INTERNATIONAL POTATO CENTER: WORLD SWEETPOTATO ATLAS
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 notations could be referring to either crop, both of which have become significant to Madagascar.
Agriculture dominates Madagascar's economy, providing the primary livelihood for over three fourths of the population and approximately eighty percent of the country's export earnings (US LOC: Agriculture). Dominant crops include: rice (grown on approximately sixty percent of arable and available agricultural land), cassava (grown on about ten percent of land), and sweetpotato (IFAR, p. 9). Cash crops include coffee, cloves, vanilla, pepper and tropical fruit (New Agriculturalist). Roughly sixteen percent of land under cultivation is irrigated, but in some areas the irrigation system has collapsed as a result of alluvial sand from eroded inland mountainous areas where forests have been cleared (Uppsala). Yields and overall production of food and cash crops have generally been stagnant over the past decade, declining relative to population growth. Roughly half of Madagascar's total landmass supports livestock production (US LOC: Agriculture).
Madagascar's agricultural productivity has been significantly affected by policy fluctuations over the past several decades. Per capita agricultural output suffered a severe decline in the 1970s following the announcement by President Ratsiraka of the redistribution of holdings larger than 500 hectares as an initial step toward the creation of a system based on collective farms supported by an extensive network of parastatal agencies. Area of rice cultivation during this time expanded at the annual rate of approximately three percent, but production increased by less than one percent. As the amount of rice available for marketing declined, Madagascar became a net importer, by an amount of around ten percent of the total domestic crop by the early 1980s. Under the IMF and the World Bank, Madagascar has undergone a phase of structural readjustment which included the disbanding of the state marketing monopoly. Farmers responded with an increase in production, but Madagascar remains dependent on imported rice. On average for the years 1998-2002, Madagascar imported approximately six percent of its total rice consumption, approximately ten percent for 2002, the most recent year reported (FAOSTAT: Food Balance Sheets).
Sweetpotato has become well established in Madagascar due to its high yield relative to both land and labor, its capacity to grow in relatively poor soils in areas where other major crops are less suitable, and its high content of carbohydrates and vitamins, especially vitamin A. Its popularity might also have been enhanced by its relatively independent status, as root and tuber crops are difficult to regulate. By FAO estimates for 2002, sweetpotato was harvested on 94,490 hectares, representing about 3.2 percent of all arable land in Madagascar (FAOSTAT). However, given the very small scale and widespread cultivation of sweetpotato, such estimates are very hard to make. For several other countries in Africa (such as Mozambique), statistics significantly underestimate actual production.
National trends are summarized below.
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 throughout 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. Madagascar, given its current and potential production of sweetpotato, could likewise benefit from this initiative.
For more information, please see:
- Vitamin A for Africa: VITAA
- HarvestPlus: Breeding Crops for Better Nutrition
- HarvestPlus Research: Plant Breeding -- Sweet Potato
GEOGRAPHY AND PRODUCTION ZONES
Physical Geography and Climate
Madagascar can be divided into five geographical regions (US LOC: Geography):
- East Coast;
- Tsaratanana Massif;
- Central Highlands;
- West Coast;
The central highlands, an area of relatively high sweetpotato production, range from 800 to 1,800 meters above seal level (masl). Irrigated rice fields have been constructed out of alluvial plains and marshes (US LOC: Topography). Madagascar was once heavily forested, but clearing over many decades has left only about fifteen percent of the country still under natural forest cover (New Agriculturalist).
Madagascar has been dubbed the "red island', because of the laterite soils that are washed, at an annual rate of 200 tons of topsoil per hectare per year in some areas, down the rivers and into the Indian Ocean, which can be left tinted pink for some distance beyond the coast (New Agriculturalist). The productive capacity of soils in Madagascar can also be limited by aluminum toxicity, low potassium, and phosphorous fixation (IFAR, p. 6).
- 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, Madagascar. Most images are digitized from paper maps, of variable clarity.
The climate is dominated by the southeastern trade winds which form over the Indian Ocean anticyclone, a center of high atmospheric pressure that seasonally changes position. Madagascar has two seasons: a hot, rainy season from November to April; and a cooler, dry season from May to October. Local climate is variable according to altitude and position relative to prevailing winds. The east coast, more directly exposed to the trade winds, receives the heaviest rainfall, averaging as much as 3.5 meters annually, and is subject to destructive cyclones. The central highlands are significantly more arid than the east coast, as rain clouds discharge much of their moisture east of the highest elevations on the island (US LOC: Climate). The areas of highest altitude can be subject to frost during the dry season (Rakotoariosa and Ravoniarimanana 1994). Madagascar is also subject to occasionally severe cyclones.
- Tropical Cyclone Jaya is described in an April 2007 account by Wild Madagascar.
Regional Distribution of Sweetpotato Production
To view this map, click on the thumbnail and expand the image as desired.
