Drip irrigation is an effective system that uses water most efficiently to produce vegetables and other crops during drought periods. Small-scale farmers in semi-arid areas who are already using the system are finding the technology to be very appropriate and suitable for production of fresh vegetables, field and tree crops throughout the year.
The system is easy to explain:
In drip or trickle irrigation, water is allowed to drip to the soil around the plant roots. Water flows out very slowly in drops from a small-diameter plastic pipe fitted with outlets. This means that water is applied only to that part of the soil immediately surrounding the plant.
There is no water wasted.
There are different types of drip pipes. Some have the outlets at a distance of 20 cm or 30 cm apart. You plant the seedlings near the hole in the drip pipe. The spacing between plants depends on your crops. Cabbages need a spacing of 30 cm between the holes, lettuce or onions require 15–20 cm.
Drip irrigation allows you to produce crops the whole year – much more compared to rain fed irrigation. It has many other advantages:
- It is very efficient; this is because water soaks into the soil before it can evaporate or run off.
- Water is supplied to the soil around the plant. This means that less water is wasted, while high moisture conditions are maintained close to the roots of the plant. This makes drip irrigation appropriate for areas where water is scarce.
- Drip irrigation is easy to install and can be inexpensive if locally available materials are used.
- It allows you to add soluble nutrients into the water, so they can feed the plants directly. This economises on your fertilizer use, and is called ‘fertigation’.
- It gives you a higher yield because you can plant on both sides of the pipe.
- It helps reduce diseases associated with excess moisture on some plants: With drip irrigation you do not wet the leaves. Fungal spores need hours of leaf wetness to develop.
- Drip irrigation can be used in fields that have uneven landscapes.
- It decreases weed populations. Since water is applied close to the roots of the plants, the soil surface between\ rows is dry, so weeds cannot grow.
- The drip irrigation system does the watering without any labour, reducing costs
Farmers should know the type of crops and soils before making a decision on which drip irrigation system to buy.
There are many drip irrigation components available. Choosing a particular combination depends on various factors. Using clean water is very important. Water from ponds, rivers and wells may contain small particles that can block the holes that release water to the plants. It is necessary to have a filter to remove these particles. If there is no money for a filter, you can let the water run through a piece of cotton or a sock when filling the bucket or the drum.
The best approach for small-scale farmers is to keep their systems as simple as possible. They should try to wet only the areas close to the desired plant, so that the roots can easily access the water. It is important to realize that the larger the plant, the more the water it will need; the number of holes on the pipe (emitters) that discharge water to the plant may need to be increased, depending on the type and size of the plant. The system might need to run more often during dry weather than during wet or humid conditions. The type of soil also determines the number of emitters to be used. In sandy soils, the pipes need to be closer together than in clay soils.
The bucket kit system
This system is ideal for growing vegetables in small home gardens during the long dry season. The bucket kit consists of fittings and 30 metres of irrigation drip tape connected to a 20-litre bucket. The bucket is placed at least 1 metre above the ground so that gravity provides sufficient water pressure to ensure even watering for the entire crop.
Water is poured into the bucket twice daily and passes through a filter; it fills the drip tape and is evenly distributed to 100 watering points.
The multi-chambered plastic drip tape is engineered to dispense water through openings spaced at 30 cm. A seedling is planted at each wet spot so that all the moisture is absorbed directly by the plant roots. Two bucket kits will produce more than enough vegetables for a family of seven.
The drum irrigation system
The drum system will cover a garden 6.5 metres wide and 16 metres long. The drum kit is used to cover five planting beds and therefore the plant population depends on the type of crops grown. Water is supplied from a 200-litre drum that is fixed on a platform at a height of at least 1 metre above the ground.
The 1/8 farm system
This system covers 1/8 of an acre (a 15 metre x 30 metre plot). A platform 2 metres high is constructed to create enough water pressure. A drum with a capacity of 1000 litres would be ideal to supply enough water per day.
Simple operating system
How to maintain your drip irrigation pipes
For a drip irrigation system to work well, there is need for constant maintenance so as to remain efficient and operate at the optimum. A farmers should:
- Use clean water to avoid clogging the water emitters.
- Be careful during farm activities like weeding to avoid damaging the water pipes, hoses and drip pipes.
- Inspect the system on a regular basis so as to detect any destruction from pests (such as termites, rodents), blocked emitters, and leaks that cause water loss.
- Ensure the filters are cleaned regularly.
- Make sure you put away the system and store it when not in use.
- Use mulch (dry plant material like grass) between the plants to minimize water loss through evaporation and reduce the growth of weeds.
With all the gains that can be achieved through these measures, changing to drip irrigation can increase food production, especially where irrigation has not been explored before. There are numerous economic and social advantages when farmers use drip irrigation