• Charles Sturt University economic assessment research of a sweet potato production project in Papua New Guinea (PNG) contributes to food security and improved livelihoods of small-scale landholding farmers
• The economic assessment found the research experiment conducted to control pest and disease damage has significantly improved marketable sweet potato yield and storage root yield which doubled farmers’ net income
• These had significant positive influence on the farmers’ perception towards adoption of the new technology which was the subject of the experiment

Research by a Charles Sturt University academic and student is helping improve the production of sweet potato, one of the major food crops grown in Papua New Guinea (PNG).

The economic assessment research was conducted by Senior Lecturer in Agribusiness Dr Richard Culas (pictured, inset) in the Charles Sturt School of Agricultural, Environmental and Veterinary Sciences and postgraduate student Mr Coleman Pombre in the then- Master of Sustainable Agriculture (now the revised new Master of Agriculture).

Dr Culas is also a member of the Charles Sturt Gulbali Research Institute of Agriculture, Water and Environment. Mr Pombre was engaged in the PNG project and Dr Culas supervised his master’s dissertation.

Sweet potato (Ipomoea batatas, at left) is a major staple food crop in PNG and is grown extensively in the high-altitude Highlands as a subsistence food crop by smallholder farmers, and sweet potato crops are also developing into commercial production for cash income.

“PNG’s agriculture is mostly rural-based and largely remains as subsistence agricultural farming systems with very few modern farming practices and resource inputs,” Dr Culas said.

“This has hindered further improvements in PNG agriculture and improving rural people’s livelihoods.”

Dr Culas said the research project that his study assessed aimed to determine whether the production of sweet potatoes can be improved because it is one of the major food crops grown mainly by the smallholding farmers for their own use as well as for marketing (cash income).

“Crop attack by pests and diseases remains a major challenge, and most PNG farmers do not practice active management of pests and diseases, which has a significant impact on crop yield and farmers’ income,” he said.

“Few farmers have opted to use ‘cultural practices’, but these methods are ineffective and expensive.”

In three different zones in the PNG Highlands (Western Highlands, Simbu, and Eastern Highlands) the researchers trialled an alternative intervention technology ─ Pathogen Tested (PT) seeds ─ as a part of Integrated Pest and Disease Management (IPDM) technology and compared the results with the Conventional Practice (CP).

“Results showed that implementation of the pathogen-tested practice significantly improved marketable sweet potato yield when compared to the conventional practice,” Dr Culas said.

“Our assessment found that the improvement in storage root yield resulted in doubling the net income for the farmers.

“Both the yield and quality of storage roots had significant influence on the farmers’ perception towards adoption of the IPDM technology.”

Dr Culas said that although the costs per hectare for the PT method were higher than the CP method, the net income was comparatively high for the PT method; this indicates that the use of pathogen tested planting materials is economically viable for PNG rural farmers.

“The adoption of the PT method can be promoted in the country for improving yield, quality of production, and to enhance farm income and rural livelihoods,” he said.

“However, the ability to cultivate the PT sweet potato planting material will only be harnessed if the clean planting material is readily and easily accessible for use by farmers.

“We suggest the use of local varieties for cleaning and release to the farmers because local consumers have shown a preference for the taste and texture of the local varieties.”

Dr Culas said farmers’ education level, knowledge of the PT method and access to extension services are likely to have more influence on the adoption of the PT technology.

“Thus, any policy framework development aimed at enhancing adaptive capacity of the farmers should also consider these factors,” he said.

“A further study in this research context can be relevant to assess the effectiveness of the PT method following a few cropping cycles or the number of days after the planting.

“Because the yield can start to drop and diseases start to emerge again (with the possibility of a decrease in the marketable yield), this would mean repeated cleaning and screening for virus diseases is necessary to maintain disease-free planting materials.

“Thus, a follow-up study should be conducted in the same areas where farmers have already adopted the PT method, to monitor and assess disease incidents and yield changes.”

The research, ‘Assessing socioeconomic impact of pathogen tested and conventional practice sweet potato production in the highlands of Papua New Guinea’, was recently published in the Journal of Agriculture and Food Research (Volume 14, December 2023), and has been  available online since 25 June 2023.

Dr Culas and Mr Pombre acknowledge the significant contribution of the National Agricultural Research Institute (NARI) in PNG for providing field trials yield data, and the Fresh Produce Development Authority (FPDA) in PNG, for facilitating the socioeconomic farm survey conducted in the study area during 2019–2020.

The authors also greatly appreciate the support provided by the Project Leader Professor Geoff Gurr, and the project team members, during the course of this study.