Groundnut (Revised)

General Information and Agronomic AspectsIntroduction 

rachis hypogaea, commonly known as the peanut or groundnut, belongs to the family Fabaceae and the genus Arachis. The genus Arachis comprises about 70-80 species. A. hypogaea is the most economically significant species in the genus. Other species like Arachis villosulicarpa and Arachis stenosperma have also been grown for their seeds.
A. hypogaea is believed to have originated in South America, particularly in the regions that now encompass Brazil, Bolivia, and Paraguay. Today, peanuts are widely cultivated in various regions, including North and South America, Africa, Asia, and Australia mainly for their edible seeds. Peanuts are well-adapted to a range of environments, thriving in warm temperatures with fertile, light-textured, sandy, well-drained soils. They are often grown as annual plants, as they complete their life cycle in a single growing season. 

Peanuts are an essential food source for many cultures around the world. The seeds or kernels are consumed in various forms, including roasted, boiled, and ground into peanut butter. Additionally, peanuts are made into confectionery and snack foods, and are used as an ingredient for soups or made into sauces to use on meat and rice dishes. Peanuts are highly nutritious and provide a good balance of essential nutrients. The seeds are rich in oil (38-50%), protein, dietary fiber, vitamins (such as niacin, folate, and vitamin E), and minerals (including magnesium, phosphorus, and potassium). Groundnuts have also considerable medicinal value. They are reported to be useful in the treatment of disease such as haemophilia, stomatitis, and diarrhea.

Beyond food consumption, peanuts are also crushed for oil that has both culinary and industrial applications. The press cake from oil extraction is feed rich in protein and is also used to produce groundnut flour, which is used in many human foods. Peanut shells are used for animal feed, and the residual meal after oil extraction can be used for livestock feed. The plant's ability to fix nitrogen makes it an important rotational crop in sustainable agricultural systems.
The global peanut market is substantial, with China, India, and the United States being among the key commercial producers. In Africa, countries such as Nigeria, Senegal, and Sudan are major peanut producers, contributing significantly to the continent's agricultural economy.
(Ntare, B.R., 2007, Plantvillage (n.d.), Carvalho, P. A et al., 2020, Nwokolo, E, 1996).

Species account

Arachis hypogaea is an annual plant with erect or prostrate stems up to 70cm long. Leaves: 4-foliolate with obovate to elliptic leaflets, arranged in alternate. Flowers: axillary, solitary on stalks, yellow, orange, cream, or white flowers which produce 'pegs', characteristic floral structures which sink into the ground to grow the pod. Fruits: pod 3-7 cm long with one to five seeds that develops underground. 
The plant can reach 0.6 m in height depending on the variety and as an annual plant, survives only one growing season.
(Plantvillage (n.d.), Hyde, M.A., et al., 2023).

Groundnuts varieties 
All the varieties of groundnut can be divided into two main subcategories namely; 
Bunch variety These varieties are erect or bunch type with light green foliage, Pods are produced in clusters. Seeds are round, plump and light rose in color. Varieties are early maturing (90 to 100 days) and high yielding and almost free from dormancy with a high germination percentage (90-95). Varieties are small, tastier and a highly marketable variety.
Examples of this variety are Ah.32, Junagadh-II, GAUG-1, Kadiri-71.1, TMV-2, pol.1. pol.2, AK.12-24, Kopergoan-3 etc.
Spreading (Runner type) varieties completely trail along the surface of soil. Plants have dark green foliage. Seeds are oblong and dormant. Long duration (110-120 days), late maturity120 to 150 days (require a longer growing season), high yielding ability and have dormancy (60-75%), low germination per cent (85-90). Some examples of spreading varieties are Punjab-I, Ah.334, GAUG-2, TMV-3, Karad 4-11, M-145, M-13 etc. 
(TIMEIS. (n.d.), ICAR (https://kvk.icar.gov.in/API/Content/PPupload/k0447_28.pdf)
Across Africa, groundnuts exhibit a fascinating range of variations that reflect their diverse origins and breeding endeavors. Peanuts can vary in size from small and bite-sized or plump and oval, with colors spanning from creamy white to deep red. Their flavors vary too, from buttery and mellow to robust and nutty. Different regions have bestowed them with local names, often rooted in the distinct qualities of the plants. These names frequently highlight attributes like seed color and size. 

