Boreholes and Irrigation for Ghana Farms

A dry field in March, and a neighbour with green beds

Walk the vegetable belt outside Tamale in late March and the difference between farms is obvious from the road. One field is cracked and grey, with the maize stubble still standing. The next is green, with okra, onions and tomatoes in neat beds, and a black pipe running from a borehole in the corner. The soil and the seed are not very different. The water is.

Irrigation is the difference between one harvest a year and two or three, and it is also the difference between a crop that sells in the lean months and one that rots in the glut. In the north the dry season runs for most of the year outside the rains, and in the south the minor dry spells and the harmattan can stop a crop just as surely. A farm that can water on demand has a planning advantage that no amount of goodwill can give it.

This guide covers the water itself: where it comes from, how to get a borehole legally, how much water a crop really uses, which irrigation method suits which farm, and what the water must be like before you put it on a crop people will eat. Poultry farms have a similar water problem, and the same borehole often serves both. Our broiler water management guide covers the birds' side of the story.

Where the water can come from

Most Ghanaian farms draw on one of five sources. Each has its own cost, its own permit and its own weak point, and the best choice depends on how much water you need and how far it has to travel.

• A drilled borehole. The most reliable source for a dry season, and the one that needs the most paperwork and the most money up front.
• A hand-dug well. Cheaper, shallower and often shared. Its yield falls quickly in a dry spell, and it is easily contaminated from the surface.
• A dugout or dam. Water collected from runoff or a stream. It can hold a season's supply, but it evaporates, silts up and needs a permit where the law requires one.
• A river or stream. Free to draw from in principle, but the flow falls in the dry season and the rights to draw large volumes are regulated.
• Harvested rainwater. Roof and runoff water stored in tanks or pits. It suits small beds and drinking water rather than a large irrigated block.

Check the local situation before you choose. Ask the district assembly and the Water Resources Commission what is allowed in your area, and ask your neighbours which source has held up in the last dry season, rather than the one that worked in a wet year.

Drilling a borehole legally in Ghana

Drilling for water in Ghana is regulated. The Water Resources Commission issues drilling licences under its regulations, and drilling without one is an offence. The Commission's own advice is that well work should be done by a qualified driller with the right equipment, not by a mason or a plumber with a hired rig. Check that the driller is registered before you sign a contract, and ask for the licence number in writing.

Drilling licences must be renewed. A driller whose licence has lapsed or been refused renewal may not start the work, so a driller who is ready to start tomorrow and cannot show a current licence is a warning sign. Ask for the licence, check it with the Commission, and keep a copy in the farm file with the contract, the drilling log and the test results.

Ask the Commission whether the water you plan to take needs a permit for abstraction, as well as a drilling licence. Those are separate questions. Large volumes for irrigation are the usual reason a permit is needed, and the answer depends on the volume and the aquifer. Check the current rules with the Commission before the rig arrives, because a well drilled without the right permit can be stopped even when the hole is perfect.

Keep your land papers in order too. Do not sink a borehole on leased land unless the lease covers the works, the water and the right to remove the equipment. A borehole is a fixed investment, and the landowner may claim it at the end of the lease if the agreement does not say otherwise.

Testing the yield before you buy the pump

A borehole that looks deep is not necessarily a productive one. The useful number is the yield: how many litres a minute the hole can give over a sustained period before the water level drops too far. A driller should carry out a pumping test after the hole is completed, and the test should run long enough to show what the aquifer does over a working day.

Ask for three figures from the test: the static water level before pumping, the pumping water level at the end of the test, and the yield at that level. The gap between the static and pumping levels is the drawdown. A small drawdown means the aquifer is recharging well and the pump can run for hours without starving the hole. A large drawdown means the hole will struggle in the dry season, when the water table is lowest.

Size the pump to the yield, not to the hole's depth. A pump that draws more than the hole can give will dry it out, damage the pump and leave you with an expensive repair. Ask the driller for the recommended pump rate and the setting depth, and check both against the flow you need.

A worked water budget for a half-hectare vegetable plot

The most useful habit you can build on an irrigated farm is a daily water budget. Work out how much water the crop uses, divide by how efficiently the method delivers it, and check that the borehole can keep up. The figures below are a method with labelled assumptions, not a substitute for local data.

Assume a half-hectare plot, which is 5,000 square metres. Assume a crop water use of 5 millimetres a day at the hottest point of the season, which is a common planning figure for vegetables in hot weather. One millimetre of water over a square metre is one litre, so 5 millimetres over 5,000 square metres is 25,000 litres, or 25 cubic metres, a day.

Now allow for the method. A drip system that delivers water to the root zone might be 85 to 90 per cent efficient, so you need about 28 cubic metres a day. A furrow system that floods the bed, with more losses to soakage and evaporation, might be 50 to 60 per cent efficient, so the same plot needs roughly 42 to 50 cubic metres. Choosing drip instead of furrow cuts the daily pumping need by roughly a third to almost half.

Finally, check the pump. If you can run the pump for six hours a day, 28 cubic metres needs a flow of about 4.7 cubic metres an hour, which is about 78 litres a minute. Compare that with the yield from the pumping test. If the borehole gives less than the flow you need, either the plot is too large for the hole, or the method must change, or the hours must increase.

Replace these assumptions with your own. Local extension officers and the Ghana Meteorological Agency can give better figures for the crop, the season and the soil, and the figures change through the year. Recalculate each month rather than once a year.

Choosing the irrigation method

There is no best irrigation method for every farm. Each one trades water, labour, cost and skill against the others. The table below sets out the main options for small and medium farms in Ghana.

