Growing Cowpea and Beans in Ghana

Cowpea and common beans are not the same crop

Cowpea is the legume that fixes its own nitrogen, goes into the ground with little fuss and comes off in two or three months. Common beans are a different plant. They belong to another species, they want cooler and steadier conditions, and they are picky about heat during flowering. Growers in the north who plant one and expect the other end up disappointed.

In Ghanaian markets the names overlap. A bag labelled beans can hold cowpea, and the red and speckled types sold at the market may come from either crop. Ask the seller what the crop is and how it was grown, and put a labelled sample of each seed lot aside, so you can see later which crop you actually sowed.

This article covers both, but gives cowpea the most room, because it is the crop most Ghanaian farms can grow with the least risk. Common beans come second, with the places and conditions where they make sense.

Where cowpea and common beans grow in Ghana

Cowpea is most at home in the Guinea and Sudan savanna of the north, where the rains are short and the soils are light. It also grows in the transition belt, and in the south it is sown in the minor season and sometimes on the coast, where the rains come twice. It is tolerant of dry spells, which is why it often sits on the least fertile patch of the farm, and why it pays to give it the better ground when you can.

Common beans prefer the forest fringe, the transition zone and the cooler, higher ground of the Volta region. They suffer when temperatures spike during flowering, because the flowers drop before the pods form. They also dislike waterlogging, so keep them off the bottom of a slope and out of any hollow that holds water after a storm.

If you are unsure which crop suits your field, look at your rainfall for the last three seasons and your soil in the rainy weeks. Cowpea forgives a lot. Common beans reward a careful choice of site.

Cowpea varieties: early types and the ones buyers want

Pick a cowpea variety for its duration first. An early variety can be picked within about two months and escape the late dry spell in the north. Longer types put on more leaf and sometimes more seed, but they only pay if the rains last. In the north, early types are the safer bet for most fields, and they fit the short season that most farmers actually get.

Start with the current recommended list from CSIR-SARI. Cowpea breeding has produced early and medium types that suit the savanna, and the names change as new lines are released. Ask extension staff which early types they are recommending this season, and check that answer against the current list rather than an old one. Buy seed from a trusted source, and check the germination on the bag before you plant.

Seed colour and seed size matter to buyers. Some markets prefer a particular colour and a clean, uniform grain. Ask local traders what they buy before you plant a large block, and keep a sample of the seed so the crop matches what you intend to sell. A field of mixed seed sells for less and is harder to clean.

Saved seed and seed mixing

Cowpea seed is easy to save, and many households do it. Choose pods from the healthiest, earliest plants in the middle of the field, dry them thoroughly and store the seed in an airtight container with a little dry ash or a sealed bag, not an open sack. Saved seed drifts over several seasons, so renew from a trusted source when yields begin to fall.

Common beans: a crop for cooler, steadier ground

Common beans in Ghana usually come in two growth habits. Bush types stand on their own and finish in a single flush. Climbing types need support, usually stakes or a trellis, and they carry on flowering longer. Bush types are simpler to grow on a small plot, and climbing types give more pods where the labour and the support are available.

Plant common beans with the first steady rains, and keep them off the hot, dry patches where the flowers will drop. Sow in rows so you can weed and scout between them. Use clean seed from a trusted source, and check its disease tolerance, since anthracnose, angular leaf spot and the rust diseases can spread quickly in a wet year.

The biggest mistake with common beans is sowing them in a field that floods. Waterlogged roots rot, the plants yellow and the crop collapses before flowering. Choose a raised, well-drained site, and if the field is low, grow cowpea or groundnut there instead.

1. Pick higher, free-draining ground and keep the plot out of hollows.
2. Sow clean seed from a source the district office trusts.
3. Stake or support climbing types early, before they tangle.
4. Scout for leaf spots and pod damage every week during flowering.

Land, rhizobia and sowing

Cowpea needs little fertiliser, and it often does better without a heavy nitrogen dose, because it feeds itself through its root nodules. The nodules hold rhizobium bacteria, which take nitrogen from the air and give it to the plant. The soil ends up richer for the maize or sorghum that follows. Where the field has not grown a legume before, or the soil looks pale and thin, inoculating the seed with a suitable rhizobium product helps the nodules form.

