INTERNATIONAL POTATO CENTER: WORLD SWEETPOTATO ATLAS
MOZAMBIQUE
HISTORY AND OVERVIEW
The sweetpotato, Ipomoea batatas, preceded the potato, Solanum tuberosum, in its diffusion beyond the American tropics, where it was widely grown in pre-Columbian times. Columbus brought sweetpotato with him on his return to Spain from his first voyage in 1492, eighty years before the potato reached Europe (Purseglove 1968, p. 81). By the 1520s, Portuguese mariners were carrying sweetpotato to ports and territories throughout Africa and Asia, a diffusion later continued by other Europeans (Huntington). The subsequent historical record is somewhat unclear since the term "potato" was derived from "batata" (the Carib term for sweetpotato), so that historical documents from this era could be referring to either crop, both of which have become significant to Mozambique.
Sweetpotato has become well established in Mozambique, and in many other relatively humid areas of equatorial Africa, due to its high yield relative to both land and labor, its capacity to grow in relatively poor soils, and its high content of carbohydrates and vitamins, especially vitamin A. Sweetpotato can produce more energy per land area and over time than rice or cassava, two of Mozambique's major staple crops. (Maize is the predominant staple crop in most regions.) Sweetpotato is regularly consumed by approximately half of the rural population, and is a particularly important source of food in the dry season (Henderson et. al. 1997).
The current role of sweetpotato, and more generally the status of agriculture in Mozambique, can only be understood in light of tremendous disruptions over the past several decades. Mozambique gained its independence from Portugal in 1975 following several years of armed conflict. In response to nationalist rebels of the Zimbabwe African National Union (ZANU) based in Mozambique, Rhodesian forces invaded in 1979 and caused many civilian casualties and tremendous damage. South Africa subsequently supported a dissident group, the Mozambique National Resistance Movement (MNR, or Renamo) which fought the government in a civil war lasting until 1992, at times controlling or threatening most rural areas (Columbia 2003). By 1992, approximately 1.7 million Mozambican refugees (roughly ten percent of the population) were in the process of returning home when the country suffered one of the worst droughts of the century. In February and March of 2000, a devastating cyclone flooded the Limpopo and Changane River valleys in the southern region, causing severe losses of livestock and crops over an area of 150,000 hectares, and displacing over 500,000 people (IIASA 2001). In some areas of the country, people are still displaced due to tens of thousands of unexploded landmines from the civil war. The areas most affected by mines are generally those of potentially high population density and agricultural productivity (ICBL 2001).
In spite of the enormous challenges facing the country, longer-term agricultural potential in Mozambique is promising. Estimates of arable land vary, but according to the United Nations Food and Agriculture Organization (FAO), the total area of land devoted to arable and permanent crops (just under 45,000 square kilometers) is less than ten percent of the total potential agricultural area of over 480,000 square kilometers (FAOSTAT). Agriculture is essential to the Mozambican economy, employing more than eighty percent of the labor force and contributing approximately twenty-four percent of the gross domestic product (IISA; UK Trade and Investment). Agricultural production is primarily subsistence-based with very little use of chemical or mechanical inputs, and as in much of sub-Saharan Africa, women bear the responsibility for essential tasks such as land preparation, weeding, harvesting, transportation, storage, and marketing (IIASA).
According to FAO data for 2004, sweetpotato is cultivated on 9,000 hectares in Mozambique (FAOSTAT). Although it is impossible to determine precise figures for production by area or yield, a survey of 5,000 rural households, completed in April 2004, estimated the area of sweetpotato cultivation at 96,515 hectares, over ten times the FAO estimate (personal communication, Charles Crissman). Average yields have been estimated at slightly more than seven tons per hectare (T/HA) by FAO, much higher than the estimate of four T/HA reported in the survey noted above. Four T/HA is a fairly typical yield for the region, Angola being the most historically relevant comparison, suggesting high potential to increase food security via further gains in average yields (FAOSTAT).
Sweetpotato is currently being developed as a means to address one of the most serious health and nutrition problems of sub-Saharan Africa, Vitamin A deficiency. Lack of Vitamin A can weaken the immune system, leaving an individual more susceptible to deadly diseases such as measles, malaria, and diarrhea. Vitamin A deficiency is also a leading cause of visual impairment and a major risk factor for pregnant and lactating women. The International Potato Center (CIP) is a major partner of Vitamin A for Africa (VITAA), a project intended to develop and distribute to Mozambique and several countries in sub-Saharan Africa a new series of sweetpotato cultivars which are rich in betacarotenes, used by the body to synthesize Vitamin A. The VITAA project is an example of biofortification, intended to develop crop varieties with increased mineral and vitamin content to enhance nutritional standards. Mozambique, given its current and potential production of sweetpotato and its nutritional needs, could likewise benefit from this initiative.