For most vegetable growers, drip gives the best return on the water, because it puts the water where the roots are and leaves the leaves dry. It needs a filter, a pressure regulator and regular cleaning, and the pipes must be protected from the sun and from animals. Furrow is cheaper to set up and is common in the north, but it wastes water and can waterlog the soil, so it suits crops that tolerate wet feet.

Sprinklers are useful for field crops in the open, but they throw water into the air in the hot afternoon, and they wet leaves that may carry disease. Do not use overhead watering on leafy vegetables that are eaten raw without washing, for reasons covered in the next section.

Testing the water before it touches the crop

Irrigation water carries things that do not show. Salt in the water builds up in the soil and cuts yields over several seasons. Iron can block drip emitters and stain the leaves. Faecal bacteria from a nearby latrine or animal yard can end up on vegetables that people eat raw, which is a serious health risk for the buyer and the family.

Test the water once before you start, and again each year or after any change in the source. A basic test covers electrical conductivity for salinity, pH, iron and the presence of faecal bacteria. Use an accredited laboratory, ask it to explain the results in plain language and keep the certificate with the farm file. Your district office can tell you which laboratories are used locally.

Protect the source too. Fence the borehole platform, keep latrines and animal pens downhill and away from it, and keep the pump house clean. A borehole that was clean when drilled can be contaminated by a leak from a septic tank or a flood that runs through an open cover.

If the water is marginal, choose the crops that tolerate it, and irrigate the soil rather than the leaves. Ask an extension officer which crops suit a slightly saline or iron-rich source, and avoid putting raw leafy greens under sprinklers in a well-used field.

Power for the pump: grid, diesel, or the sun

The pump's power source shapes the cost of every litre. Grid power is cheap to run where it is reliable and expensive to lose when it is not. Diesel and petrol pumps are flexible and easy to set up, but the fuel bill grows with every hour of pumping, and the fuel has to be carried and stored safely. Solar pumps cost more at the start and very little to run, provided the tank is sized for the day's water.

Many farms run a hybrid. A solar pump fills a tank during the day, and a small petrol or diesel pump covers the evening or a cloudy spell. Our guide to solar power on farms covers pumping, tanks and the battery question in detail, and our generator backup guide covers the back-up side from the poultry perspective.

Whatever the source, the pump needs a float switch or level control, a non-return valve and a pressure gauge. The first stops the pump running dry, the second stops the water running back down the pipe, and the third tells you when the pipe is blocked. Ask the installer to show you each one working before you leave.

Public schemes and what they can offer a small farm

Some irrigation in Ghana is public. The Ghana Irrigation Development Authority runs and oversees larger schemes, including the dams and canals in the north, and it has been developing new schemes with support from development partners. Schemes such as the ones at Tono, Vea and Bontanga are well known in the north, but availability for new farmers changes, and the allocations are subject to conditions.

Ask the Authority's regional office which schemes are open to new farmers, what the water charges are, what the rules on plot size and crop choice are and what the application involves. Check current terms before you plan around any scheme, because a public scheme that is open this year may be full next year.

Government input programmes, including Planting for Food and Jobs, change their packages from year to year. Check with your district agricultural office whether any package open this season includes irrigation support, and what conditions apply, rather than assuming that last year's package still applies.

Where poultry shares the borehole

A borehole on a mixed farm usually serves the birds as well as the crops. Chicks and grown birds drink a lot of clean water, and heat makes the demand jump. The pump that waters the vegetables is often the same pump that fills the drinkers, so the two loads must be planned together. A tank that stores the day's water for both is the simplest way to keep the house supplied when the pump is off.

Poultry manure is useful on irrigated beds, but it has to be composted or dried first, and it should never be put into the drip line where it can block the emitters. Our guide to using poultry manure as fertiliser covers the safe way to apply it, and our guide to linking poultry, crops and fish shows how the water and the manure can move between the two systems.

If you are starting birds alongside an irrigated crop, our day-old chicks range is the place to begin. Starting prices are on our prices page, and you can place an order through the order form or on WhatsApp at +233 24 915 1503.

Keeping the system running through the season

An irrigation system is only as good as its weakest part, and the weak parts are usually the filter, the emitters and the pump's seals. Clean the filter every time you irrigate on a dusty farm, and flush the drip lines at the end of each run. A blocked emitter starves a single plant, and a dozen blocked emitters can cut a bed's yield without anyone noticing until harvest.

Keep a simple log. Write down the pump hours, the flow, the water level in the borehole when you can read it, and any repair. A sudden drop in flow with no change in hours usually means a blockage or a worn impeller, and the log will show you when it started. Check the pipes for rodent damage and sun cracking every few weeks, and replace the sections that have split before they leak in the middle of a dry spell.

Plan the dry season repairs in the wet season, when the pump is idle and the crop is in the ground. Order spares early, because a part that takes three weeks to arrive can cost a whole planting window.

A checklist before you drill or irrigate

Take this list to your driller, your installer and your district office. A reputable professional will answer every line in writing.

• The driller holds a current Water Resources Commission licence, and you have the number on file.
• You have checked with the Commission whether abstraction needs a separate permit for the volume you plan.
• The land lease covers the borehole, the pump house and the right to remove the equipment.
• A pumping test has been carried out, and you have the static level, the pumping level and the yield.
• The pump is sized to the yield, with a float switch, a non-return valve and a pressure gauge.
• The water has been tested for salinity, iron and faecal bacteria by an accredited laboratory.
• Latrines and animal pens are kept away from the source, and the borehole platform is fenced.
• The irrigation method suits the crop, and the water budget has been worked for the hottest month.
• A filter, flushing routine and maintenance log are in place, with spare parts ordered before the season.

If a line is missing, fix it before the rig arrives. A borehole is one of the few farm investments that cannot be moved if it turns out to be in the wrong place.

Questions farmers ask