 

Table: Groundnut varieties and mean kernel yield

Variety	Mean kernel yield Kg/ha
"Red Valencia"	1500
"Severe 116" (white)	1250
"Texas Peanut"	1360
"Bukene"	1530
"Manipintar"	2450
"Makulu Red"	2720
"Altika"	900
"Homa Bay"	770
"Asirya Mwitunde"	1300

 

Ecological conditions

Groundnuts are grown in the warm tropics and subtropics below 1500 m above sea level, and in temperate humid regions with sufficiently long warm summers. Optimum mean daily temperature to grow is 30degC and growth ceases at 15degC. Cool temperatures delay flowering. Groundnuts cannot stand frost. Between 500 and 600 mm of water reasonably well distributed through the growing season allows a good production. Nevertheless, groundnuts are a drought-tolerant species and can withstand severe lack of water, but yield is generally reduced. If harvesting conditions are wet, aflatoxins (severe poison produced by some fungi such as Aspergillus spp. may develop on the nuts. Aflatoxin contamination is a major hazard to human and animal health. When thee groundnuts are poorly dried and stored, they pick mold and dirt, which attracts a fungi, that releases aflotoxin chemicals that are dangerous to human health especially the liver.
Because pods develop underground and must be recovered at harvest, crumbly, well-drained soils are preferred, but plants grow and develop adequately on heavier clay soils. For optimum growth, soil pH should be in the range 5.5 to 6.5, though Bunch types tolerate more acid conditions (pH 4.5) and some cultivars grow well in alkaline soils up to pH 8.5. 

Agronomic aspects

Groundnuts are typically grown from seeds, although it's also feasible to use cuttings for vegetative propagation. These seeds can either be grown in a nursery and then moved to the main area, or they can be directly sown in the main field. Since the seeds are delicate and easily damaged, careful handling is necessary. It's crucial to remember that seeds with splits or damage won't sprout, so top-quality seeds are essential. These seeds should have dried naturally, but if that's not an option, artificially conditioned seeds can be used. However, excessive heat during drying can harm their ability to germinae. Sun-dried seeds are also not recommended for good germination (TIMEIS. (n.d.), Ntare, B.R., 2007)
Planting
Ideally the seedbed should be deep and friable with an even particle size. Take care that the seedbed is weed-free. Cloddy and uneven seed beds can result in uneven emergence and heavy losses of plants. Recommended plant densities are near 200,000 to 250,000 plants/ha for the typically short-season Bunch cultivars. In most countries, cultivation is in rows with plant spacing ranging from 40 x 20 cm to 30 x 20 cm.
After ploughing and harrowing to a fairly good tilth, ridges, which are 80 cm apart with flattish tops, should be made so that two rows of nuts can be planted on each ridge. Seeds for planting should be well selected: they should be clean, well filled and without any blemishes. Seeds for planting should be kept in their pods and shelled a few days before planting. Planting depth is like maize about 5 to 8 cm. Seed rate is 40 to 50 kg/ha depending on the size of the seeds. With good husbandry current farmers' yields of between 450-700 kg/ha could be doubled. 

Intercropping
Groundnuts are grown as a sole crop and also intercropped with maize, soybean and cassava. It is also a good intercrop for upland rice, sorghum, okra, sugarcane, and sunflower. To get a good yield however, proper planting distance should be observed along with the other recommended cultural practices. In some areas, they are grown under perennial tree crops such as coconut, oil palm or rubber. Groundnuts when used as intercrop for upland maize and planted along the contour reduce soil runoff. The plant also reduces population of African bollworm because it serves as a hiding place for beneficial insects. (OISAT) There is an increase in the yield of groundnuts when intercropped with early maturing pigeon pea.

