OVERALL OBJECTIVE
Assessing the production levels of oil crops in Botswana
SPECIFIC OBJECTIVES
- To assess the production level of groundnuts in farming regions of Botswana.
- To compare the production levels of traditional and commercial farming systems of Botswana.
INTRODUCTION
The groundnut (Arachis hypogeae L.) originated in South Bolivia and North Western Argentina is grown as an annual crop in warmer regions of the world including Botswana, principally for its edible oil and protein rich seeds (42-51 % oil and 40-50% protein) (Protabase 2009). In most tropical and subtropical areas where groundnut is grown, the climate is seasonally arid and the staple crop is a cereal usually maize. To ensure survival farmers plant the cereal as soon as they can when the rains start and only plant groundnuts when cereals have established (Summerfields and Roberts 1985). Groundnuts are usually grown by poor smallholder farmers and are considered a women’s crop thus it is given lesser priority for when it comes to inputs such as certified seed fertilisers and irrigation (Okumu 1999).
WHY GROW GROUNDNUTS
- Chief source of edible oils and plant protein in human diet.
- Low input-high value crop.
- Cost of production drawn from purchasing seed but farmers can preserve seed from previous crop unlike most crops.
- Most costs in groundnut production are labour and can be supplied by family in scarcity of cash (Finn and Kenny 2004).
- Groundnut is an income substitute or supplement for maize.
- Unlike vegetables and fruits which are highly perishable items, groundnuts can be stored for a long period of time and sold when prices are high.
- Farmers can also double its price by roasting it hence earning even higher income.
- Since groundnut takes a shorter time to mature, the land can be used for another possible cropping thus utilising the second rains. This increases gross margins per unit area of land per year.
- Groundnuts are nitrogen fixers and so improve soil fertility ( Okumu, 1999).
CLIMATIC AND SOIL REQUIREMENTS
Groundnut requires warm tropical and subtropical environments and is well adapted to sandy and sandy loam soils. The optimum mean daily temperature for Botswana is 27-30˚c, optimum soil temperature for seed germination is 25-30˚c and temperatures lower than 20˚c slows development and those higher than 35˚c adversely affect development. A rainfall range of 500- 1000mm is ideal for groundnut production but a crop can produce on as little as 300-400mm thus it has some degree of drought tolerance. A dry period is required for ripening and harvesting and a soil pH of 5,8-6,2 is ideal for production (Tsuaneng and Maphanyane 2000).
LAND PREPARATION
Groundnuts should be sown in a seedbed with a fine tilth since large clods may hamper emergence. Due to its pod forming habit, deep ploughing should be avoided since it encourages development of pods in deeper layers of the soil making harvesting difficult (Bass, 2000).
SELECTION AND TREATMENT OF SEED
Quality seeds are of utmost importance for establishing the optimum plant stand. Pods for seed purposes should be stored unshelled in a cool dry and ventilated place and pods should be shelled by hand one week before sowing as hand shelling ensures little damage to the seeds. Seeds shelled before sowing times are liable to suffer from loss of viability and storage damages. Shrivelled and diseased seeds should be discarded and only bold large seeds should be used for sowing (Bass 2000). Seeds should be treated with thiram or captan before sowing to check various seed and soil borne diseases. Seeds should also be inoculated with a proper strain of rhizobium culture particularly in those places where groundnut is grown for the first time ( Tsuaneng and Maphanyane 2000).
PLANTING
In Botswana groundnuts should be sown from late November to mid December and soil moisture reserves are often adequate at this time to sustain good vegetative development and produce strong plants. Planting later than the end of December often exposes the crop to good moisture reserves but mid season drought usually experienced in January can affect pod formation and filling. The season also becomes too short to allow enough time for maturity. Planting in November exposes the crop to risks of early season drought. Low temperatures at this time also adversely affect germination resulting in poor or delayed emergence. Groundnuts in Botswana are planted 4-6cm deep at a rate of 30kg/ha for row planting (Tsuaneng and Maphanyane 2000) but in other places it is planted 4-7 cm deep in moist soil at a rate of 60-80kg/ha (Protabase 2009).
PLANT POPULATION
The recommended plant population in Botswana is 50-100 000 plants/ha depending on moisture availability and 133 000 plants/ha under irrigation. An inter row spacing of 0.75m is recommended with variation of 0.1-0.2m within row depending on plant population required (Tsuaneng and Maphanyane 2000). In other places optimum plant populations are 133 000 to 167 000 and Spanish types are spaced at 60-75cm between rows and 10cm within rows while large seeded Virginia types are spaced at 75cm between rows and 15cm within rows giving a plant population of 89 000 plants/ha (Summerfield and Roberts 1985).
