INTERNATIONAL POTATO CENTER: WORLD POTATO ATLAS
HISTORY AND OVERVIEW
Potato cultivation in the Andean regions of Peru dates to at least the fifth millennium BC, based on evidence found at sites near Ayacucho, in the south-central Andes, as well as at various Peruvian coastal sites (Cowan and Watson 1992, p. 188). Further evidence that this region is within the potato's center of origin is supported by studies indicating a very high species richness of wild potatoes in northern to central Peru (in the contemporary departments of Ancash, southern Cajamarca, La Libertad and Lima), and an area in the Cusco Department of southern Peru (Hijmans and Spooner 2001). More recent research by David Spooner (2005) provides further evidence for a more specific site of origin in Peru, just north of Lake Titicaca.
Although the potato is Peru's most important food crop and has been essential to the diet of Peruvians for many centuries, production over the past several decades has been greatly affected by forces external to the communities where potatoes are grown. Production and consumption fell sharply from the 1960s to the mid-1980s, due largely to economic policies which made potatoes more expensive than imported and locally produced cereals. The Sendero Luminoso insurgency, beginning in 1980, caused tremendous disruption throughout Peru, especially in the Andean regions where most potato production occurs. With a more market-liberal economic policy and the termination of the insurgency in the mid-1990s, potato production and consumption have rebounded. Overall, Peru's potato production trend since the 1960s is of higher average yields on less area.
- For a chart of Peru's estimated potato production over the past several decades, please see Production Charts.
- An update (April 2007) indicates that potato production in Peru for the month of January 2007 is nearly 25 percent higher than January 2006. Please see the Global Potato News entry for April 17 (requires free registration with Syngenta).
The potato in Peru is primarily a crop of independent farmers with small landholdings. As of 1984, approximately 75 percent of all production occurred on holdings of less than three hectares devoted to potatoes, and only five percent of production was on large holdings, greater than twenty hectares (CIP/ PRACIPA 1984, cited in the United Nations Food and Agriculture Organization (FAO)). That trend seems persistent; as of 1990, more than eighty percent of the potato crop (by area) was being produced by small-scale farmers cultivating less than one hectare of potato (Vilca 1990, cited in Brown and Scheidegger 1995).
Peru is considerably more urbanized than its Andean neighbors Bolivia and Ecuador. From 1975 to 2002, the urban population grew from approximately 61 to almost 74 percent of the national total, with roughly one third of Peru's total population living in Lima (UNDP). Urban markets are therefore extremely important to commercial potato production, including specialized commercial production in coastal valleys.
GEOGRAPHY AND PRODUCTION ZONES
The opportunities and risks facing potato farmers in the Andes vary greatly with geographic factors. Most generally, the Andean region can be classified into three agroecological zones (Tapia 1993, cited in Hellin and Higman 2002, p. 3):
- Green Andes (northern Peru and Ecuador) with generally adequate rainfall and minimal climatic variability;
- Yellow Andes (central Peru and eastern Bolivia) with more variable rainfall;
- High Climatic Risk Andes (southern Peru and the Bolivian Altiplano).
These distinctions should, however, be treated as very broad categories of limited use in understanding particular places, since the Andean Region is very complex and locally variable. Across even short horizontal distances, differences in altitude, slope and aspect can result in a tremendous diversity of soils, drainage, solar exposure, diurnal temperature regimes, and evapotranspiration conditions. Zones where agriculture is feasible within a valley are often isolated from other agricultural zones of adjacent valleys by extensive areas of very high altitude (Brush et. al. 1994).
- Many 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, Peru. Most images are digitized from paper maps, of variable clarity.
Potato cultivation is an important element of a larger system of vertical control, by which a community simultaneously exploits ecological zones within this complex Andean environment. The cultivation of potatoes and other tuber crops generally occurs in the puna or jalka, below areas subject to frost which are used primarily for pasture, but at higher altitudes than the kichwa zone, where grain crops are usually grown. The lowest major crop zone, called the montaña, yunga, or temple, is utilized for tropical crops such as sweetpotato, coca, sugar cane, manioc, plantain, and other fruit. It is common for Andean communities to be located near the boundary separating the kichwa and jalka zones, in close proximity to land suitable for potatoes, but also accessible to grain crops below and pasture above (Brush 1977, pp. 8-13). Vertical control is a strategy pursued by individual farming households at a local scale, as well as by communities. Potato farmers in the Andes typically work several non-adjacent plots, sometimes scattered widely over land held by the community, in order to take advantage of a variety of environmental niches (Brush 1977, p. 6; Paige 1975, p. 192).
Regional Distribution of Potato Production
More than ninety percent of Peru's potato crop is produced at altitudes above 2,500 meters above sea level (masl) to a limit of just over 4,000 masl (for bitter potatoes), in the central Andes. A smaller area (estimated 5,000 to 10,000 hectares) in the coastal valleys west of the Sierra is devoted to commercial production under irrigation to meet the demand for potatoes in urban markets, primarily Lima, when potatoes from the Andes are less available (Brown and Scheidegger 1995, p. 65). Although this area is at a much lower altitude than the Andean potato crops, the Pacific Humboldt current keeps night temperatures sufficiently cool to allow for potato tuber formation.
