Drip Irrigation for Vegetables in Ghana

The bucket that runs dry by nine in the morning

Walk onto a vegetable plot in Ghana in February and you will usually find the same thing. A woman or a young man is carrying water from a stream or a borehole in buckets balanced on the head, pouring a cupful at each plant, and walking back for more. By nine the buckets are empty, the tomatoes are under strain and the okra has stopped setting pods. The plot is small, the water is limited and the work is hard.

Drip irrigation is the answer that many of those growers come to, and it is worth understanding before you spend a cedi on pipe. Water is delivered slowly through small emitters, straight to the root zone, instead of being thrown over the whole bed. The soil around the plant stays damp, the leaves stay dry, and very little water is lost to the air or to the gaps between plants.

We are a day-old chicks hatchery, and drip kits are not something we sell. We write about them because farmers who buy chicks from us often keep vegetables or a few fruit trees on the same land, and the dry months are when those plots struggle. Getting the water right on a small plot can free time for the birds, and that is worth thinking through before the first dry spell.

How drip differs from the can and the furrow

Three ways of watering are common on Ghanaian vegetable plots: the watering can, the furrow or flood, and drip. They are not equally efficient, and it helps to see where the water goes in each.

• The watering can is flexible and needs no kit, but the water lands on the leaves and the bare soil as well as the root zone. Hand watering is slow, so most growers water too little, too late in the day, or too much on one plant and not enough on the next.
• The furrow runs water down channels between the beds. It suits flat ground with good supplies, but a lot of water soaks deep below the roots or evaporates from the wet surface, and the first beds get more water than the last.
• Drip applies small, steady amounts close to each plant. The wet zone is smaller and more even, the leaves stay dry, and you can run the system for a set time rather than guess. Fungal leaf spots tend to be less of a problem, because the foliage is not sprayed every day.

Drip has its own weak points. It needs a water source you can lift or pressurise, it needs filtering, emitters can clog, and rodents or ants will chew through lines that are left on the ground. It also works best when you know how much each bed needs, which is why a simple water plan matters more than the kit itself.

Choosing a system that fits the plot

Choose the simplest system that can do the job on your ground. A bigger system is not better if you cannot keep it clean and running. The table sets out four common arrangements on small and medium plots.

For most small plots near a borehole or a rain store, a gravity kit is the place to start. It has no moving parts, it is easy to repair, and you can add to it as the plot grows. Pump-fed or solar kits make sense once you can show that the water is saving time or lifting the yield on the beds you already have.

Water source, filters and pressure

Drip depends on steady, clean water. Before you buy anything, check where the water comes from. Stream water usually carries sand, algae and organic matter. Borehole water may carry iron, which can deposit in the emitters as an orange crust. Harvested rainwater is usually softer and cleaner, but the tank and the gutters can carry leaves and dust into the line.

A filter stops most of that from reaching the emitters. A screen filter or disc filter rated at around 120 mesh or finer is the usual choice for drip tape. Put it straight after the tank outlet, and clean it on a regular schedule, because a blocked filter starves the whole line.

Pressure is the other constraint. Each metre of water height gives roughly a tenth of a bar. Drip tape is commonly rated to run at about half a bar to a bar, which is around 5 to 10 metres of head, so a tank a metre or two off the ground will feed only short lines or low-pressure emitters. Check the rating on the product you buy, and plan the line length so that the flow stays even at the far end. If the first emitters run strongly and the last ones drip, the line is too long for the pressure.

Laying the lines and spacing the emitters

Drip tape is the cheapest and most common option on vegetable beds. It is a thin-walled pipe with emitters built in at fixed spacing, usually about 20 cm for vegetables in loam and sand. Button emitters on a larger pipe are sturdier and suit tree crops or beds where the water must go deeper. Many drip tapes emit around 1 to 2 litres an hour per emitter, and button emitters are often 2 to 4 litres an hour. Confirm the figures on your product, because they decide how long you run the system.

Lay the line on the surface, or just under a light covering of mulch, with the emitters facing up. Peg it down so that wind and rodents do not drag it off the bed. Run the line along the bed, not across it, so the water spreads evenly, and keep the end of each line open to flush out sediment. Cap the far end once the system is running.

Two rows of tape on a 1.2 m bed, set about 30 cm apart, give a good spread for most vegetables. Keep each line within the maximum length given by the maker, because pressure falls along the tape and the far plants get less.

How long to run the water

A drip system is only as useful as the schedule behind it. The rule of thumb is to replace the water the root zone has lost, usually the top 30 cm of soil for most vegetables, and no more. Too little water wets only the surface. Too much pushes nutrients below the roots and wastes the pump or tank you have filled.

Here is a worked example with the assumptions written out, so you can change them for your own plot. Say you have a bed 20 m long and 1.2 m wide, which is 24 square metres. You want to add 20 litres per square metre, which is a 20 mm top-up. That is 480 litres to deliver. Two tape lines with emitters at 1.5 litres an hour and spaced 20 cm apart give five emitters per metre of line each. Across the 20 m length that is 100 emitters per line, and 200 emitters for both lines together. At 1.5 litres an hour each, the bed takes about 300 litres an hour, so the run time is about 1.6 hours.

Check the result by feel. Dig a small hole with a trowel the next morning, and the soil should be damp to about 20 to 30 cm. If it is wet only at the top, run longer. If it is wet to the bottom and the drainage below the roots is poor, run shorter. Sandy soils need more frequent, shorter runs than heavy clay, and the mulch on the bed changes the answer too.

Keep a simple log of the run times, the date and what the weather did, because the schedule you need in March will be different from the one you need in January.

