Invasion of Piper aduncum in the shifting cultivation systems of Papua New Guinea: Foreword by David Pimentel
Hartemink, A.E. - \ 2006
Wageningen : ISRIC - World Soil Information - ISBN 9789081062817 - 234
piper aduncum - invasies - zwerflandbouw - ecologie - invasie - papoea-nieuw-guinea - piper aduncum - invasions - shifting cultivation - ecology - invasion - papua new guinea
Piper aduncum, a shrub native to Central America, arrived in Papua New Guinea before the mid-1930s possibly from West Papua. From the 1970s it started to dominate the secondary fallow vegetation in many parts of the humid lowlands. It invaded grassland areas and it also appeared in the highlands up to 2100 m. The combination of its small and abundant seeds, its high growth rates, and the accidental or intentional spreading has resulted in its presence in most provinces of Papua New Guinea. The spread will continue.
Sweet potato yields and nutrient dynamics after short-term fallows in the humid lowlands of Papua New Guinea
Hartemink, A.E. - \ 2003
Netherlands Journal of Agricultural Science 50 (2003)3-4. - ISSN 0028-2928 - p. 297 - 319.
ipomoea batatas - zwerflandbouw - verbeterde braak - piper aduncum - gliricidia sepium - imperata cylindrica - gewasopbrengst - papoea-nieuw-guinea - bodemvruchtbaarheid - voedingsstoffenbalans - zoete aardappelen - sweet potatoes - ipomoea batatas - shifting cultivation - improved fallow - piper aduncum - gliricidia sepium - imperata cylindrica - soil fertility - nutrient balance - crop yield - papua new guinea - ipomoea-batatas - imperata-cylindrica - gliricidia-sepium - piper-aduncum - use efficiency - nitrogen - soil - cultivation - growth - fertilization
Shifting cultivation is common in the humid lowlands of Papua New Guinea but little is known about the effect of different fallows on sweet potato (Ipomoea batatas) yield and nutrient flows and pools in these systems. An experiment was conducted in which two woody fallow species (Piper aduncum and Gliricidia sepium) and a non-woody fallow species (Imperata cylindrica) were planted and slashed after one year. Sweet potato was grown for two consecutive seasons (1 year) after which the fallows and yields were compared with yields from continuously cropped plots. The experiment was conducted on a high base status soil (Typic Eutropepts). In the first season, marketable sweet potato yield after piper and imperata was about 11 t ha-1 but yields after gliricidia and under continuous cropping were significantly lower. Vine yield was similar for the continuously cropped plots and for the sweet potato after piper and gliricidia, but significantly lower than after imperata. The effects of the fallows on sweet potato yield lasted only one season. In the second season after the fallow, sweet potato yields were higher, which was contributed to lower rainfall. Nutrient budgets showed that the three fallow species (piper, gliricidia and imperata) added insufficient amounts of nitrogen, phosphorus and potassium for the removal of these nutrients by two consecutive seasons of sweet potato. From a yield point of view there seems no benefit in having a nitrogen-fixing fallow species like Gliricidia sepium in sweet potato based systems on high base status soils.