- A map of potato distribution in Peru can be found on the Country Maps page.
PRODUCTION SYSTEMS AND CONSTRAINTS
The Agricultural Calendar
An important management strategy of vertical control is the opportunity it provides farm communities to maintain relatively consistent labor demand and food supply across the calendar year. The potato cropping calendar must therefore be seen within the context of a wider agricultural calendar that is both complex and full. For example, in Uchucmarca, a village near Cajamarca in the "Green Andes," potato harvests generally occur from December through March, maize in March and April, and wheat, barley, beans and lentils in July and August (Brush 1977, p.100). Since local environmental variations can determine cropping cycles (e.g. the duration of a crop to maturity, generally longer at higher altitudes), there can be considerable variations of the cropping calendar locally across environmental niches as well as temporally over the years.
Generally for the Peruvian Andes, potato production is divided into two cycles, "early planting" (maway tarpuy, also known in Quechua as misqa) and "big planting" (hatun tarpay), although the cycles can generally be considered synonymous with physical zones.
Early Planting (Maway Tarpay). Cultivation for the maway cycle, typically at altitudes between 3,000 and 3,800 masl, begins from June through September, for a harvest from September through February, depending on the variety and local conditions. In the higher altitude central and western Andes, the maway is generally small, and the hatun tarpay is more important (S. de Haan, personal communication). However, on the eastern Andean slopes, facing the Amazon, the maway is the main crop because the season coinciding with a hatun crop is very wet, increasing the risk of late blight.
Big Planting (Hatun Tarpay). Cultivation begins from October through December, with harvest from March through June, typically at altitudes from 3,800 to 4,100 masl, depending, as usual, on the variety and local conditions. Species of bitter potatoes (more on this topic under "Varieties and Seed Systems") are usually planted earlier and harvested later than other species because of their longer vegetative period.
An exception to the more clearly defined maway and hatun tarpay seasonal patterns is the cultivation cycle of Solanum phureja, an early maturing and non-dormant species which is cultivated up to three times annually at altitudes up to 3,000 masl, but seems especially prone to genetic erosion and subsequent cultivar loss (S. de Haan, personal communication).
Coastal Valley Operations. Where irrigation is available, coastal valleys have become centers of commercial potato production. In this system, the agricultural calendar complements the Andean crop, as potatoes are planted between May and July and harvested and marketed from August to December, when Andean potatoes are not sufficiently available to meet urban demand (Brown and Scheidegger 1995, p. 65). Fallow is not common, as land is usually being cultivated by a commercial crop, sometimes potato in rotation with cotton, maize, or vegetables for urban markets.
Other Timing Factors. Within these seasonal constraints, in many Andean communities agricultural operations are also partly determined by phases of the moon. Agricultural activity is generally considered hazardous on the day of a new moon or full moon. A waxing moon following the new moon (the luna verde, or green moon) is considered a positive force for crop growth, while the waning moon indicates negative force. However, the relative strength of the lunar phase is balanced against the perceived level of soil fertility. The overriding principal is that the two forces, lunar phase and soil fertility, should not be in harmony, but rather in opposition to each other. Two positive forces (a plot of high soil fertility combined with a waxing moon) might provide excessive energy to plants, so that they expend too much energy on vegetative growth at the expense of crop development, while labor applied during a waning moon on a plot of low fertility will result in low plant growth and crop failure. Harvesting is best done during a waning moon of negative force, since positive force at this time would only contribute to pests. Since most farmers are cultivating a mix of more and less fertile plots, their allocation of labor across each is partly guided by lunar phase (Brush 1977, pp. 102-103).
In southern Peru and Bolivia, an area more prone to drought and climatic risk, farmers have been guided in the timing of their potato cultivation by other celestial observations. Every year during the festival of San Juan in late June, coinciding with the southern winter solstice, farmers observe the visibility of the Pleiades, a cluster of stars within the Taurus constellation. If the Pleiades appear especially radiant with all stars easily counted, farmers can expect plentiful rainfall four months later and a good harvest of potatoes planted later in the season. If the Pleiades appear faint, little rain can be expected later in the season and early planting is essential. What might seem to be an anthropological curiosity has been supported by further scientific investigation. Poor visibility of the Pleiades in June, caused by cirrus clouds at high altitudes which are not readily seen but can affect starlight perception, is an indicator of an El Niño year, which in this region is usually linked to reduced rainfall several months later (Orlove et. al. 2001).
Land Tenure and Distribution
Following the agrarian reforms of the 1960s and 1970s, Peruvian landholding, once dominated by large haciendas, has become more egalitarian. Much of the newly distributed land was maintained as collective holdings, Cooperativas Agrarias de Produccion, or CAPs (Atle et. al. 2003). As described by Stephen Brush (1977) for Uchucmarca, near Cajamarca in the north central Andes, usufructory rights, i.e. right to use a plot of land, were typically granted in such a way that plots are regarded as private property within the community. Land could be inherited or exchanged with other members of the community, but could not be alienated from the community by sale or exchange to outside individuals or interests. Land which is less productive to agriculture, such as grazing areas of the jalka fuerte, was often held in common.