Check whether a suitable inoculant is available from your seed supplier before the season starts. Follow the product's instructions, keep the seed out of the sun, and sow the same day you treat it. Inoculants lose their life if they dry out or sit in heat. Where none is available, rotate cowpea into a field that has grown cowpea or groundnut recently, since the bacteria may already be present.

Sow cowpea in rows about 60 centimetres apart, with two seeds per hole and the plants thinned to one about 20 centimetres apart in the row. The seed pack and your extension officer will confirm the rate for your variety. Sow at a shallow depth, about three to four centimetres, and plant after the soil has been wet by at least two steady rains.

Cowpea does not like crowding, but a thin stand loses ground to weeds. Aim for the planned spacing from the start, and replant the gaps within the first week.

Weeding and the first six weeks

The first six weeks decide the yield. A cowpea field that is weeded late loses ground to grasses and broadleaf weeds that outgrow the young plants, and the cowpea never recovers its vigour. Plan the first weeding for about two to three weeks after emergence, and the second before the plants begin to flower, when the canopy is still open enough to walk through.

Hand-weeding works well on a small plot. On a larger field, a hoe between the rows does most of the work, and a second pass on the weeds in the row finishes the job. Do not weed deeply once the plants are flowering, because you can damage the shallow roots and knock off flowers that would have set pods.

Striga can also attack some cowpea fields. Look for the small, dark plants in the ground near the roots, and pull them early before they flower and seed. A cowpea field that is rotated on a regular cycle carries less Striga, which is one more reason to plan the rotation around the legume.

Pod borers, aphids and thrips

Pod borers are the pest that most often costs a cowpea grower the harvest. The larva feeds inside the flower buds and the young pods, and a single caterpillar can ruin several pods before it pupates. Scout the flowers every week, and open a few buds to look for the small caterpillars and their frass. Pick off infested buds and pods where you see them, and act early, before the caterpillars grow large enough to move from pod to pod.

Aphids gather on young shoots and under the leaves, and they can spread virus diseases when the plants are young. Thrips rasp the flowers and the young pods, and they leave silvered, scarred pods. Pod-sucking bugs pierce the pods and leave shrivelled, discoloured grain. None of these pests is cleared by the calendar. Walk the field, look at the plants, and decide from what you see.

If you need a pesticide, follow your agric extension officer on the product and the timing, and read the label carefully, including the pre-harvest interval. Cowpea haulm and grain often go to animals and people, so the withholding period matters.

Natural enemies help. Ladybirds and lacewings feed on aphids, and a field with some diversity around it often keeps aphid numbers lower. Avoid spraying broadly where you do not need to, because you may kill the helpers along with the pests.

Harvest, picking and threshing

Cowpea pods are ready when they turn brown and dry and begin to split along the seam. Early pods on the same plant will be ready long before the late ones, so cowpea is picked over two or three rounds, not in one cut. Pick the dry pods as they mature, and leave the green ones to finish on the plant. A single harvest on a day when half the pods are green gives you grain that is uneven in quality.

Dry the pods on a clean sheet or a raised mat for a few days in the sun, turning them daily. Thresh them by beating the pods on a frame, a tarp or a clean floor, then winnow the grain to remove the husks and the dust. Common beans can be harvested once the plants are dry and the pods rattle. Pull the plants, dry them, and thresh by beating or by trampling on a clean surface.

1. Pick the dry pods as they mature, in two or three rounds.
2. Dry the pods on a clean sheet, turning them daily.
3. Thresh and winnow on a clean surface.
4. Dry the grain until it is hard and cool before bagging.

Keep the threshing area free of goats and chickens. A few minutes with an open sack and a free-ranging flock can take more grain than the rest of the day produces.

Storage and weevils in cowpea

Cowpea weevils are the most common reason a good harvest turns into a poor store. The adult beetle lays eggs on the grain, often while it is still in the field, and the larvae hatch and bore into the seed. A bag that looks clean on the day it is sealed can be half-eaten within a few months. The trick is to stop the weevils getting in, and to keep them out once they are there.

Dry the grain until it is hard and cool. Sort out broken, discoloured and insect-damaged seed before bagging. Use airtight storage, such as hermetic bags, and check the bags every few weeks by sifting a handful and looking for holes, grubs and fine dust. Keep the bags on pallets, clear of damp walls, and keep the store clean between seasons.

