Sweet potato, sago, banana, yam, taro, Chinese taro, cassava, sugar cane, coconut, Irish potato and corn are the main staple foods eaten by rural villagers in Papua New Guinea (PNG).
Table of Contents
Sweet potato is grown by almost all rural villagers in PNG (99%), the exceptions being people living in a limited number of locations in East Sepik and Western provinces where land is subject to regular flooding. Sweet potato is the most important food for 66% of the rural population and an important food for a further 15% of the rural population. Thus it is the most important food or an important food for more than 80% of the rural population. Sweet potato is especially important for food production at locations above 1500 m altitude. It is also important on Bougainville, New Ireland, New Britain and on coastal and inland areas in Madang, Morobe, Oro, Milne Bay and Central provinces. Sweet potato is grown in a wide range of environments in PNG: from sea level to 2700 m altitude; in locations where the mean annual rainfall ranges from 1000 mm to 6500 mm per year; and on most landforms and soils.
Sweet potato was introduced and adopted in the PNG highlands around 1700 AD. It displaced taro as the most important food in the highlands so that, by the early colonial period (1880–1940), it provided an estimated 40% of food energy from locally grown staple foods. This proportion grew to 66% by 2000 as production expanded.
Sago (Metroxylon sagu Rottb.) is a large palm that grows in swamps and wetland areas. In PNG, sago is produced from planted and wild palms growing in large areas of continuous swamp (swamp sago), and from numerous scattered small areas of palms planted in upland environments (upland sago). Starch is extracted from the palms by a number of techniques, all of which involve cutting the palm down, splitting open the trunk or stripping the outer bark from it, chopping the pith to pulverise it, and leaching the starch from the pith. The starch can be cooked and eaten immediately, or it can be stored for relatively long periods by drying it to a flour or by using anaerobic storage. Sago starch contains 83% carbohydrate. To avoid malnutrition, it is critical that people who have sago as a staple eat additional, nutrient-rich food.
The Mapping Agriculture Systems in PNG (MASP) project, using 2000 National Census figures, found approximately 1.4 million people in PNG — just over one-third of the total rural population — use sago as a food. Twelve per cent of the rural population or 460,000 people eat sago as their most important food, either as a single staple or as a co-staple with bananas or a root crop. Of those who use sago as a staple food, about 184,000 (40%) produce swamp sago and 276,000 (60%) produce upland sago. Thus, upland sago is the most important source of food for 7% of the total PNG rural population. More than half (55%) of these people are located in the foothills of East and West Sepik provinces.
Banana is grown by most rural people (96%), except by those living at very high altitudes. It is the most important food crop for 9% of the rural population. A further 32% of rural people grow it as an important food. It is eaten cooked and as uncooked fruit, depending on the variety and maturity when harvested. More fruit is eaten cooked than uncooked. Banana is grown from sea level to an altitude of 2150 m. There is a large variation in rainfall between locations where it is the most important food. It is an important food in locations with a marked dry season each year and relatively low annual rainfall, such as in coastal Central Province and the Markham and Ramu valleys in Morobe and Madang provinces. It is also an important food in locations with no rainfall seasonality and very high annual rainfall, such as some places in inland Gulf and Western provinces. Banana is also an important food where the rainfall is neither particularly high nor low but is moderately seasonal, such as on the Gazelle Peninsula in East New Britain Province. The relative importance of banana has declined over time as has that of the other Pacific staple food crops (taro, sago and yam) because of the adoption of a number of crops from the Americas, particularly sweet potato, cassava, Chinese taro and corn.
Yam species are grown by 60% of the rural population. Greater yam (Dioscorea alata) is more widely grown than lesser yam (D. esculenta), but greater yam is not the most important food anywhere and is an important food for only 4% of the rural population. Lesser yam is the most important food or an important food for 13% of rural villagers. It is the sole most important food in inland East Sepik Province and the southern part of Western Province. Greater yam is grown up to 1900 m above sea level and lesser yam up to 1550 m, but most production for both species occurs in the lowlands. Yam is usually more important in seasonally dry climates, such as inland East Sepik, but it is sometimes an important crop in locations where rainfall is well distributed throughout the year, such as the northern islands of Milne Bay Province. Total production seems to have increased between 1960 and 2000, but yam’s contribution as a proportion of total staple food energy has declined over this period.