For more information, please see:
GEOGRAPHY AND PRODUCTION ZONES
Physical Geography and Climate
Mozambique is a large country, of 800,000 square kilometers. Although an abundance of land is available for agriculture, crop production is highly dependent on precipitation which is both spatially and temporally variable. Much of Mozambique can be classified as semi-arid, specially extensive areas to the west and south.
Much of the potential for agricultural development in Mozambique lies with its groundwater resources, including over 100 rivers (several of which originate in neighboring countries). Mozambique also contains many lakes, including a few which are dammed. Part of Lake Malawi, one of the great Rift Valley lakes of Equatorial Africa, is contained within Mozambique. Since most soils are of limited fertility, especially to the south, alluvial soils derived from riverine floodplains are potentially important to agricultural development, but are also ecologically sensitive.
For more information:
- Regarding water resources in Mozambique, please see the FAO report, Wetlands for Agricultural Development
. This document also includes a Climate Zones map. (Please see figure 1.)
- Several images of water resources and structures can be seen at the Water Page, posted by Water Policy International Limited.
- Several maps of more specific classifications — for example by soil types, agro-ecological zones, and land use — are available from the European Digital Archive of Soil Maps, Mozambique. Most images are digitized from paper maps, of variable clarity.
Precipitation is characterized by distinct wet and dry seasons. Approximately eighty percent of total annual rainfall occurs between October and April, although erratic rainfall during these months can cause severe drought. Very little rainfall occurs during the cooler months of May to September. Temperature and humidity are usually higher near the coast due to the warm Mozambique current which flows south from the equator. Rainfall is generally highest (around 1,350 to 1,500 millimeters (mm) annually) in the central coastal region, between Quelimane and Beira. Annual precipitation ranges from an average of 1,000 to 1,400 mm in the Northern Region. Southern Mozambique is the driest region, especially in the rain shadow of the Lebombo Mountains. Mean annual rainfall at the western edge of the Gaza Province is approximately 300 mm (IRRI and CIAT). Precipitation in the south is also annually variable, subject to periods of prolonged drought.
Regional Distribution of Sweetpotato Production
Since sweetpotato production data for Mozambique are tentative in general, estimates of production zones are likewise inconsistent or incomplete. A 1997 report for the South Africa Root Crops Research Network (SARRNET) indicated that main growing areas include Niassa in the north, Sofala in the center, and Gaza in the south (SARRNET 1997). These data are not consistent with more recent survey data, which indicate that sweetpotato cultivation is not highly concentrated in any particular region, though as expected is less cultivated in areas of extremely low precipitation. Crop production in Mozambique is, however, a result of historical as much as physical factors. Events over the past several decades have caused a shift of the population toward the coast, hence a concentration of subsistence agriculture not entirely attributable to physical factors.
(Please note: Given the lack of reliable data on this topic, a map of sweetpotato distribution is not included for Mozambique.)
PRODUCTION SYSTEMS AND CONSTRAINTS
Sweetpotato is frequently overlooked in large part because its cultivation is very decentralized, usually grown in small household plots, typically 150 - 200 square meters (SARRNET 1997). Average yields were reported at four tons per hectare in 1988 and 1992, during and at the conclusion of the civil war (Jimenez et al., 1988; Barreiros et. al. 1992), though average yields are apparently somewhat higher as of 2004 (FAOSTAT).
Vines are normally planted approximately thirty centimeters apart on ridges spaced one meter apart, most often in pure stands. Weeding is usually done once, before the vines are fully established. Harvesting usually occurs four months after planting, sometimes later depending on the variety (SARRNET 1997). Cultivation occurs throughout the year, but mostly between September and February. Where irrigation is possible, for example in the Chokwe Region (Gaza Province near the Limpopo River), a crop is planted twice, in August and February (Jimenex 1988).
Sweetpotato is not reported to suffer much loss from diseases or insect damage, but at least as of 1992, disease and pest infestations of sweetpotato had been studied much less than those of cassava (Jimenex 1988; Barreiros et. al. 1992). There are reports of weevil infestation, the most common species being Cylas formicarius (Fabricius) and Cylas puncticollis Boheman (Apionidae). Alcidodes dentipes (Olivier) (Curculionidae) is also reported to affect stems (Barreiros, et. al. 1992). Viral diseases are widespread, affecting mostly local germplasm and at least one variety introduced by the International Institute of Tropical Agriculture (IITA) (Jimenex 1988). SARRNET reported that extension workers have noticed sweetpotato root and stem weevils and leaf eaters (species not indicated), but that farmers do not regard these pests to be as serious as theft and wandering goats (SARRNET 1997).