Even with the demise of a tenure system dominated by large haciendas, land holdings within peasant communities are not perfectly egalitarian. In the Andean community described above, a concentration of landholdings, either by purchase or inheritance, was more typical of land in the kichwa and templado, the primary cereal-producing zones at altitudes below the jalka where potato cultivation is concentrated. Land in the jalka was available, by petition to the community, to bona fide community residents and, to a lesser extent to recently arrived immigrants or families headed by men who had married into the community (ibid.).
There has been a move in recent years to promote more individualized titling of land. In the 1980s, most CAPs informally divided lands among members, although capital assets and some land has remained under collective ownership (Atle et. al. 2003). During the term of President Fujimori, beginning in 1990, the government promoted further individual land titling via legal reforms intended to encourage the options of farmers to sell, rent or mortgage land. By 1994, 41 percent of agricultural land was under some form of title, but little of it (17 percent) was registered with the government, in large part due to the legal and bureaucratic difficulties in doing so (del Castillo, cited in Atle et. al. 2003). Most agricultural land in the Andes, especially where potatoes are grown, remains essentially a community asset available to individual members.
Cropping Patterns and Fertility Management
Fallows and Crop Rotations. In the higher altitude Andes (3,500 to 4,300 masl), rotations and fallow systems are commonly based on communal land tenure systems, under local names such as laymes, suretes, anyokas, or aisha. The rotation typically begins with native potatoes, followed the second year by mixtures of other Andean tubers oca, mashua, and/or olluco, and the third year by quinoa or barley. Depending on local population pressure, a subsequent fallow period might last from two to seven years. Another common practice is known as majadeo, where native potato cultivation is mixed with pasture rotation. Potatoes are generally planted in areas where cattle have been more concentrated to take advantage of residual manure. Fallow can range from three to ten years, depending on the location and availability of land to the local community (S. de Haan, personal communication).
At lower altitudes, rotation designs are extremely variable. Potatoes are more likely to be "improved," as opposed to native varieties, and are grown with a wide variation of rotation systems, often including faba beans, alfalfa, and/or maize. Fallows are usually shorter, perhaps two years long, and potatoes might be cultivated on a given plot after an interval of three to five years (ibid.).
Erosion and Terracing. Potato cultivation on the sloping land of the Andes can cause serious soil erosion, a challenge which farmers have managed for centuries with agricultural terracing. A tradition of extensive terracing is generally limited to southern Peru, although elsewhere, for example near Cajamarca, farmers typically construct contour parallel retention walls which impede soil runoff and slowly form slightly inclined terraces (Becker 2001, p. 11). Very extensive terracing dating back at least 500 years (often much longer) can be seen in several areas of southern Peru, such as the Colca Valley near Arequipa. Although a precise inventory of terraced land area in Peru has never been undertaken, CEPAL (Comision Economico para America Latina y el Caribe) estimated the area of terraced fields at two million hectares in 1989 (cited in Inbar and Llerena 2000, p. 72), most of which had been abandoned. A 1986 study of the Colca Valley estimated that 62 percent of terraces were abandoned, over 90 percent at higher altitudes (Denevan 1886, cited in Inbar and Llerena 2000, p. 72). Abandonment is almost total on non-irrigated terraces in areas where irregular rainfall makes the investment of seed and labor doubtful, especially when crop prices are low (Inbar and Llerena 2000, p. 78).
Erosion rates are strongly affected by degree and type of vegetation cover, but are indirectly a function of labor shortage, hence reduced maintenance of protective structures, resulting from out-migration of people from Andean communities to cities. For example, in the Eulalia River Basin, approximately eighty kilometers east of Lima, population growth remains static in spite of a high birth rate as young people migrate to the Lima area. Sediment yield values, measured via simulated rain studies, were generally very low on terraces still in cultivation, but could be very high in years of intensive rains, as can occur in El Ninoyears. High magnitude rain storms can be extremely erosive on uncultivated and poorly maintained terraces. Ironically, the erosion of soils in many Andean communities might be caused by a reduced human presence, as soil follows the migration of people to cities, mostly to the coast (Inbar and Llerena 2000, p. 78).
Commercial Fertilizers. The use of commercial fertilizer for potato cultivation in Peru follows a very general pattern distinguishing smallholder and commercial production. Most of the country's potato crop is grown by independent farmers, usually for some mix of subsistence and commercial sale, with very low levels of commercial fertilizer and other purchased inputs. However, such inputs are heavily used by larger scale commercial potato producers, typically in coastal valleys west of the Andes. A recent survey of La Encañada, an area also near Cajamarca, indicated that only thirty percent of potato farmers in the area applied fertilizer, though some applied chicken manure when it was available. For those using fertilizer, the average application rate was approximately thirty kilograms (kg) nitrogen per hectare. By comparison, in the Carchi area of Ecuador, where more intensively commercial production has been underway for several years, farmers typically apply 140 kg nitrogen (and other nutrient elements) per hectare (Bowen 2003).