Colocasia taro is grown by most rural villagers (95%) in PNG, but it is now the most important food for only 6% of the rural population, with a further 25% growing it as an important food crop. Despite being grown by many people in most parts of PNG, by 2000 taro was the sole most important food in only a few locations, including the inland Kandrian area of West New Britain Province and most of the Telefomin area of Sandaun Province. Taro is widely grown from sea level to an altitude of 2400 m, although monocultures of taro are not grown above 2200 m. There is a wide range in annual rainfall at these locations (1500 mm to over 7000 mm). In the past, taro was the sole staple food in wetter and less seasonal environments, and where rainfall seasonality was greater it was grown with other staples. Prior to the introduction of sweet potato, Colocasia taro provided an estimated half of food energy from the staple foods. Production has declined since 1940, so that by 2000 it provided only 4% of food energy from locally grown staple foods. The use of taro as a food has been affected by taro blight (Phytophthora colocasiae), which caused a sudden and severe loss of production in some lowland areas after 1940. Production has also been affected by declining soil fertility associated with more intensive land use, virus infection and taro beetle damage.
Chinese taro is grown by more than half the rural population and is the most important food or an important food for 22% of the rural population. It is the most important food on its own or with one other crop in parts of the Baining Mountains of East New Britain Province, on the north and south of the Huon Peninsula in Morobe Province and in the Adelbert Range and Gogol Valley in Madang Province. Chinese taro grows from sea level to 2000 m altitude. It is a more important crop at intermediate altitudes and lower highland locations (500–1500 m altitude) and in places where rainfall is higher and not seasonal. Chinese taro was introduced into PNG in the late nineteenth century. It increased in importance from 1940 until the 1980s and then declined somewhat as production was affected by a root disease, possibly caused by a fungus (Pythium sp.).
Cassava is grown by more than half the rural population, but is the most important food for only 1% of rural people. It is the most important food on its own or with one other crop in some places in West New Britain Province, including the Cape Hoskins and Talasea areas, and in a number of locations in Milne Bay, including the Cape Vogel area and parts of Goodenough Island. In Milne Bay Province, more cassava is produced than any other staple food. Cassava grows from sea level up to 1800 m, but is only an important food in the lowlands. It is an important food in locations with a wide range of rainfall, including weakly seasonal and high annual rainfall, and markedly seasonal and relatively low annual rainfall. Cassava was introduced into PNG in the nineteenth century, but only started to become widely grown after 1950. Production is expanding rapidly, with a threefold increase in its relative importance as a food between 1960 and 2000.
Sugar cane is one of the most widely grown food crops in PNG, with 99% of the rural population growing it. People suck the juice from the chewed cane. Production estimates are not available that are comparable with estimates for the other staple foods. The 1996 Household Survey estimated production as 190 000 tonnes of cane per year or 35 kg/person/year. Sugar cane is grown almost everywhere in PNG up to its altitudinal limit at 2600 m. There are no reliable data indicating trends in production over time, but this is likely to have increased with population growth.
Coconut is an important food for 36% of the rural population. It is widely grown on islands, coastal locations and some inland locations on the New Guinea mainland up to 950 m above sea level. No reliable data are available for changes over time. However, it is likely that more coconut became available for consumption following widespread planting of palms for copra production from the late 1800s.
Irish potato is grown by 16% of the rural population. It produces tubers between 700 m and 2750 m altitude in PNG. It is most commonly grown for subsistence purposes above 2000 m but is also grown for sale in parts of the highlands. Irish potato was introduced into the highlands in the 1930s. Production increased for both subsistence and sale after about 1970, but declined following an outbreak of potato late blight (a fungal disease) in early 2003.
Corn (maize) is not an important food compared with the main root crops, banana and sago. Nevertheless, it is grown by 94% of the rural population. It grows from sea level up to 2450 m. It is often more significant in seasonally dry locations, such as the Henganofi area in Eastern Highlands Province, where it produces food about three months after planting, before other crops mature. Production in the highlands is markedly seasonal. Corn was introduced into PNG in the nineteenth century. It has increased in importance since then, particularly since the introduction of superior varieties after 1970.
Minor root crops
A number of minor root crops are eaten, including Queensland arrowroot and three species each of yam and taro. The quantities grown and the number of people growing these crops are generally small. Swamp taro
is the only minor root crop that is a most important food or an important food crop. It is the most important food on three atoll groups in Bougainville Province and important on a few small islands, such
as those west of Manus Island.
Other grain crops
Rice is grown by villagers in a number of locations. It has been and continues to be promoted widely, but only a very limited quantity is grown. Experimental plantings of a number of other grain crops including wheat, oats and buckwheat have been made, but these crops have not been adopted by villagers.