VARIETIES AND SEED SYSTEMS
Since sweetpotato readily flowers and sets seed in tropical conditions, many varieties grown in Mozambique are locally selected hybrids. SARRNET has reported that farmers generally favor varieties which provide reliable yields, are early maturing, and sweet tasting (Minde and Jumbe 1997).
In response to the crisis facing the nation during the civil war, and later as refugees returning home were in urgent need of planting materials, the government and several non-government organizations (NGO's) established a rapid multiplication and distribution program, including a tissue culture lab established by1990 (Barreiros 1992). Jimenex (1988) reported that short-term evaluations under local growing conditions (but with irrigation available as needed) identified four newly-introduced varieties with superior yields, but only one (INIA 39, with red skin, white flesh, and low fiber content) meeting other criteria of eating quality, resistance to pests and diseases, and overall high acceptance. Subsequent evaluations over a three-year period (many with fertilizer applications and a high level of management) resulted in preferences for three varieties: INIA 3, INIA 10, and INIA 18. Yields were generally above twenty tons per hectare. Barreiros (1991) reported that improved varieties in the initial distributions included: Inia 18, Tis 234, Tis 2498, Tis 9265, Tis 2532, Clone 7, Tib 9, Inia 39, Malawianna, and Campalendo. No further details are yet available.
In 1997, World Vision International - Mozambique, in collaboration with the National Institute of Agronomic Research, reported evaluations of eight varieties included in trials over three seasons, ending 1993 through 1995. These evaluations were undertaken in parallel with the Emergency Seeds and Tools Distribution Program to determine which varieties of sweetpotato would be best suited to meet the needs of returning refugee families in need of planting materials. A wide range of locations across the Zambézia, Nampula and Tete Provinces in the northern and central regions of the country were included to assess interactions of varieties and agroecological zones. Varieties indicating initial promise were included in more extensive on-farm trials which evaluated each according to early maturity, resistance to insects and diseases, storage quality, palatability, and commercial market acceptability. Any significant variation of varietal performance by agroecological zone was used to guide subsequent distribution efforts. Plants were harvested four and six months after planting to identify relative maturity dates (Henderson et. al. 1997). Varieties included two regional varieties obtained from Zambézia Province (Wadidjela Vagombe and 15 Dias) and six IITA-derived improved varieties: TIS 2534, INIA 18, Clone 3, Clone 7, TIS 2498, and TIS 2532. TIS 2534 was included in all trials, INIA 18 and 15 Dias in eight trials, and the other four varieties in five trials each. (Locational specifics and rationale for selection were not further specified.)
The results of the trials suggest that the interaction of variety and environment is a large factor of sweetpotato production in the rainy season, both over space and time. Best linear unbiased predictors (BLUPs) of yield (tons per hectare) were calculated for all varieties in nine locations over three growing seasons, and separately for each of the eight varieties grown over the three seasons. The only climatic data provided by the study were long-term average rainfall and classification of elevation by midland or lowland. It is possible that highly varied results by region over time could be due to irregular rainfall. For example, the Gurúè area, in Zambézia Province, is characterized by abrupt termination of rains after a short season; yields for all varieties did not increase in the interval from four to six months, obviously factoring against the distribution of longer duration varieties in that area.
Varietal observations included:
- 15 Dias: Highest yielding as estimated by BLUP, and apparently suitable for wide distribution, popular as an early maturing variety which grows quickly over the first four months, also replanted easily as newly planted vines resist drying during the rooting phase;
- Clone 7: Also high yielding, second to 15 Dias, but not as popular for palatability;
- TIS 2498: Third highest yielding by BLUP estimate, not further noted;
- INIA 18: Lower yields at four months, but relatively high at six months;
- TIS 2534: Noted for relatively high yields and short duration, also a variety which has remained popular for several years;
- Cana Sumana: Not included in trials, initially popular with farmers, but subsequently found to be susceptible to viruses (Henderson et. al. 1997).