Occurrence and Control of Potato Diseases and Pests
This list is not complete, but includes several diseases and pests known to be serious constraints to potato cultivation in Peru. For more technically specific information (though not usually specific to Peru), please refer to the relevant sites included in:
Late Blight (LB). This disease, known in some areas of Peru as rancha, is caused by the oomycete pathogen Phytophthora infestans. LB is the most serious biological constraint to potato production in Peru, and worldwide. It is particularly severe in areas of cool moist climate, especially under conditions of nearly continuous cultivation where spores of P. infestans are always present as inoculum. An estimated fifteen percent of the Peruvian potato crop is lost to LB, in spite of very heavy applications of fungicide sprays (T. Walker, personal communication cited in Nelson et. al. 2001). Farmers' perceptions seem to be consistent with these estimates; in a survey undertaken in 1997 and 1998, LB was identified by Peruvian farmers as their most serious biological constraint (Ortiz et. al. 1998, p. 102).
Many farmers use fungicide sprays as their primary means to control LB, although at least one fungicide, metalaxyl, was reportedly losing its effectiveness. Formulas in use include dithiocarbamate fungicides, which have been classified by the US Environmental Protection Agency as probable human carcinogens (Nelson et. al. 2001, p. 688). The monetary cost of fungicides to farmers varies widely, but averages approximately US$150 per hectare, equivalent to 10-15 percent of total production costs (Ortiz et. al. 1998, p. 106). Although the diffusion of LB resistant varieties can potentially address this problem, farmers often maintain fungicide applications even with resistant varieties, perhaps because they plant resistant and susceptible varieties together in the same plots, and spray all in common (ibid., p. 105).
Beginning in 1994, the International Potato Center (CIP) has worked with the non-governmental organization (NGO) CARE to better understand, via Farmer Participatory Research, the perceptions and practices of Peruvian potato farmers regarding their management of potato pests and diseases. This effort has included a major focus on LB since 1997 with the general goal of providing farmers opportunities to learn more about LB; to be involved in the testing and selection of varieties resistant to LB; and to develop additional methods to control diseases and pests; and to improve overall crop management (Nelson et. al. 2001). The program has included Integrated Pest Management (IPM) techniques to explore alternatives to exclusive use of fungicide sprays. The participation of farmers in this work has been successful in identifying varieties that are not only LB resistant, but also meet other needs.
For more information, please see:
Black Scurf (Rhizoctonia solani). This is a fungal infection that attacks tubers, underground stems, and stolons of potato plants, especially in cool, damp soils. Although black scurf generally does not damage the tuber, the cosmetic effect can seriously diminish the value of potatoes produced for specialized markets requiring washed and healthy looking produce (G. Forbes, personal communication).
Viral Diseases. Considering that the potato's area of origin lies within contemporary Peru, it is not surprising that many viruses which affect potatoes have been identified here. Viral infection of potatoes can be transmitted via seed tubers, causing a gradual deterioration and loss of yield. However, the process occurs more slowly at higher altitudes. One recent survey has indicated that viruses are not a leading cause of tuber-seed degeneration at the higher altitudes (above 2,800 masl) where most potato cultivation in Peru takes place (Fankhauser 1999), but the issue remains under investigation. Viruses considered most potentially responsible for tuber degeneration include PVX (Potato Virus X), PVY, and PLRV (Potato Leafroll Virus) (Khurana and Garg, 2003, p. 168).
Bacterial Wilt. A soil-borne disease which can lead to complete loss of a potato crop, bacterial wilt is not reported in the Andes at higher altitudes (again, above approximately 2,800 masl), but could pose a threat to more commercial production at lower altitude coastal sites.
Andean Weevil. This insect pest (Premnotrypesspp.) can be a serious constraint to potato production, especially at higher altitudes (above approximately 2,800 masl) in Peru and elsewhere in the Andes.
Adult weevils, flightless and inconspicuous, enter potato parcels from adjacent fields and lay their eggs at the base of potato plants. At this point they are most susceptible to insecticides. However, if farmers do not fully understand the life cycle of the weevil, they are likely to wait until the white larva are visible in the dark soil before taking action. Weevil populations are likely to increase under continuous potato cultivation, as they remain in tubers not removed from harvests. Crop rotation, including pasture, therefore remains an important control measure (Crissman, Espinosa et. al. 1998, pp. 104-105).
The Andean weevil has few natural enemies present in potato plots, which challenges the potential for IPM strategies. However, some IPM methods have been attempted, for example in Ecuador where farmers are using traps in which potato foliage treated with an insecticide of reduced toxicity is used as a bait for the adult weevils (G. Thiele, personal communication).
