Understanding drip irrigation in Uganda
Understanding drip irrigation in Uganda, with improvement in irrigation technologies and recent changes in climate, there is an increased interest by farmers in irrigation systems, drip irrigation being water saving is most preferred although most farmers are limited by management factors
Table of Contents
Definition of drip irrigation
Drip irrigation is a technique in which water flows through special small diameter plastic pipes. These pipes are fitted with outlets called emitters or drippers. They are spaced at the same spacing to supply moisture around the roots of plants.
Water is distributed through the emitters directly into the soil near the roots through a special slow-release device.
Only the immediate root zone of each plant is wetted. This is compared to other types of irrigation (sprinkler irrigation or surface irrigation). So, this can be an efficient method of irrigation, drip irrigation requires little water compared to other irrigation methods
Benefits of drip irrigation
- Increase in yield up to 230 % keeping other factors constant
- Saves water up to 70% compared to flood irrigation. More land can be irrigated with the water thus saved.
- Fertilizer use efficiency increases by 30%.
- The crop grows consistently, healthier and matures fast.
7 advantages of drip irrigation
- Low operational costs arise from reduced labor requirements. In particular, energy costs can be reduced. This is because drip irrigation operates with lower pressure than other irrigation techniques.
- Water application efficiency is high if managed correctly.
- Field leveling is not be necessary (For sloping grounds, Pressure compensated drip lines are recommended )
- Weed growth is reduced as water and nutrients are supplied only to the cultivated plant;
- Water distribution is uniform for well designed systems
- Fertigation can easily be included with minimal waste of fertilizers.
- Foliage remains dry, reducing the risk of disease.
Five (5) limitations of drip irrigation
- Expensive, initial cost can be more than overhead systems (commercial system)
- Systems require careful study of all the relevant factors like land topography, soil, water, crop and agro-climatic conditions, and suitability of drip irrigation system and its components
- High skill is required for design, install, and operation.
- Moisture distribution problem
- Sensitivity to clogging
Suitable crops
Drip irrigation is suitable for;
Vegetables (tomatoes, chilly, capsicum, cabbages, Onions, okra, cucumber, spinach), Orchard crops( Bananas, Oranges, Mangoes, Lemons, Pineapples, Watermelons, etc), Plantations( Tea, coffee ) and flowers, where one or more emitters can be provided for each plant.
Generally, high-value crops are recommended because of the high capital costs of installing a drip system.
Suitable soils
Drip irrigation is suitable for most soils. On clay soils, water must be applied slowly to avoid surface water ponding and runoff. On sandy soils, higher emitter discharge rates will be needed to ensure adequate lateral wetting of the soil.
Types of drip irrigation Emitters
Emitters (also referred to as “drippers”) are classified into groups based on their design type and the method they use to regulate pressure.
Emitters are installed on the pipe and act as small throttles, assuring that a uniform rate of flow is emitted. Some are built into the pipe or tubing, others attach to it using a barb or threads. The emitter reduces and regulates the amount of water discharged.
Drip irrigation emitters are offered in two basic categories: Pressure compensating and non-pressure compensating. Generally spoken, all drip irrigation emitters are pressure compensating to some degree and most are designed to work best at 0.5 to 2,0 bars of pressure.
Pressure compensating (PC) emitters are designed to discharge water at a very uniform rate. They perform consistently over a very wide range of water pressures. They provide the same flow under varying input pressure and landscape conditions. PC emitters are best used on plots that have drops in elevation which would then cause an increase in pressure.
Non-pressure compensating emitters output varies with changes in elevation and pressure. As pressure increases, the more flow the drip emitter emits. These drip emitters are best used where the landscape terrain is flat and level. They are ideal for areas with very little elevation changes and consistent pressure. Non-pressure compensating emitters use an internal labyrinth design. This design reduces the velocity in the flow of water over a very short distance.