Understanding soil processes in oil palm plantations using an agricultural system model

Conference Contribution ResearchOnline@JCU
Huth, Neil I.;Nelson, Paul N.;Banabas, Murom;Webb, Michael J.
Abstract

Many soil processes are related to cycles of water, carbon and nitrogen. Agricultural systems models are regularly employed to study such processes because of their ability to integrate and explore a range of environmental and crop management factors. However, no such model is currently available for oil palm production systems. We developed one within the Agricultural Production Systems Simulator (APSIM) framework and tested it using data from nitrogen fertiliser trials across a range of environments within Papua New Guinea. The model captured key trends in canopy development, biomass production and yield of fresh fruit bunches due to plantation age, climate and nitrogen management. The model was used to estimate the effects of plantation age and nitrogen fertiliser rates on carbon and nitrogen cycling processes in soil at one site. Soil carbon content increased during the immature phase and then stayed constant (with high fertiliser rate) or declined (zero fertiliser) during the mature phase. During the immature phase there were substantial leaching losses of NO3, and gaseous emissions of N2O and N2 from the soil, presumably driven by the inputs of nitrogen from the previous oil palm crop residues and from nitrogen fixation by the leguminous cover crop. During the mature phase, nitrogen losses increased with increasing fertiliser rate. The model is a useful tool for exploring possible effects of environmental and management factors on soil processes. Simulations suggested that the immature phase is an important and understudied period for nitrogen losses and soil organic matter accumulation.

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Workshop on Applications of Radio Science 2008 Conference

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1

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Gold Coast, QLD, Australia

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ICOPE

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