Potato Moth. Larvae of this moth can mine their way into tubers, causing damage by way of stand reduction or stunted plants. CIP has worked toward the development of the granulosis virus as an IPM technique.
Leafminer Fly. This fly, Liriomyza huidobrensis, can become a constraint to potato production as newly hatched larvae feed on leaves, resulting in characteristic brownish "mines" which progress to necrotic brown leaf tissue and a reduction in photosynthetic capacity. The fly can become a serious pest in areas where insecticides have been used intensively (reducing the populations of insects which control the leafminer) and where particularly susceptible cultivars are planted, in Peru most characteristic of coastal production. The fly is a native to South America, but has become a pest of potato crops across several continents.
Management strategy is based on the use of resistant or tolerant potato cultivars and habitat management to favor the increase of natural enemies. Traps to capture adult flies and selective insect growth regulators have been used when the fly becomes a serious pest.
- For more information about Integrted Pest Management (IPM) strategies developed by CIP in the Cañete Valley of Peru, please see IPM of Leafminer.
VARIETIES AND SEED SYSTEMS
As a result of the physical isolation of Andean valleys, wild potato populations can persist locally with little exchange across nearby sites. Much the same is apparently true of cultivated potatoes, as crop populations likewise can remain localized. Over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household (Brush 1992, p. 151). By necessity, the strategy pursued by most Andean potato farmers has been to remain essentially self-sufficient, although exchange has increased with greater commercialization (Brush et. al. 1994, p. 1191).
The close attention paid by Andean farmers to their wealth of potato varieties is apparent from the nomenclature they have developed as a necessary tool to distinguish, and therefore maintain, such a wide range of varieties. A survey undertaken in the late 1980s with farmers whose fields range from 3,600 to 3,850 meters above sea level (masl) in the Province of Paucartambo, Department of Cusco in the south-central Peruvian Andes, asked them to provide the local names used for recognized potato varieties, which were compared with the genetic variability of each as indicated by electrophoretic phenotypes. Correspondence between farmer identification and electrophoretic phenotypes was high at a small spatial scale (especially an individual farm), but this correspondence eroded between farms and especially across larger regions. The most common error was to apply the same local name to different types, thereby underestimating the degree of genetic diversity in their collections. To the extent that this is true in general, it suggests that there may remain a substantial amount of unexplored variation in populations of cultivated Andean potatoes (Quiros et. al.), and could likewise be a cause for error on the side of underestimating genetic variety present within in vitro collections.
Seven species of potato are currently grown in the Andes, including Solanum tuberosum and six other cultivated species exclusive to the region. Four ploidy levels have been identified, from 2n = 24 to 2n = 60. The tetraploid S. tuberosum ssp. andigena is by far the most common, accounting for more than two thirds of cultivated potatoes (ibid). Natural hybridization between cultivated and wild species has rarely been reported, in part because of the common practice of abandoning fields after one year of cultivation (Brush et. al. 1994, p. 1190). Wild Andean species have, however, been utilized for artificial crosses (Hawkes and Hjerting 1989).
Hundreds of different varieties of potatoes currently cultivated can very generally be distinguished as:
- "Improved varieties," produced and distributed by breeding programs, usually incorporating specific traits (such as resistance to particular disease(s));
- Commercial native varieties, not obtained via the formal system, but intended for markets;
- Non-commercial native varieties, grown for local consumption (Thiele 1998 p. 87).
An additional species, the bitter potato (Solanum x juzepczukii, Solanum x curtilobum) is cultivated at altitudes between 3,000 and 4,300 masl, typically on land also used for pasture, often under rotation with fodder crops such as barley or oats and with fallow periods of several years. The bitter potato tolerates frost far better than other potatoes due to a high concentration of glycoalkaloids, sufficient to make it toxic to humans in its natural state. Bitter potato genes have been used more for the improvement of other potato varieties than for programs directed toward the bitter potato itself (Arbizu and Tapia 1994).
To process the bitter potato into an edible product, Andeans have for many centuries prepared chuño. The potatoes are spread on the ground and allowed to freeze overnight, then stomped underfoot while still frozen the following morning. The resulting pulp is dried in the intense mid-day sun under a layer of straw. This process is repeated daily for approximately two weeks, and the product is further dehydrated, resulting in black chuño. Additional washing, and some additional days processing, can result in white chuño. It is used in stews or eaten like bread and can be stored for up to ten years (ibid.).
Since chuño cannot be made without an extreme diurnal temperature range, the northern limit of chuño production is roughly the "Green Andes" of the Cajamarca area (Encyclopedia Britannica). As such, chuño represents a climatic challenge which people have not only endured but transformed into a creative force. This process of preservation via freeze-drying has been used for many other substances, including meat; the English term "jerky" is derived from the Quechua ch'arki (ibid.). Freeze-dried foods such as chuño provided the means for the Inca empire to maintain extensive stores of food for long periods of time as insurance against famine and to sustain armies in the field.
- For a description of bitter potato and several other Andean tubers -- oca, mashwa, and ulluca (also known as papalisa) -- please see Andean Tubers, by C. Arbizu and M. Tapia of CIP.