Husbandry
To achieve maximum economic yields, weeds must be eliminated. Groundnuts are very poor competitors with weeds during early stages of growth. Weeding should be done early while at the same time earthing up the ridges to encourage "pegging" i.e. young nuts penetration through the soil. Once pegging has started, only hand weeding should be undertaken to avoid disturbing the young nuts or damaging the flowers. Clean weeding should be done up to 6 weeks after which hand weeding should take over. 
The only peculiar nutrient requirement is for calcium (Ca) in the podding zone. Calcium is absorbed directly by the pods, if soil moisture is adequate. A shortage of Ca in that zone will result in empty pods (especially in Runner cultivars). The crop's needs for nitrogen should be satisfied with symbiotic fixation by strains of Rhizobium of the cowpea group, so nitrogen fertilizers are not generally required. In some areas of acid soils, lime is applied to raise the pH and supply Ca. Moisture stress during flowering or pod filling reduces yield so that irrigation during those periods to minimise or eliminate the stress increases production and seed quality. Where yields are unsatisfactory (heavily eroded soils) an application of 200 kg/ha of rock phosphate is recommended.

Harvest, post-harvest practices and markets

Harvesting
Bunch cultivars are harvested 85-100 days after sowing and Runner cultivars 110-130 days after sowing in the warm tropics. Dig a few plants up to see if the nuts are ready. The nuts should be brown on the outside, firm and dry. Usually at maturity the inside of the pods is grey and some rattling occurs when pods are shaken. Severe disease of foliage sometimes results in harvesting before seeds are fully mature.
Plants should be carefully dug out to avoid nuts breaking off and remaining in the ground. 

Post-harvest practices.
Dry the groundnuts for 2-3 days, then rip the pods from the bushes and place them on mats to dry for another 7-10 days to about 10% moisture. Shelling should be done by hand. Broken, dirty or damaged nuts should be discarded as these will lower the quality and hence the selling price. When the groundnuts are poorly dried and stored, they pick mold and dirt, which attracts fungi, that releases aflatoxin chemicals that are dangerous to human health especially the liver. Nuts to be used as seed the following year should not be shelled.

Markets 

Top peanut producers globally include China, India, the United States, and Argentina. In Africa, Nigeria, Senegal, and Sudan play key roles. China leads the world in peanut production, contributing about 40% of the total. China and India are the biggest peanut consumers and exporters, making up over 36% of global consumption.
The increasing demand for protein-rich foods is set to fuel global peanut demand, leading to increased exports. Additionally, the demand for peanut oil in pharmaceuticals and personal care is boosting the market. Major peanut exporters are Argentina, India, the United States, and China. According to the ITC trade map, in 2021, Argentina exported 634,080 metric tons of peanuts, followed by India with 563,268 metric tons. In the US, peanut production is concentrated in the Southeast, Southwest, Virginia, and North Carolina, which are the primary export hubs (mordorintelligence, 2023, Ntare, B.R., 2007.)

Nutritional value and recipes

Groundnuts, also known as peanuts, are a nutrient-dense source of sustenance. Groundnuts are a noteworthy source of plant-based protein, contributing to muscle repair and growth, as well as overall body function. Peanuts have a low carbohydrate content, comprising just around 13-16% of their total weight. With their high protein, fat, and fiber content, peanuts possess a low glycemic index (GI). This characteristic, indicating a slower carb absorption after meals, renders them a suitable choice for individuals with diabetes.
Moreover, they contain a spectrum of vitamins and minerals, including biotin, niacin, folate, and vitamin E, which collectively support cellular health, metabolism, and immune function. The presence of mono- and polyunsaturated fats, which is predominantly made up of oleic and linoleic acid, lends heart-protective benefits by positively impacting cholesterol levels. Groundnuts also supply an array of antioxidants, such as resveratrol, further contributing to cardiovascular well-being. 
Caution: The primary proteins found in peanuts, namely arachin and conarachin, can trigger severe allergic reactions in certain individuals, potentially leading to life-threatening responses.
For more information: (healthline (n.d). https://www.healthline.com/nutrition/foods/peanuts#carbs, 

