sub-surface drip irrigation?
In this system, the pipes are usually buried 6 to 10 inches (15 to 25 cm) under the soil so water goes straight to the roots.
Does sub-surface irrigation help in controlling weeds?
Yes. Since the water is deep under the ground, the weed seeds on the surface do not get water and they do not grow easily.
What is the use of a pump in drip irrigation?
A pump is very important because it pulls water from the well or pond and gives it the pressure needed to travel through all the pipes.
Why do we need filters in the irrigation system?
Filters remove dirt, sand, and small plants like algae. Without filters, the small holes in the drippers will get blocked and the plants will not get water.
What are perennial and annual crops?
Perennial crops are plants that live for more than two years. Annual crops are those that grow, give seeds, and die within one single year.
What is the benefit of a fertilizer tank in the system?
A fertilizer tank allows you to mix plant food in the water. This way, the fertilizer goes directly to the roots with the water, which saves time and money.