- The INCOPA Newsletter article, Rescuing an Ancestral Flavor, contains more information about the preparation of white chuño.
Modernization and Diversity
The enormous genetic diversity of potatoes found in the Peruvian Andes is under threat of "genetic erosion," i.e. the loss of genetic variation and the subsequent reduction of the genetic base of cultivated potatoes, due in large part to commercial pressures and the introduction of new varieties (often grown to meet commercial market preferences) which could displace local landraces. However, the extent and the rate of genetic erosion remains uncertain.
A complete assessment of the effects of modern potatoes and commercial markets on the population structure of native potato varieties could only be made in reference to a thorough baseline survey of landraces in a given area prior to the introduction of improved varieties. However, in the absence of such data, an estimate of these effects was made via a comparison, in 1990, of two areas apparently similar in their initial richness of native varieties, but varying by the degree and length of time of their adoption of modern varieties. The two areas are Tulumayo Valley, fifty kilometers east of Huancayo in central Peru, and Paucartambo Valley, fifty kilometers east of Cusco, farther south. Both are well known as centers of potato diversity, from which seed tubers of native varieties have been exported to other regions. Improved varieties were first introduced to Tulamayo in 1950, and to Paucartambo in 1960. The other outstanding difference between them is that Tulamayo is in many respects the more "modern" community, much more integrated into the larger regional economy via off-farm employment and migration, and more Spanish speaking. Paucartambo, in contrast, is predominately Quechua speaking and otherwise maintains a more Indian ethnic identity. In both communities, land distribution is fairly egalitarian, reflecting recent agrarian reform and redistribution of abandoned land (Brush et. al. 1991, pp. 374-375).
In most respects, the comparison between the two communities was consistent with expectations, e.g. that farmers in the more "modern" Tulamayo grew a much higher proportion of improved varieties (as measured by land area), invested more in their potato crops, achieved higher yields, and sold a higher proportion of both landraces and modern varieties. Yet, perhaps paradoxically, farmers in Tulamayo grew on average a higher number of native varieties, though on less land (Brush 1992). One possible pattern over time, though difficult to verify absent a much wider and more extensive study, is that a period of rapid genetic erosion occurs shortly after the introduction of new varieties, but that the system subsequently reestablishes a balance in which native cultivars are retained.
Vertical control (please refer to the "Geography and Production Zones" section), an essential feature of Andean agricultural management, seems to be relevant to the retention of potato landraces. In both communities, improved varieties were concentrated in the intermediate altitudinal zone (between 3,000 and 3,800 masl), while landraces were concentrated in the higher zone, from 3,800 to 4,100 masl.
Since landraces are generally cultivated together in common lots, without a spatially distinct plot for each variety, it might be expected that less area devoted to landraces would result in varietal loss via random elimination, though perhaps some compensation would occur via inter-household exchange. Although a comparison of two sites provides insufficient data on which to base any conclusion, exchange of native seed appears to be much more common in the more "modern" Tulumayo Valley, although sale of native seed was indicated by the survey as slightly more common in the more "traditional" Paucartambo Valley (Brush et. al. 1992).
The individual farm household seems to be the relevant unit of management, and there are many reasons why Andean farmers might choose to retain some landraces in spite of their adoption of modern varieties, such as:
- Inherent qualities: Landraces often demonstrate inherently superior qualities, such as culinary appeal or improved storage capacity due to higher content of dry matter (Brush 1995, p. 348);
- Socio-economic factors: Adoption of modern varieties in Paucartambo seems to be sensitive to socio-economic status. Other factors being equal, both rich and poor farm households were relatively low adopters of modern varieties. Absent access to insurance and credit markets, and perhaps information about new technological options, poor farmers seem to be discouraged from taking the risk of planting a large portion of their farms to modern varieties. Rich farmers, on the other hand, may be "low adopters" of modern varieties because they can afford the luxury of growing traditional varieties which are generally considered superior potatoes (Brush et. al. 1991, p. 379);
- Cultural reasons: For example, landraces are prized as gifts and are expected as payment for exchange labor in many Andean communities (op. cit.);
- Marketing: Commercial native production accounts for an estimated fifteen to forty percent of agricultural plantings in central and southern Andean highland regions of Peru (Zimmerer 2003, p. 108). Although larger markets generally favor a small range of familiar varieties, there are "niche markets" for traditional varieties, including tuber seed. Occasionally a new variety gains some market popularity, for example "commercial native" varieties of the papa amarilla ("yellow potato") widely marketed in Peru, even in Lima supermarkets;
- Longer-term subsistence strategy: The maintenance of local varieties does not necessarily reflect a resistance to change on the part of Andean farmers, but perhaps a means to keep many options open for using a heterogeneous environment and for meeting different goals and needs.