Table 1: Proximate nutritional value of groundnuts 100 g edible portion

Code Food Name	Groundnut. shelled. dried. Raw h	Peanut oil a	Peanut butter a	Groundnut sauce a	Recommended daily allowance (approx.) for adults a
Edible conversion factor	1	1	1
Energy (kJ)	2 380	3700	2450	1240	9623
Energy (kcal)	574	900	593	298	2300
Water (g)	5.4	0	5.9	50.2	2000-3000c
Protein (g)	22.4	0	20.1	10.6	50
Fat (g)	44.2	100	48.4	23.4	<30 (male), <20 (female)b
Carbohydrate available (g)	17.4	0	15	9.6	225 -325g
Fibre (g)	8.3	0	8.3	3.5	30d
Ash (g)	2.2	0	2.3	2.7
Minerals
Ca (mg)	45	0	117	132	800
Fe (mg)	3.5	0.1	5.5	2.3	14
Mg (mg)	200	1	225	101	300
P (mg)	445	3	232	209	800
K (mg)	619	0	630	366	4,700f
Na (mg)	6	0	1	492	<2300e
Zn (mg)	2.61	0.1	2.24	1.2	15
Se (mcg)		0	12	7	30
Cu(mg)	0.79
Bioctive compounds.
Vit A RAE (mcg)	4	0	0	28	800
Vit A RE (mcg)	2	0	1	28	800
Retinol (mcg)	0	0	0	28	1000
b-carotene equivalent (mcg)	23	0	4	2	600 – 1500g
Thiamin (mg)	0.87	0	0.85	0.28	1.4
Riboflavin (mg)	0.14	0	0.14	0.21	1.6
Niacin (mg)	15	0	15	5	18
Dietary Folate Eq. (mcg)	110	0	110	27	400f
Food folate (mcg)	110	0	110	27	400f
Vit B12 (mg)	0	0	0	0.17	3
Vit C (mg)	1	0	0	0	60

Source (Nutrient data): FAO/Government of Kenya. 2018. Kenya Food Composition Tables. Nairobi, 254 pp. http://www.fao.org/3/I9120EN/i9120en.pdf

RE=retinol equivalents.

RAE =Retinol activity equivalents. A RAE is defined as 1μg all-trans-retinol, 12μg beta-carotene, or 24μg α-carotene or β-cryptoxanthin.

^a Lewis, J. 2019. Codex nutrient reference values. Rome. FAO and WHO

^b NHS (refers to saturated fat)

^c https://www.hsph.harvard.edu/nutritionsource/water/

^d British Heart Foundation

^e FDA

^f NIH

^g Mayo Clinic

^h- FAO/INFOODS Food Composition Table or Western Africa (2019) https://www.fao.org/3/ca7779b/CA7779B.PDF

Recipes

1. Kisamvu na njugu (Cassava leaves with groundnuts)
(Nyamwezi, Tabora, Tanzania)

Ingredients 

• 4 handfuls of Kisamvu (Cassava leaves)
• ¼ cup, groundnut sauce
• Tomatoes (3 tomatoes, medium size)
• 2 Onions (medium size)
• (Note: Ratio can be adjusted to one’s taste)

Procedure 

1. Wash cassava leaves
2. Pound the leaves in a mortar
3. Cook for one hour
4. Add groundnut sauce
5. Add tomatoes and onions
6. Let it cook briefly

Served with a starch food such as ugali (stiff porridge)

Preparing the groundnuts
Fry groundnuts
Using kinu (a mortar) and pestle pound the groundnuts
Grind it more with a small mortar or base of a cup to soften it more

2. Uji wa ulezi (Enriched finger millet porridge)
Source: Rangi, Kondoa, Tanzania

Ingredients 

• Mixed flour (enough for desired consistency)
• 1/2 litre of tui bubu or thick coconut milk (or 2 litres of thin coconut milk) 
• 2-3 litres of water (if tui bubu is used)

                     
Preparation of the flour
1. Wash ulezi, maize, groundnuts, rice and dry in air for at least 2 hrs
Add 2 kg ulezi (finger millet)
1 kg maize
1 kg wheat flour
1 kg rice
¼ kg groundnuts
4-5 packets of iliki
2. Grind the mixture to flour 
3. Mix with wheat flour 
4. Take the desired portion of flour (depending on number of people to be served)
5. Put sufuria (metal pot) on fire with water and let it boil 
6. Put the mixed flour in a container, mix with water and stir
7. Pour the mixture in boiling water and stir
8. Let it boil for about 15 minutes
9. Add sugar to taste 
10. Add coconut milk and continue boiling for another 5 minutes
Serve 
Note: The right ratio of water to flour needs a bit of experience but also depends on how thick you want your porridge.