CULTIVARS
The recommended groundnut varieties in Botswana are given in the table below
Cultivar | Growth habit | Maturiy (Days) | Yield (t/ha) | Seed | Pod | ||||
colour | size | Size (mm) | Beak | Constriction | Reticulation | ||||
Sellie | Upright | 120-130 | 1-2 | Tan | Medium | 26 | Slight | Moderate | Prominent |
GC8-13 | Upright | 115 | 1-2 | Tan | Small | 25 | Moderate | Slight | Prominent |
S46 | Prostate | 120-130 | 1-2.5 | Tan | Small | 30 | Slight | Deep | Slight |
ICGS-31 | upright | 120-130 | 1-2.5 | Tan | Small | 25 | Absent | Slight | Moderate |
(Tsuaneng and Maphanyane 2000).
FERTILISATION
Groundnuts meet major part of its Nitrogen requirement through nitrogen fixation. However an application of 20-40kg/ha as a starter dose is given to meet the nitrogen requirement of the crop in the initial stage in poor fertility soils. About 50-60kg P2O5 and about 30-40kg K2O/ha should also be added (Wyne and Rowe 1998). In Botswana a basal application of N, P and K at 23; 10.5; and 12.5 kg/ha respectively, benefits the crop by improving plant establishment and pod production. Calcium is an important element for pod development and filling and should be applied as gypsum at 500kg/ha at flowering. Farmyard manure/compost can also be added at 10-15t/ha before sowing (Tsuaneng and Maphanyane 2000).
MANAGEMENT PRACTICES
Weeding should be done thoroughly at the early vegetative stage and 1 or 2 hoeings should be done depending on soil type and extend of weed infestation. Earthing up (hilling) should also be done to promote easy penetration of pegs in soil and also provide more area to spread. To control diseases, plant debris should be buried or burnt and infected plants should be rouged as soon as they appear in the field. Tolerant cultivars should be grown and insecticides should be used to control high incidence of pests. Groundnut can also be intercropped with maize, millets, sorghum, and sunflower (Finn and Kenny 2004).
PESTS AND DISEASEAS
Groundnut is attacked by various pests and diseases and some of the pests include thrips, aphids, groundnut leafminer, termites, and maize rootworm. Diseases include early leaf spot, rust while viruses include groundnut rosette virus which is transmitted by aphids. Aspergillus fungi also attack pods and seeds producing alfatoxin (Summerfields and Roberts 1985).
HARVESTING AND STORAGE
Groundnuts should be harvested when mature because premature harvesting lowers yield and kernel quality. The plants should not be allowed to dry before harvesting as this tends leads to pod losses at harvesting. To determine maturity, scratching the groundnut pod from outside will show a dark brown colour for a mature pod while a cream white colour is indicative of immaturity. Mature pods also show brown to dark marks on the inside while immature pods are white and pulpy or fibrous (Tsuaneng and Maphanyane 2000). Groundnuts should be harvested in dry weather to avoid rotting and development of mould due to wet weather. Harvesting is done by hand or by machines using a digger shaker inverter. The plants should then be stoked to dry before threshing. Threshing is done by hand or machine when plants are dry and pods should be stored in stacked bags until required (Bass, 2000).
USES
- The seed is eaten raw, boiled or roasted and is made into peanut butter and oil is also extracted from the seed.
- After oil extraction the press cake which is high in protein is used as animal feed, makes flour, glue, starches and wool.
- Shells are used to make building blocks and are a source of reducing sugars, organic chemicals, combustable gas, activated carbon and are also used for livestock feed.
- Plants may be used to feed animals as fodder or silage.
- Young pods and leaves are consumed as vegetables in some parts of West Africa and pod extracts are used for medicinal purposes like as eyedrops to treat conjuctivis and also have aphrodisiac properties. Macerations of seed coats treat syphyllis and ophthalmia and leaf infusions treat female infertility and eye injuries and cataracts.