For more detailed information about data sources and interpretation, please click here.
Relatively high concentrations of sweetpotato cultivation are found in areas of altitudes of roughly 1,000 to 2,000 meters above sea level in the central region and lower altitudes in the semi-arid southernmost part of the country. Southern Madagascar is generally characterized by some of the poorest soils, driest conditions, and/or highest altitude agriculture in Madagascar, areas which offer few other alternatives of comparable productivity (Rakotoariosa and Ravoniarimanana 1994).
PRODUCTION SYSTEMS AND CONSTRAINTS
Cropping Patterns and Fertility Management
Malagasy agriculture is complex and variable. Traditional methods vary by ethnic group or location, according to population density, climate, water availability, and soil. The most intensive form of cultivation is practiced in the central highlands, where population densities are the highest. At the other extreme are the extensive shifting agricultural systems, such as in the extreme south and southwest, where dry brush or grassland is burned off, and drought-resistant sorghum or corn is sown in the ashes (USLOC: Agriculture). In mid-altitude riverine systems, sweetpotato is sometimes grown in rotation with cassava.
Sweetpotato is generally planted with few, if any, soil amendments, often on marginal land where few other crops can be grown. Yields of 15-20 tons per hectare are possible under higher intensive management with optimal fertilizer application (Rakotoarisoa, 1994 A), but fertilizer use for agriculture in general is very low, averaging about three kilograms per hectare since the mid-1970s. Given that Madagascar produces several high-value crops for export, such as coffee and vanilla, it is very unlikely that fertilizer is regularly applied to sweetpotato (IFAR p. 6).
Planting is from November to May. Harvesting occurs throughout the year, but with some concentration in December, when rice is generally less available.
Occurrence and Control of Sweetpotato Diseases and Pests
(Please note: The brevity of this section should not suggest a lack of disease and pest constraints, but rather an apparent lack of published research on the subject. The topic is covered in somewhat greater depth in the Uganda chapter of the atlas, some points likely relevant to Madagascar.)
Viral Infection has been reported for sweetpotato in other African countries. Sweetpotato virus disease (SPVD), caused by the co-infection of two viruses --Sweetpotato Chlorotic Stunt Virus (SPCSV) and Sweetpotato Feathery Mottle Virus (SPFMV) -- is a serious constraint of sweetpotato in Uganda. Although the effects of the infection on production are not yet reported, the strain of SPCSV found in Madagascar appears to be consistent with the strain found in Uganda, based on relative variation of the HSP70 homologue gene. This strain appears to be distinct from others found in West Africa (Fenby et al. 2002).
Sweetpotato weevils (Cylas formicarius), reported by 1994 (Allard 1994, p. 6), are especially damaging through the dry season, and to stored crops. B.E. Rakotoarisoa (1994 B) has reported that sex pheromones have been used as a tool to trap males and to monitor populations, which generally fluctuate according to rainfall patterns. Although populations are variable by season and locality, the population generally follows a rainfall pattern, decreasing from December to May and disappearing in June, especially in areas subject to frost. Storage root damage is generally greatest from December to May. Early planting, for a harvest in June or July, can help to minimize damage (Rakotoarisoa and Ravoniarimanana 1994, p. 46).
Caterpillars (Acraea acercata) can cause damage at the end of the rainy season, from March to April (Rakotoarisoa and Ravoniarimanana 1994, p. 45).
Locusts. Madagascar has also occasionally suffered extensive crop losses due to locust invasions.
- A report by the UN Food and Agriculture Organization (FAO) and World Food Program (WFP) describes the effects of a locust invasion in 1997.
VARIETIES AND SEED SYSTEMS
A brief outline of research undertaken by the Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA) indicates three varieties being utilized for trials and multiplication:
- Mahafaly (CIP 440 063/ TIS 2544)
- Mahasoa (CIP 440 034)
- Naveto (CIP 440 131).
The variety ClP 440 063/ TIS 2544 was noted by B.E. Rakotoarisoa (1994 A) as performing very well under a wide variety of fertilizer treatments, including manure applied from zero to thirty tons per hectare (T/HA), optimally at twenty T/HA with well prepared, deeply plowed soil. Twenty T/HA manure with one T/HA dolomite fertilizer returned the highest benefit to cost ratio in tests conducted at the Root Crops Research Station, but this is apparently not common practice among farmers.
CONSUMPTION, STORAGE, AND MARKETING
Since sweetpotato is usually consumed close to where it was grown, and there are virtually no imports or exports of the crop, consumption can be well estimated by production. For 2003, Madagascar's 17,404,000 people consumed approximately 509,175 tons of sweetpotato, or about 29 kilograms annually per capita, although this could well be a very conservative estimate of the crop. This is high by world standards, though much less than several other countries of the region, for example Uganda, where annual per capita consumption is over 100 kilograms (FAOSTAT).
Information pertaining to storage and marketing is not readily available.
