The predominance of subsistence agriculture in Papua New Guinea (PNG) highlights the importance of food security. Small holders have generally learnt to manage the localised shortages of food that occur regularly through the use of families and friends and purchasing food from the sale of cash crops such as coffee and potatoes. It is the large scale shortages of food that occur irregularly that threaten human health and survival such as during the 1997 El Nino.
Extreme events (droughts and floods) have significant impacts on agricultural production and natural resource management. On a national scale droughts are associated with El Niño's and wet events are associated with La Niña's. There are local and regional differences that are important to understand.
During extreme events that cause widespread food shortages the PNG government has relied upon food aid (national and international) and more recently on small holders’ self-reliance to purchase imported food. It is the more remote and isolated rural communities that are most vulnerable because of their poor access to food distribution points and markets to sell produce from cash crops.
Sweet potato is the dominant staple food and is therefore the most important crop in PNG. Over 60% of the rural population depend on it as their main food source. About 75% of annual sweet potato production is grown in the highlands. Climatic extremes, particularly high soil moisture, droughts and frosts are among the main constraints to production. Although sweet potato is relatively drought tolerant, excessive wet periods during tuber initiation followed by drought during tuber development significantly reduce tuber production, and the low yields may not be discovered until harvest. Repeated frost also significantly reduces tuber yield. Being a crop grown below ground, the yields of sweet potato are not known until harvest time. A climate integrated sweet potato production model can help predict yields some months in advance which will help with management of the impacts from these extreme events.
Smallholders produce about 85% of the coffee grown in PNG making it a valuable cash crop for many villages. It is grown mainly for export and represents ~40% of all agricultural exports. The production of coffee is triggered by natural cycles of dry and wet conditions however extreme wet periods in poorly drained soils have as large a negative impact on production as drought, particularly during cherry ripening and development when large quantities of nutrients and water are required for high yields. A climate integrated model for Robusta coffee in Vietnam has been developed, but there is nothing for Arabica coffee which is the main species grown in PNG.
This project will use the potato model in APSIM as the framework and data from Qld and PNG to parameterise a climate driven sweet potato model. Another aspect could be to develop an Arabica coffee model using PNG coffee data.

Professor Roger Stone

• Assoc Prof David Cobon

• International Centre for Applied Climate Sciences

• Agriculture, Land and Farm Management
• Atmospheric Sciences

• Doctor of Philosophy (DPHD)
• Master of Research (MRES)