- The groundnut plant fixes nitrogen and so improves soil fertility and the haulms are applied as green manure and shells are used as fertiliser or mulch (Protabase 2009)
Groundnut yield in kg/ha per region
Region | Year | |||||||||
1989 | 1990 | 1993 | 1995 | 1996 | 1997 | 1998 | 1999 | 2001 | 2002 | |
Southern | 57 | 200 | 196 | - | 342 | 127 | 56 | 18 | - | 157 |
Gaborone | 250 | 250 | - | 2033 | 191 | 90 | 54 | - | 22 | 16 |
Central | 250 | 100 | 10 | 1352 | 115 | 224 | 24 | 4 | 73 | 36 |
Francistown | - | - | 90 | 382 | - | 173 | 8 | 191 | 114 | 46 |
Maun | - | - | 1364 | - | - | - | - | - | 35 | 195 |
Western | - | - | - | - | - | - | - | - | 17667 | - |
Traditional | 108 | 100 | 64 | 856 | 240 | 193 | 10 | 73 | 100 | 64 |
Commercial | 500 | 500 | 193 | 200 | - | 143 | 16 | - | - | 630 |
Total | 232 | 233 | 79 | 853 | 240 | 193 | 11 | 72 | 100 | 72 |
DISCUSSION
The average yield (kg/ha) of groundnuts was very low from 1989 to 1993 and this may have been because of poor rains which are usually received in Botswana. The yield then increased from 1993 to 95 especially in Maun, Central and Gaborone regions with Maun reaching its peak in 1993 and Central and Gaborone regions reaching theirs in 1995. This maybe because there was a lot of rain in the 1995 season. There was however a deterioration in yield after reaching the peak up to 1999 but it started increasing again in 2001 up to 2002 though at a slower rate. This may be because the conditions of poor rains had started prevailing again.
The average total yield of groundnut was constant in 1989 and 90 and increased to reach a peak of just above 800kg/ha in 1995 coinciding with the year in which there was an increase in yield in Gaborone and Central regions. The total yield started declining in the subsequent years to levels below 300kg/ha.
Commercial yield showed constant yield in the first 2 years and declined to 200kg/ha and below only to increase sharply and reaching a maximum of above 600kg/ha in 2002. Traditional yield was more or less constant averaging around 100kg/ha from 1989 to 93 and sharply increased to a maximum of above 800kg/ha in 1995 before declining in the subsequent years to levels below 200kg/ha. The decrease may have been due to drought conditions prevailing again since there may have been more rain in 1995 which had caused a sharp increase. However the commercial farming system generally has higher yields than traditional and this maybe mainly because of use of improved hybrids, fertiliser, more weed and pest control and maybe supplementary irrigation.
CONCLUSION
Yields of oil crops are consistently low in all farming regions as they are below the expected Botswana yields and this is probably due to poor rains and substandard management. The subsistence farmers are getting lesser yields as compared to the commercial farmers and most of these small scale farmers who are growing oil seed crops have limited access to resources and markets. Most of them cannot at present afford expensive capital developments or purchased inputs. The physical, financial, technical, commercial and administrative support which farmers in the industrialised countries are getting is not mostly available to them. However significant improvements are already technically possible as new cultivars with durable and stable resistances, tolerances and adaptations to biological and environmental constraints have been and are being developed. Establishment of local industries that use oil crops as raw materials can also help to provide market for the oil crops produce and thus gives farmers an incentive for spending more on inputs and thus produce more.
RECOMMENDATIONS
The market demand should be sustained so that an efficient and reliable seed industry can deliver improved seeds to farmers. Farmers should also purchase seed from reputable seed companies or dealers with a good technical service record if production problems do occur and assistance or consultation is required. The cultivars which the seed companies must offer should provide a measure of insurance against pests, diseases and drought and this would encourage both small scale farmers and large scale farmers who are entering agriculture to use more productive methods including timely sowing and control of weeds to ensure higher productivity. The farmers should always seek for assistance from the nearest offices of the Department of Agriculture.
REFERENCES
Bass M.H. 2000. Groundnut: Production guideline: www.ficciagroindia.com. Agribusiness information centre.
Finn K and Kenny A. 2004. Groundnuts, women and development.
Okumu M.O. 1999. Economic evaluation of groundnut for smallholder farmers. Ministry of Agriculture and Rural development, Kenya.
Summerfield R.J and Roberts E.H. 1985. Grain legume crops. Cpllins Professional and Technical Press.
Tsuaneng M.M and Maphanyane G.S. 2000. Field crops reference Handbook in Botswana Department of Agriculture Research.
Van de Vossen H.A.M and Fagbayide J.A. 2007. Helianthussannus L. Plant Resources of Tropical Africa. http://database.protabase.org. Accessed 17th April 2009.
10. Wynne J.C and Rowe R.C. 1998. Advances in Agronomy.
