Influence of soil nitrogen fertilisers on soil acidification in Papua New Guinea
Conference Contribution ResearchOnline@JCUAbstract
Soil acidification is a worldwide concern with many cropping systems where nitrogen fertilisers are used. Inorganic N fertilisers are generally used to improve and maintain high yields especially with oil palm, however little is known on their effects on soil acidification in tree crops especially oil palm cropping systems. This study looked at the effects of different sources of N fertilisers on soil pH and suggests strategies to sustainably grow oil palm in Papua New Guinea. Soil samples were collected in a grid designed from a nitrogen fertiliser trial that has been receiving five different N fertiliser types for more than eight years. The palms were receiving nitrogen at 0, 420, 840 and 1680 g N/palm/year. Soil pH was measured for composite samples for all the plots and individual grid points for two of the plots that received the highest AMC rates. The effect of N fertiliser types and the rates significantly (p<0.001) reduced soil pH but the effects reduced with depth. At the highest N rate, AMC had the most effect in reducing pH to depths greater than 90 cm while urea had the least. However at the normal N rates, pH was reduced by 0.2 – 0.4 units. pH was highly variable between 3.86 and 6.87 at different grid points and was significantly different (p<0.001) between the points. Soil acidification at different grid points was a function of N fertiliser management. Alternating use of different N sources and use of empty fruit bunches are recommended to minimise acidification rates.
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Publication Name
Workshop on Sustainable Management of Soil in Oil Palm Plantings
Volume
144
ISBN/ISSN
1038-6920
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Pages Count
1
Location
Medan, Indonesia
Publisher
Australian Centre for International Agricultural Research
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Canberra, ACT
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