These factors might be most pertinent to the "core area" of potato diversity, the Andean region from central Peru to northern Bolivia. Outside this area, the potential for genetic erosion might be greater (Ochoa 1975). Carlos Ochoa has provided an example of Solanum hygrothermicum, a potato once cultivated across a wide area from southeast to northern Peru, in forested areas of considerable altitudinal range, but well adapted to survival in the warm humid regions of Peru. However, as of 2000, living collections of this species could not found, largely due to the social disruption of Peru and subsequent breakdown of long-established agricultural traditions (Ochoa 2000).
The "Informal" Seed System
A "seed system" is broadly defined as "an interrelated set of components including breeding, management, replacement and distribution of seed." (Thiele 1998, p. 84). Most tuber seed used in Peru, as elsewhere in the Andes, has been produced and distributed by farmers themselves (the informal system).
Farmers generally do not maintain a specialized plot for the production of seed, but instead they separate part of the main harvest for this purpose. Classifying tubers at harvest is often a responsibility of women, who play a central role in the management of seed tubers (Brush 1992, p. 167; Zimmerer 2003, p. 116). Varieties are kept separate, except for non-commercial native varieties which are more likely to be sown mixed (Thiele 1998, p. 86). Seed tubers are generally stored in houses, not in special stores (Horton 1987, p. 136, cited in Thiele 1998, p. 86).
Size preference for seed tubers is determined within the context of other essential needs, subsistence and (for most households) commercial sale. The resulting preference is often for seed tubers of medium to small-medium size, but this does not necessarily mean that in an ideal world, bigger seed tubers would always be better. Where farmers plant part of their potato crop in areas prone to regular moisture stress at the beginning of the growing season (the "big planting" or hatun tarpay) in October or November, the preference is usually for larger seed, while areas of moderate risk are better suited to smaller tuber seed. The selection of tuber seed size appropriate for particular niches thus provides an example of intra-varietal adaptation which the "informal system" (i.e. farmers themselves) carefully manage, but which might not be fully considered by the formal system (Zimmerer 2003).
Local seed flows making up the informal system are often complex and operate over considerable distances. Areas which specialize in tuber seed production are generally at higher altitudes, where seed degeneration due to viral infection occurs much more slowly. Farmers at intermediate altitudes acquire seed, use it to produce ware potatoes (for consumption), and often multiply it for their own use. Farmers at lower altitudes, such as on the Peruvian coast, only produce ware potatoes for commercial sale, and are more likely to buy seed from the highlands every year (Brown and Scheidegger 1995, p. 66). As noted above in the description of the Paucartambo and Tulamayo Valleys, areas can become well known for the high quality of their seed, both modern varieties and landraces. The quality factor would thus seem to be the area and its farmers, not just the available varieties, which in any case are always changing.
The system requires a coordination over time as well as space, since seed tubers must be available from one area when new production is getting underway in another (Thiele 1998, p. 88). This does not always occur smoothly. Zimmerer (2003, p. 115) reported that in spite of the high cost of seed in Paucartambo (east of Cusco), estimated at ten to thirty percent of total production, supplies of tuber seed in local markets (either in Paucartambo or Cusco) were not always reliable.
The "Formal" Seed System
The formal system refers to seed tubers produced and distributed by state-sponsored institutions (possibly with some involvement of the private sector and/or non-government organizations). Seed from the formal sector has generally been subject to an inspection process intended to assure that the seed is of the variety claimed, with low incidence of disease or pest infestation, and otherwise viable. Such seed is often referred to as "certified seed," although the precise definition of this term is locally variable. Only a small proportion of all tuber seed used by farmers in Peru is provided by the formal system, estimated at less than five percent of total demand for Andean countries in general (Fankhauser 1999).
The formal system in Peru has been important primarily as a means to introduce new varieties, including many selected for resistance to specific hazards, in particular late blight. Farmers have been actively involved in the process of selecting new varieties, increasing the likelihood of their wide adoption (Thiele 1998, p. 90). The use of tuber seed obtained via the formal system is most likely to be profitable for farmers if they obtain small quantities which they subsequently multiply, depending on such factors as the price of seed, the potential difference in yields, and the importance of disease resistance. The SEINPA project, for example, has distributed small packets of tuber seed of varieties developed by CIP, both as a direct injection with little further attempt at modifying the informal system, and by establishing entrepreneurial groups that grow and distribute seed (Thiele 1998, p. 95).
CONSUMPTION, STORAGE, AND MARKETING
Potato consumption in the 1960s stood at approximately 100 kg per capita, but had fallen to approximately 45 kg per capita by the mid-1980s. Potatoes had become expensive relative to cereals due to several policy factors, including an overvalued exchange rate, subsidies of domestic cereal crops, price controls, and other market restrictions (Scott et. al. 2000, p. 12). The Sendero Luminoso insurgency, lasting from 1980 until the early 1990s, caused serious disruption throughout much of Peru, and drove thousands of rural Peruvians as refugees into urban enclaves. By the late 1980s, the price of potatoes relative to rice had reached an historic high in Lima, by then accounting for roughly half of the nation's demand for purchased food. With the end of the insurgency and more market-liberalizing policies in the 1990s, the relative price of potato had declined with increasing production. By 1995, consumption had rebounded to 65 kg per capita (ibid.).