Orange-fleshed sweetpotato cultivars, which are very high in beta-carotene used by the body to produce Vitamin A, have become the focus of a nutritional initiative to overcome Vitamin A deficiency, a severe problem to may people of the region. Most studies of varietal acceptance of sweetpotatoes in Africa have held that orange-fleshed varieties were less preferred to white varieties, since they were regarded as too sweet and/or moist, with low dry matter content. However, a study undertaken by the International Center for Research on Women (ICRW) demonstrated that women would accept orange-fleshed varieties if they were sufficiently high in starch, low in fiber, and introduced via an effective health education program. (This study is noted in the Harvest Plus site, Research: Plant Breeding -- Sweet Potato.)
CONSUMPTION, STORAGE, AND MARKETING
Since very little of the sweetpotato crop of Mozambique is either exported or imported -- most is consumed very close to its site of production -- consumption rates can theoretically be well estimated by production data. FAO production estimates for 2003 and 2004, of 66,000 tons, would amount to an average per capita consumption rate for 18,863,000 people of approximately 3.5 kilograms, well below the average for humid areas of central and southern Africa. (Estimated average annual per capita sweetpotato consumption in Uganda is approximately 100 kilograms!) By estimates of the 2004 survey noted in History and Overview, 386,000 tons are produced annually (less average yield but on much more area cultivated). By this estimate, average annual per capita consumption would be roughly 20 kilograms, still probably a very conservative estimate.
In general there is very little processing of sweetpotato for home consumption, storage, or marketing. It is utilized fresh, boiled, or grilled, and sometimes in the form of sweetpotato meal. The extent of marketing is uncertain. SARRNET reported that in 1993/94, nearly thirty percent of sweetpotato was marketed, much higher than most other staple crops and roughly equivalent to legumes. Apart from cash marketing, sweetpotato plays a large role in less formal food exchanges among households (SARRNET 1997).
The primary agricultural research institution in Mozambique is:
Instito Nacional de Investigaçao Agronómica Mozambique (INIA)
[P.O] Box 3658
Mavalane, Maputo
Tel: (258) 1-460190
Fax: (258) 1-460074
Email: uaiene@[iniadta.uem.mz]
Mozambique is a member of the Southern Africa Root Crops Research Network (SARRNET). Summaries of current research, including varietal development and biological controls, are available via SARRNET.
The Famine Early Warning System (FEWS) sponsors FEWSNET, which features reports of food security status in several countries, including Mozambique (in English and Portuguese).
CONTRIBUTORS
Kelly Theisen is the principal contributor to the initial (2006) Mozambique chapter of the Sweetpotato Atlas.
Charles Crissman provided information and advice via personal communication.
REFERENCES
Barreiros, [M.A.L.and] [A.M] Zarias. 1992. Plant Protection for Cassava and Sweetpotato on Mozambique. Root and Tuber Pest Management in East and Southern Africa. International Institute of Biological Control (IIBC). Proceedings of a regional workshop held in Mombasa, Kenya, 10-14 August 1992. IIBC. Nairobi, Kenya.
Columbia Encyclopedia Sixth Edition. 2003. Mozambique. (Accessed 13 June, 2005).
FAOSTAT. (Agriculture/ Agricultural Production/ Crops Primary) and (Population/ Annual Time Series).
Henderson, [S.A]; [L.A] Sitch; P. Macoo; M. Botão; F. Pequenino; J. White. 1997. Multilocation Trials of Sweetpotato Varieties in Northern and Central Mozambique. Roots: Newsletter of the Southern Africa Root Crops Research Network (SARRNET) and the East Africa Root Crops Research Network (EARRNET). Volume 4, No. 1.
Huntington Library Plant Trivia Timeline Accessed 08 June, 2005
ICBL (International Campaign to Ban Landmines) Landmine Monitor, Mozambique. Accessed 06 June, 2005.
IIASA (International Institute for Applied Systems Analysis). Country Briefs: Mozambique (Agriculture). Accessed 04 June, 2005.
IRRI (International Rice Research Institute) and CIAT (Centro Internacional Agricultura Tropical) [RiceWeb] Mozambique. (Accessed 11 June, 2005, apparently not accessible as of 31 August, 2006).
Jimenex, H.; W. Helmskenk; E. Nunes. Recent Research on Sweetpotato in Mozambique. International Potato Center (CIP). Improvement of Sweetpotato (Ipomoea batatas) in East Africa. Workshop on Sweetpotato Improvement in Africa. Nairobi, Kenya. 28 September -2 October, 1987.
Minde, [I.J] and [C.B.L] Jumbe. 1997. Situation Analysis and Outlook of Cassava and Sweetpotato in SADC Countries: Study Report Prepared for SADC/IITA/SARRNET. SARRNET Technical Report 5.
Purseglove, [J.W] 1968. Tropical Crops: Dicotyledons. Longman Group Limited. Essex, England.