Clogging, cleaning and flushing

Most drip problems come from blocked emitters, not from broken pipe. Sand, algae, iron and fine organic matter build up slowly, and an emitter that drips at half its rate is usually not dead, just partly blocked. Find the weak spots by walking the line during a run and looking for the plants that are drier than the rest.

Flush the lines at the end of the line on a regular schedule, perhaps once a week in the dry season and after each new fill of the tank. Open the cap at the far end until clear water runs out, then close it again. Clean the filter at the same time. If the water is known to carry iron or algae, follow the maker's guidance on cleaning the lines, and do not use a strong chemical without reading the label and the instructions for the product you have. Keep records of any cleaning you do, so you can see whether the blockage is getting worse.

Store the lines out of the sun and rodents when the season is over. Coil them loosely, drain them and keep them in a dry place. Tape left in the sun for a whole dry season can crack at the seams, and a torn line costs more to fix than a clean one costs to store.

Pests, rodents and what drip does to disease

One of the real benefits of drip is that the leaves stay dry. Fungal leaf spots and some bacterial diseases spread in splashed water and in wet foliage, so a bed watered by hand every evening can carry more disease than one watered through the soil. This does not mean drip cures disease. Soil-borne wilt still moves from plant to plant through the soil and the tools, and the rotation rules in our guide to crop rotation in Ghana still apply.

Rodents and ants are the common nuisance. Rats and cane rats chew through the tape and the connectors, and ants build nests under the line and block the emitters with soil. Keep the lines covered where you can, clear the margins, and inspect the beds weekly. Cutworms and other soil pests can also cut seedlings at ground level, so a young transplant may need a check after the first week.

If you see wilt, pull the plant and the soil around its roots, and do not compost the infected material in the same bed. Follow your agric extension officer's advice on control, and keep the record in the same notebook as the irrigation log.

Drip and mulch work together

A drip system and a mulch layer are a good pair, because each helps the other do its job. The mulch slows evaporation from the surface, so the water the emitters deliver stays in the root zone for longer. The drip keeps the mulch from getting soaked each time, which means it does not rot as quickly and does not go mouldy at the base of the plant.

Lay the tape first, then spread the mulch over it, keeping the stems clear as explained in our guide to mulching to hold soil moisture. On beds of tomato or pepper many growers lay a sheet of black polythene over the tape and cut planting holes in it. That warms the soil early in the season and keeps the water going to the plants rather than running off the top, though it does not feed the soil in the way that organic mulch does.

Check the beds after each rain, because a heavy shower can wash mulch off the tape, and loose material can cover the emitters and cause uneven wetting.

Keeping the birds' water separate

On a mixed farm the drip tank and the poultry water supply often come from the same source, and that is where mistakes happen. Irrigation water does not need to be drinking quality, but the birds' water does. Do not let the irrigation line share a tank or a pipe with the drinkers unless the water has been treated for birds and tested.

Keep the two systems physically separate, with a clearly labelled tap for the irrigation line and a different tank or a different pipe for the birds. Our notes on water quality for poultry in Ghana and water supply and storage for poultry explain what the birds need and how to keep the supply clean.

Also keep fertiliser out of the drip tank unless you know exactly what you are doing. Fertigation, the practice of feeding fertiliser through the irrigation line, can work well, but it needs proper injection equipment and a clear plan. Adding fertiliser to a gravity tank by guesswork is how a pipe ends up blocked and a bird ends up with water it should not drink.

A checklist for the first dry season

1. Measure the source, the head of the tank and the pressure at the start of each line, and write the figures down.
2. Choose tape or emitters rated for the pressure you can deliver, and check the maximum run for each line.
3. Fit a filter straight after the tank outlet, and clean it before each run.
4. Lay the lines along the beds, peg them down and open the far ends until the water runs clear.
5. Time a run, dig a test hole the next morning, and adjust the time until the root zone is damp to 20 to 30 cm.
6. Flush the lines weekly, and log the run times and any blockages.
7. Mulch the beds over the tape, keeping the stems clear.
8. Keep the birds' water on a separate line and tank, and check the labels.

Is drip worth it on your plot?

The cost of a drip system is the kit, the filter, the tank or pump, the labour to lay and maintain it, and the energy or fuel to run it. The return is the crop you get from water you did not have to carry, the time you save, and the beds you can keep going in the dry season. Work it out for your plot with figures you can check.

Use a simple sum. Take the cost of the kit and divide it by the number of years you expect it to last, then add the yearly running cost. Compare that with the value of the extra yield and the hours saved, using prices from your local market. Prices for pipe, emitters, filters and pumps change, so check your local suppliers and current rates before you commit.

Some support may be available, such as input or irrigation schemes linked to Planting for Food and Jobs or the district agriculture office. Check the current terms, the eligibility rules and any cost-sharing before you assume a subsidy. Do not budget on a scheme you have not confirmed in writing.

Where drip fits on a mixed farm

Drip is one more tool for a mixed farm, and it works best when it is part of a plan. Water for the vegetable beds, water for the birds and water for any fruit trees each need their own supply and their own schedule. The farmers who keep all three running through the dry season tend to start small, learn one system well and grow from there.

If you are planning to add birds to a holding that already grows vegetables, our day-old chicks range covers the main meat and layer lines, and you can see the starting prices on our prices page. Ross 308 and Cobb 500 begin from GH₵20 per bird, Hy-Line Brown from GH₵23 and Sasso from GH₵13. Compare the breeds and then place an order, or WhatsApp us on +233 24 915 1503. Our partner page explains how farmers work with us as the flock grows.

For the crops themselves, our notes on growing tomato in Ghana and growing maize in Ghana set out the stages where water matters most.

Questions farmers ask