Development, Environment & energy, Social policy, Food & water | Australia, Asia, Southeast Asia, The Pacific, The World

18 September 2019

As Papua New Guinea experiences sustained population growth, its high dependence on village agriculture will struggle to feed multiplying mouths, Bryant Allen writes.

This August, Australia and Papua New Guinea (PNG)’s 27th Ministerial Forum was held in Port Moresby.

As part of this, the governments released a joint communique, part of which announced that the Australia-PNG relationship will be based on “strong democracies for a stable future; close friends, enduring ties; an economic partnership for prosperity; strategic cooperation for security and stability; social and human development; and near neighbours, global partners”.

Conspicuous by its absence is any mention of a major issue confronting PNG – its rapidly growing population.

The total population of PNG has been growing at an average rate of around 2.5 per cent per year since 1966. While 7 million people now, at this rate it will almost double every 30 years.

It is important to note however that – since the 2011 census was deemed a failure by then Prime Minister of PNG Peter O’Neill – this remains a disputed estimate.

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Rapid population growth alone can seriously inhibit progress in a developing country. Services like education and health must expand just as rapidly as the population in order to keep up, making improvement in real terms difficult to achieve.

For PNG, population growth has a specific impact on food production and how it is associated with environmental change. Without serious change, rapid population growth ultimately may threaten long term food security for many rural people.

Despite PNG’s overall size, only 25 per cent of the total land area is used for agriculture. The rest of the country is too wet, too steep, or too high – and therefore too cold – for the production of food. Agriculture has been practised for at least 8000 years in PNG, and so most of the land that is suitable for food production is already in use.

Work by the CSIRO found that between 1975 and 1996 the population increased by 50 per cent, but in contrast, the area of land used for agriculture increased by only 11 per cent, a significant intensification of land use.

This is important because around 85 per cent of all the food consumed in PNG is produced by subsistence agriculture, grown by the villagers who eat it.

Almost no chemical fertilisers are presently used to grow food in PNG. Instead, the nutrients taken from the soil by cropping are replaced naturally by the use of fallows.

Fallows are periods when the land is not cultivated. Unplanted weeds, grasses, shrubs and eventually trees, grow on the fallow garden site. In general, the amount of plant material, or biomass, in a fallow is correlated with the length of time the land has been in a fallow.

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According to research, more than half of the land is left in fallow for more than 15 years and a further 40 per cent for between five and 15 years. Only a small amount of cultivated land is fallowed for less than five years.

It is here that population growth may become an issue. If the area of land suitable for growing food is limited, as it is in PNG, then when the population increases, the land needed to grow the additional food must come from the area in fallow.

The outcome is inevitably shorter fallow times. This causes reduced biomass in the fallows and ultimately poorer soil conditions. Sooner or later, it will lead to lower crop yields.

What evidence is there that this process is actually happening in PNG today?

This is difficult to answer because the study of soil and vegetation conditions over even a 15 year cycle is a major research challenge. What we do know is that villagers respond to these changes by the adoption of practices such as soil tillage, green manure, mounds, and planted nitrogen-fixing trees to maintain soil fertility under shorter fallow times.

Changes in food crops have also occurred. In 1962, sweet potato provided an estimated 45 per cent of total food energy produced in PNG, with banana and sago 16 per cent, and yam 8 per cent. By 2000 these proportions had changed to sweet potatoes 66 per cent, banana 8 per cent, sago 7 per cent, and yam 5 per cent. Two introduced South American crops, cassava and a new taro, now provide 10 per cent of food energy.

A 2014 workshop in Milne Bay found that village participants thought population growth was the primary driver of this change.

There are some positive steps being taken.

The villagers have sought improved garden productivity and family planning as solutions to the growing population.

The adoption of new crops that can be sold for cash has provided some villagers with the opportunity to purchase imported food, tinned fish and meat and rice and flour.

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Imported foods improve diets low in protein and supplement seasonal and periodic shortages of energy. But a 2004 estimate of the value of enough rice imports to just replace PNG produced sweet potato was $2.2 billion.

The CSIRO soils division is to engage with the Australian Centre for International Agriculture Research to look at PNG’s soils and will possibly use agricultural systems identified by research from the ANU, to examine areas where land-use intensity is highest.

In general, though, this growth is raising difficult questions for policymakers.

Australia must engage with PNG on population growth and what can be done. The Australian aid program can be a crucial part of addressing its adverse effects.

In all, a better understanding is needed of PNG’s situation and the way food production systems are critically impacted by population growth. Only then can population growth be prevented from posing a long term threat to PNG’s food security.

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