3. Boo and otigo (Cowpea and jute leaves cooked with groundnut paste)
(Source: Acholi, Gulu, Uganda)

Ingredients:

• 4 portions of cow pea leaves (boo)
• 1 portion of Jew’s mallow leaves (otigo)
• Water
• Soda ash
• Salt
• Tomatoes
• Groundnut paste
• Simsim (sesame)

Procedure:

1. Process both, boo and otigo leaves. This involves plucking individual leaves (and leaflets for boo) and discarding all stalks.
2. Clean well
3. Place boo leaves on a chopping board and cut the leaves
4. Place otigo leaves on the chopped boo and chop it as well
5. Boil 1 cup of water (cooking for 2 people)
6. Pour ½ table spoonful of traditional ash filtrate (kado atona /atwona - lye) and bring it to boil.
7. Add the vegetable mixture
8. Cook for about 15 minutes in high fire (up to 30 minutes in low fire)
9. Add salt and then tomatoes and cook till tomatoes are ready
10. Remove from fire
11. Add groundnut paste with simsim and mix. The vegetable must be hot!

Served with: Kwon kal (finger millet stiff porridge), sweet potato, cassava or matoke (cooked banana or plantain)

4. Butuzi (Local mushroom with groundnut)
(Banyoro, Kibaale, Uganda)

Ingredients: 

• 2 handfuls of mushrooms
• Groundnut paste
• Water
• Salt

Procedure:

1. Chop the mushrooms
2. Soak for 5 minutes
3. Clean with water 
4. Boil mushrooms with 2 cups water
5. Add groundnut paste
6. Cook for 10 minutes and add salt

Served with: 
-    Banana / plantain
-    Finger millet ugali

5. Enyobwo sauce (Bean sauce with groundnuts)
(Source: Banyoro, Hoima, Uganda)

Ingredients: 

• Beans
• Water
• Salt
• Groundnuts paste 
• Curry powder

Procedure:

1. Beans are boiled in water until they are soft
2. Groundnut paste is added
3. Salt and curry powder are also added to make a sauce known as Enyobwo.

Served with: Starchy foods

6. Ebinyebwa (ground nut sauce) 

(Source: Baganda, Wakiso, Uganda)

Ingredients: 

• Groundnut flour or paste
• Water
• Salt
• Onions

Procedure:

1. Grind groundnuts to flour or paste 
2. Mix with moderate water
3. Add onions 
4. Cook on fire till the mixture stops foaming

 
Served with: 
Matooke, Cassava, boiled sweet potatoes

Note: The groundnuts with onions can also be put in a metallic saucepan with close fitting lid and cooked  (steamed) together with the matooke

7. Eboo ((cowpea leaves)
(Source: Teso, Soroti, Uganda)

District and region: Soroti

Ingredients:

• Eboo (4 heaps or handfuls)
• Water
• Abalang (lye, traditional salt)
• Salt
• Groundnut (Emaido)

Procedure:

1. Prepare 4 handfuls of Eboo
2. Boil little water ½ cup (enough for four handfuls of cowpea leaves)
3. Add 4 table spoonfuls (about 40 ml) of abalang (lye) 
4. Wash the leaves 
5. Chop leaves or leave them intact
6. Put leaves in boiling water
7. Let leaves boil for 20-30 minutes
8. Check if cooked (soft). Can add more abalang if not cooked and boil a bit more

Serve when cooked.

Served with: 
Atap (stiff porridge) or boiled sweet potatoes (Acok nu idoritai)

Note: You can mix Atigo (Jute mallow) with Eboo (Cowpea) leaves before cooking in the ratio of ½ heap of Corchorus: 4 heaps of Eboo. The rest of procedure is same. Eboo prepared with atigo is slippery. Atigo makes the vegetable soft.

Climatic conditions, soil and water management

Groundnuts are grown in the warm tropics and subtropics below 1500 m above sea level, and in temperate humid regions with sufficiently long warm summers. Optimum mean daily temperature to grow is 30°C and growth ceases at 15°C. Cool temperatures delay flowering. Groundnuts cannot stand frost. Between 500 and 600 mm of water reasonably well distributed through the growing season allows a good production. Nevertheless, groundnuts are a drought-tolerant species and can withstand severe lack of water, but yield is generally reduced. If harvesting conditions are wet, aflatoxins (severe poison produced by some fungi such as Aspergillus spp. may develop on the nuts. Aflatoxin contamination is a major hazard to human and animal health. When thee groundnuts are poorly dried and stored, they pick mold and dirt, which attracts a fungi, that releases aflotoxin chemicals that are dangerous to human health especially the liver.