RESEARCH FACILITIES AND CONTACTS
Sweetpotato research in Madagascar is of fairly recent origin. In 1969, P. Silvestre of the Institut de Recherches Agronomique Tropicales (IRAT) noted that although intensive investigations of cassava in Madagascar had been underway for approximately thirty years, sweetpotato was the subject of only "less important studies" (Silvestre 1969, III-84).
The National Agricultural Research Institute of Madagascar (FOFIFA) is the main research organization of the Ministry of Scientific and Technological Research for Development. By the early 1980s, FOFIFA supported four regional centers and 31 experimental stations and substations (IFAR, p. 9).
Formal research on sweetpotato began in 1988, following a course provided by the International Institute of Tropical Agriculture (IITA) in Nigeria. Research includes clonal evaluations at the station of Fiompiana Fambolena Malagasy Norveziana (FIFAMANOR), as well as on farms. Collections of material maintained in vitro were also initiated at this time (Rakotoarisoa and Ravoniarimanana 1994, p. 46).
Madagascar is a member state of the Regional Potato and Sweetpotato Improvement Network in Eastern and Central Africa (PRAPACE), which developed from PRAPAC, a network established in 1982 by the national research institutions of Burundi, Rwanda and DR Congo to link their potato programs. Currently PRAPACE collaborates with potato and sweetpotato programs of ten member countries of the Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA). Other countries include: Burundi, DR Congo, Eritrea, Ethiopia, Kenya, Rwanda, Sudan, Tanzania and Uganda. CIP provides support in maintaining the availability of sweetpotato germplasm, scientific information, training, and administrative support. The United States Agency for International Development (USAID) funds the network.
The Famine Early Warning System (FEWS), also sponsored by USAID, sometimes carries reports of climate and food security pertaining to Madagascar via FEWSNET.
Kelly Theisen is the principal contributor to the initial (2006)Madagascar chapter of the Sweetpotato Atlas.
Allard, G.B. 1994. Integrated Pest Management of Root and Tuber Crop Pests: The Experience of IIBC in Eastern and Southern Africa, 1988-1992. In: Root and Tuber Management in East and Southern Africa. Proceedings of a Regional Workshop Held in Mombassa, Kenya, 1-14 August, 1992, pp. 3-12. International Institute of Biological Control. Nairobi, Kenya.
ASARECA. 2005. (The report of ongoing research in Madagascar, cited in the "Varieties and Seed Systems" section, is not available via the ASARECA site as of August 2006.)
FAOSTAT (Agriculture, Agricultural Production, Crops Primary, Sweet Potato; Population, Annual Time Series).
FAO. 1997. Special Report: FAO/WFP Mission to Assess the Impact of Crop Damage by Locusts on the Food Supply Situation in Madagascar.
Fenby, N.S.; G.D. Foster; R.W. Gibson; S.E. Seal. 2002. Partial Sequence of HSP70 Homologue Gene Shows Diversity Between West African and East African Isolates of Sweetpotato Chlorotic Stunt Virus. Tropical Agriculture (Trinidad) 79 (1): 26-30.
Huntington Library Plant Trivia Timeline.
IFAR (International Fund for Agricultural Research. 1993. The Role of International Agricultural Research Centers (Madagascar). IFAR. Arlington, Virginia.
New Agriculturalist. Country Profile: Madagascar.
Purseglove, J.W. 1968. Tropical Crops: Dicotyledons. Longman Group Limited. Essex, England.
Rakotoarisoa, B.E. 1994 A . Effect of Soil Amendments on the Yield of Sweet Potato in Madagascar. Tenth Symposium of the International Society for Tropical Root Crops. Salvador, Bahia, Brasil, 13-19 November, 1994, p. 6.
Rakotoarisoa, B.E. 1994 B. Preliminary Results on the Use of Pheromone Traps for Monitoring Cylas Populations in Madagascar. Tenth Symposium of the International Society for Tropical Root Crops. Salvador, Bahia, Brasil, 13-19 November 1994, p. 7.
Rakotoarisoa, B.E. and L. Ravoniarimanana. 1994. Sweetpotato Production, Constraints and Research in Madagascar. In: Root and Tuber Management in East and Southern Africa. Proceedings of a Regional Workshop Held in Mombassa, Kenya, 1-14 August, 1992. pp. 45-47. International Institute of Biological Control. Nairobi, Kenya.
Silvestre, P. 1969. Research on Root Crops by IRAT in Africa and Madagascar. In: Proceedings of the International Symposium on Tropical Root Crops, held at the University of the West Indies, 2-8 April, 1967. Edited by Egbert A. Tai, et. al. Rahaman Printery, Ltd. Trinidad.
Uppsala University: Madagascar Progress Report from the Field Season of 1999: Cropping in Relation to the Land Systems.
US LOC (United States Library of Congress) Country Studies: Madagascar.