The long-term and often very large-scale storage of potatoes was an essential element of the food security system of the Inca empire. Areas of high altitudes and colder, drier climates were often utilized for the network of state-organized storage facilities, such as found in the Mantaro Valley between Ayacucho and Huancayo in the south-central Andes, where archeologists have estimated the capacity of storehouses at about one and a half million bushels of grain, tubers, or other food. (D'Altroy and Harstorf 1984). Some Andean farmers continue traditional practices such as storing potatoes with leaves of local plants such as muña (Mintostachus mellis), an aromatic plant with insect repellent qualities.
The commercial availability of potatoes in Peru is fairly consistent across the calendar year, through the Andean "early planting" and "big planting," and the more commercially specialized crop grown in coastal valleys. Large facilities for longer term storage are therefore no longer common (Wustman, et. al. 1985). Most farm households maintain potatoes (both ware and seed) for several months at home, though usually not in specialized storage structures.
Most Peruvian potato farmers participate in markets, but are not commercial specialists. Rather, it is more common for farmers to rely on partial commercial production of a diverse range of varieties. As of 1990, the Peruvian potato crop destined for commercial sale was estimated at 40 percent, with 35 percent locally consumed, 16 percent retained for seed, and 9 percent used for exchange and other purposes (IICA - PROCIADINO, cited in FAO). Commercial specialization is hampered by declining potato prices, which in real terms have fallen by more than 200 percent since the late 1980s, due largely, as noted above, to the resumption of higher potato supplies and restored market access following the termination of the Sendero Luminoso conflict (Zimmerer 2003, p. 107).
A farmer's access to commercial markets is obviously variable, one significant factor being infrastructure, especially roads and the availability of transportation (Escobal). However, access to market information is also a significant factor, perhaps independent of infrastructure. A survey undertaken in 2001 from the Tayacaja Province, southeast of Huancayo in the south-central Peruvian Andes, described what is a typical range of options for Peruvian potato farmers: they can sell potatoes to buyers who travel the area offering to buy directly at the farmgate; they can sell at local markets (in this case either of two); they can sell at larger, more distant markets (in this case either Huancayo or the more distant but much larger capital city, Lima) (Vakis et. al. 2002).
This survey indicated that, as expected, greater access to markets (largely determined by the proximity and conditions of roads) favors commercial activity, for example as correlated with larger average transactions. However, there is some evidence that farmers with poor access to markets are those most likely to rely on local markets; improved market access increases both the likelihood of farmgate sales and sales to more distant markets (ibid.).
The survey also revealed the importance of less tangible factors:
- Information: Farmers were more likely to sell in markets where they knew the current potato prices with a high degree of confidence, as revealed by the accuracy of their current price estimates and their experience of obtaining the prices they expected;
- Relationships with potential buyers: Farmers' bargaining skills seemed most important in determining price variation at farmgate and distant market sales, where they were least likely to know the buyers;
- Personal attributes of the farmers themselves: Farmers who sell in more distant markets are usually wealthier, better educated and more likely to speak Spanish, have more marketing experience, and grow a higher proportion of "improved cultivars" demanded by markets (ibid.).
Although physical infrastructural development is undoubtedly a very important factor in reducing market transactions costs, other steps aimed at increasing the availability of information and the bargaining position of farmers could also be significant. Possibilities include local committees responsible for the collection and dissemination of market information, and cooperative schemes which would allow farmers to participate in higher volume transactions, especially if many do not speak Spanish (ibid.).
At the national level, Peru is essentially self-sufficient in potatoes, with neither a significant import nor export volume. One exception, however, is the import of frozen french fries to meet the demand for fast food, especially among a growing urban population. As of 1995, most imports were from Canada, with a smaller volume from the USA (Scott and Maldonado 1998, p. 223). However, this trend could grow to the extent that Peru maintains open markets as required by international trade agreements, and imported products are more cheaply available and/or better suited to urban markets than locally produced potatoes.
Significant research organizations in Peru include (sites in Spanish unless indicated otherwise):
- The Peruvian Government's central institute of agricultural research, Instituto Nacional de Investigación Agraria y Agroindustrial (INIA;)
- Proyecto Conservación In-Situ, a project sponsored jointly by several organizations, dedicated to in situ conservation of crop genetic resources, including potato (in English, the In Situ Conservation Project);
- RedePapa, for information about potato research taking place in several Andean countries;
- Papa Andina, a research project active in Peru, Bolivia, and Ecuador, supported by CIP and the Swiss Agency for Cooperation and Development (COSUDE);
- INCOPA, (affiliated with Papa Andina) intended to enhance commercial market opportunities for potatoes.
Kelly Theisen is the principal contributor to the revised (2006) Peru potato chapter, some sections based on the previous edition by R.E. Rhoades, R.J. Hijmans, and L. Huaccho.
Graham Thiele, Stef de Haan, and Greg Forbes provided information and advice via personal communication.
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