Because pods develop underground and must be recovered at harvest, crumbly, well-drained soils are preferred, but plants grow and develop adequately on heavier clay soils. For optimum growth, soil pH should be in the range 5.5 to 6.5, though Bunch types tolerate more acid conditions (pH 4.5) and some cultivars grow well in alkaline soils up to pH 8.5. 

Propagation and planting

Ideally the seedbed should be deep and friable with an even particle size. Take care that the seedbed is weed-free. Cloddy and uneven seed beds can result in uneven emergence and heavy losses of plants. Recommended plant densities are near 200,000 to 250,000 plants/ha for the typically short-season Bunch cultivars. In most countries, cultivation is in rows with plant spacing ranging from 40 x 20 cm to 30 x 20 cm.

After ploughing and harrowing to a fairly good tilth, ridges, which are 80 cm apart with flattish tops, should be made so that two rows of nuts can be planted on each ridge. Seeds for planting should be well selected: they should be clean, well filled and without any blemishes. Seeds for planting should be kept in their pods and shelled a few days before planting. Planting depth is like maize about 5 to 8 cm. Seed rate is 40 to 50 kg/ha depending on the size of the seeds. There are 2 types of groundnuts: 

• Bunch type
• Runner type

Bunch varieties such as Red Valencia mature within 90 to 100 days, while runner types such as "Homa Bay" mature in 120 to 150 days (require a longer growing season).

Table: Groundnut varieties and mean kernel yield

 

With good husbandry current farmers' yields of between 450-700 kg/ha could be doubled. 

Intercropping

Groundnuts are grown as a sole crop and also intercropped with maize, soybean and cassava. It is also a good intercrop for upland rice, sorghum, okra, sugarcane, and sunflower. To get a good yield however, proper planting distance should be observed along with the other recommended cultural practices. In some areas, they are grown under perennial tree crops such as coconut, oil palm or rubber. Groundnuts when used as intercrop for upland maize and planted along the contour reduce soil runoff. The plant also reduces population of African bollworm because it serves as a hiding place for beneficial insects. (OISAT) There is an increase in the yield of groundnuts when intercropped with early maturing pigeon pea.  

Husbandry

To achieve maximum economic yields, weeds must be eliminated. Groundnuts are very poor competitors with weeds during early stages of growth. Weeding should be done early while at the same time earthing up the ridges to encourage "pegging" i.e. young nuts penetration through the soil. Once pegging has started, only hand weeding should be undertaken to avoid disturbing the young nuts or damaging the flowers. Clean weeding should be done up to 6 weeks after which hand weeding should take over. 

The only peculiar nutrient requirement is for calcium (Ca) in the podding zone. Calcium is absorbed directly by the pods, if soil moisture is adequate. A shortage of Ca in that zone will result in empty pods (especially in Runner cultivars). The crop's needs for nitrogen should be satisfied with symbiotic fixation by strains of Rhizobium of the cowpea group, so nitrogen fertilisers are not generally required. In some areas of acid soils, lime is applied to raise the pH and supply Ca. Moisture stress during flowering or pod filling reduces yield so that irrigation during those periods to minimise or eliminate the stress increases production and seed quality. Where yields are unsatisfactory (heavily eroded soils) an application of 200 kg/ha of rock phosphate is recommended.  

Harvesting

Bunch cultivars are harvested 85-100 days after sowing and Runner cultivars 110-130 days after sowing in the warm tropics. Dig a few plants up to see if the nuts are ready. The nuts should be brown on the outside, firm and dry. Usually at maturity the inside of the pods is grey and some rattling occurs when pods are shaken. Severe disease of foliage sometimes results in harvesting before seeds are fully mature.

Plants should be carefully dug out to avoid nuts breaking off and remaining in the ground. Dry for 2-3 days, then rip the pods from the bushes and place them on mats to dry for another 7-10 days to about 10% moisture. 

Shelling should be done by hand. Broken, dirty or damaged nuts should be discarded as these will lower the quality and hence the selling price. When thee groundnuts are poorly dried and stored, they pick mold and dirt, which attracts a fungi, that releases aflotoxin chemicals that are dangerous to human health especially the liver. Nuts to be used as seed the following year should not be shelled.