Use grain from the store for food or sale within the season, and keep the seed you plan to plant in a separate sealed container. Mark the bags with the lot, the date and the variety, so you know which lot to use first.

Haulm, leaves and the feed side of the farm

Cowpea haulm is one of the best fodder crops in the north. The leaves are high in protein, the stems are digestible when dry, and goats and sheep go for both. Cut the haulm when the pods are picked, dry it on a clean surface, and store it under cover in a stack that sheds rain. A haulm store carries a household's goats through the dry months more cheaply than many purchased feeds.

The grain is a different matter. Cowpea is a useful protein ingredient in animal diets, but raw cowpea contains compounds that reduce protein digestion in monogastric animals such as poultry and pigs. Heat processing reduces these compounds, so raw cowpea should not go straight into a ration. Ask a feed formulator how much processed cowpea a flock can take, and keep the share small until you have checked the results on your own birds.

If you already formulate your own rations, read our feed formulation basics and the groundnut haulm guide, which covers a similar fodder question. The cassava and soya articles on this site explain the other protein sources that sit beside cowpea in a ration, and the choice between them depends on the price and quality you can get locally.

For day-old chicks, the feed starts with a proper starter ration, not a home-grown mix. For the flock itself, our broiler and layer chick pages set out the options, and a sound starter ration is the base of everything after.

Rotation and the maize that follows

Cowpea earns its place in the rotation. It leaves the soil with more nitrogen and better structure than it found it, and it breaks the cycle of pests and weeds that builds up under a continuous maize or sorghum crop. A simple rotation of cowpea one season and maize the next is one of the most cost-effective things a northern grower can do.

Some farmers intercrop cowpea with maize, sowing the two together in the same field. The maize provides a frame for the cowpea to climb or sprawl over, and the cowpea adds nitrogen and ground cover. Intercropping is forgiving on small plots, but the maize spacing and the cowpea variety have to suit each other. Check with your extension officer before you try a mixed field for the first time.

After the cowpea harvest, leave the stubble and roots in the ground. They decay and return nitrogen to the soil. If you cut the haulm for fodder, return some of the residue as mulch where you can, and add manure if you have it. The field you give to maize the following year will reward you for the care.

A cowpea calendar for the north and the transition

Use this as a sequence for an early cowpea crop in the north. Early varieties need their pods filled before the dry air returns, so count back from the end of the rains rather than forward from the first shower.

The minor season in the south runs on a different clock, so get your dates from the district office before you plant.

A checklist before the seed goes in

Walk the field with the seed bag in your hand and go through this list. Most of the problems that show up in a cowpea field in August were visible in May, if somebody had looked.

• Match the variety's duration to how long your rains last.
• Check the germination of the seed, and keep a labelled sample of it.
• Check whether a suitable rhizobium product is available for the seed.
• Note the rotation history, and whether cowpea or groundnut grew there recently.
• Mark any hollows or low ground, and move the crop away from them.
• Write the first two weeding dates on the calendar and name who will do them.
• Set a weekly scouting day for flowers and pods, and write down what you find.
• Clean and check the store, and prepare airtight bags before the harvest.

Keep the list with your seed records, and review it after the harvest.

Who to ask before the seed goes in

Ask your district agric officer first for the cowpea varieties recommended this season, and ask whether a rhizobium inoculant is being supplied locally. The answer to the second question changes how you handle the seed on sowing day.

CSIR-SARI at Nyankpala is the research voice for savanna legumes. If a dealer offers you a variety, ask which trial it came from. Traders can tell you which seed colour and size sell in your market, and that conversation is often worth more than a catalogue page.

Planting for Food and Jobs may reach legume growers in some districts. The terms are set locally, so ask the office directly instead of relying on a neighbour's version of what was offered last year.

For credit, the district assembly and rural banks are the first stops, and GIRSAL is the body that backs the risk-sharing behind many agricultural loans. Cowpea is a short crop, so repayment can fall within the same year, provided the grain is dried and sold before the weevils reach it.

A small farm can run cowpea and a flock side by side. Processed grain can go into the birds' ration in measured amounts, and the manure returns to the rotation. Our breeds page sets out the common types, and the order form or a WhatsApp message to +233 24 915 1503 will get your order moving.

If rice or sorghum also sits in your rotation, our rice guide and our sorghum and millet guide cover them in detail.

Questions farmers ask