R. Michael Bourke

The sustainability of Papua New Guinea agricultural systems: the conceptual background

Abstract Papua New Guinea offers an opportunity to study the Intensification and sustainability of village agriculture under the pressures of demographic change and social and economic development. This paper describes research investigating the process of agricultural intensification. Theories of intensification suggest the process is associated with increasing population, or with increased production for social purposes, or both. Intensification brings about changes that must be overcome by innovation. Innovation may demand temporary or permanent increases in labour, and changes in the social relations of production, but intensification without innovation is likely to lead to land degradation. A tension exists between the environment, social organization, production and the adoption of innovative techniques, which may determine whether intensification is sustainable. The research is presently identifying, mapping and systematically describing agricultural systems. Preliminary results suggest intensification is positively associated with altitude, sweet potato (lpomoea batatas) cultivation, and with a number of innovative agronomic techniques.

Food, coffee and casuarina: an agroforestry system from the Papua New Guinea highlands

An agroforestry farming system is described from the Papua New Guina highlands (1400 to 2100 m) that has been developed by village growers since about 1960 and has expanded rapidly since about 1970. Major components of the system are numerous species of annual and perennial food crops (especially bananas), arabica coffee andCasuarina oligodon. It provides food, a cash crop and timber for construction and fuel. It is likely that returns on labour inputs are very favourable, but no formal assessments have been made. Evaluation of the system as a whole, and research on certain key components (casuarina ecology, banana cultivars, timing of operations) are suggested as high priority areas for systematic studies.

Intensification of Agricultural Systems in Papua New Guinea

This paper provides an overview of the ways in which villagers have intensified agricultural systems in Papua New Guinea, focusing on the last 60 years. The intensification techniques used by villagers include: adoption of more productive staple crops, in particular sweet potato, cassava, Xanthosoma taro, Solanum potato and maize; adoption of more productive cultivars, especially of banana and sweet potato; shortening the fallow period; extending the cropping period; certain soil fertility maintenance techniques, other than natural regrowth fallows (composting, managed tree fallows, especially using casuarina, a legume/root crop rotation, and soil erosion control); and some other intensification techniques including soil tillage, drainage, construction of garden beds, garden segregation, mounding and irrigation. People often use more than one technique and the techniques used vary between the major agricultural zones. The adoption of new food crops and more productive cultivars of existing food crops has facilitated many of the other changes, particularly longer cropping periods and shorter fallow periods.