Links

Dave and Virginia Askin support an association of development workers in Papua New Guinea.

Dave maintains a personal blog

Dave is supporting the PNG Church Partnership Program and their on-line library and project management system. There is currently a heap of thinking to be done, as the program has entered a second phase, with new design.

Christchurch city has purchased Kilu Consulting software to manage a Neighbourhood Support system.

Alfred Hartemink, a colleague from PNG days at the University of Technology- PNG has an excellent set of resources on his web site.

He had particular interests in soil fertility and management of fallow land.

For example- here is an abstract from one of his papers – watch out he uses the technically appropriate but unhelpful ‘Mg’ instead of the simpler and more farmer friendly measure we know as tonnes (1,000 kg).

Biomass and nutrient accumulation of Piper aduncum and Imperata cylindrica fallows in the humid lowlands of Papua New Guinea Alfred E. Hartemink
International Soil Reference and Information Centre (ISRIC), PO Box 353, 6700 AJ Wageningen, The Netherlands.
from – Forest Ecology and Management 144 (2001) 19:32

Shifting cultivation with short fallow periods (<3 years), is an important form of land use in the humid lowlands of Papua New Guinea. The secondary forest vegetation is dominated by the shrub Piper aduncum which originates from South America, and Imperata cylindrica grasslands in areas where annual bush fires are common. No information is available on the rate of biomass and nutrient accumulation of these two fallow types. Plots with P. aduncum and I. cylindrica were planted on a Typic Eutropepts and sampled every 3 months for 23 months to assess above ground biomass and nutrient content. Total biomass of imperata was slightly higher than that of piper during the first year, but remained around 23 Mg dry matter (DM) /ha in the second year. Above ground biomass of piper increased linearly, and reached 48 Mg DM /ha at 23 months when three-quarter of the biomass consisted of wood. Growth rates of piper were on average 69 kg DM ha per day, and increased with higher rainfall. Nutrient content of imperata was 100 kg N, 12 kg P, 62 kg K, 64 kg Ca, 40 kg Mg and 9 kg S per ha at 23 months. The concentration of K and Ca was high in piper leaves but declined over time. At 23 months, piper had accumulated 222 kg N, 50 kg P, 686 kg K, 255 kg Ca, 75 kg Mg, and 24 kg S per ha. More than half of the P, K, Ca and Mg was found in the stem (wood) which is removed from the field and used as firewood when farmers slash the fallow. Piper biomass (excluding wood) returned about three times more K to the soil than imperata, but differences between total P and S contents were small. For the accumulation of biomass and nutrients, imperata fallows should not exceed 1 year. Piper accumulated large amounts of biomass and nutrients, particular K, which is an important nutrient for root crops that dominate the cropping phase in the shifting cultivation systems of the humid lowlands.

For those unfamiliar with the information here- Piper is a non-leguminous shrub/small tree and Imperata is a rhizomatous weed grass, with very very low value for animal feed. It is used by villagers as roofing material. As a rhizomatous plant it is very resistant to fires and dominates areas where fires are common. It does not tolerate shade and lack of fire. Clearly controlling fire is important as a means of allowing a shrub based fallow to develop that provides approximately twice the nutrients that the grass fallow provides.

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