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Mapping rice yield and its fertilizer response at provincial-scale in Takeo, Cambodia

Bell, R.W., Pracilio, G., Cook, S., Ros, C. and Seng, V. (2006) Mapping rice yield and its fertilizer response at provincial-scale in Takeo, Cambodia. Cambodian Journal of Agriculture, 7 . pp. 36-44.

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Our objective was to identify responsive areas for nitrogen (N), phosphorus (P) and potassium (K) fertiliser use on rice (Oryza sativa L.) within Takeo province from trial results obtained at 2336 sites. Regression tree analysis identified in order of decreasing importance the following factors which explained the variation in yield from on-farm experiments: season, location, fertiliser, soil type. Semi variograms of the same data set indicated that a maximum spread of 12 km in datum points was required to map yield across the province. Separating the results into N response classes decreased the maximum spread of datum for mapping to only 8 km. The maps generated indicated areas in which response to fertiliser is more or less likely. Whereas P responses were predicted to be relatively uniform across the province, N and K responses were more varied. Results suggest a very strong positive response to N, particularly on the central-west of the province. They also suggest negative effects of high N rates on the most fertile soils (Kbal Po, Krakor) in the east of Takeo, and in the Prateah Lang and Koktrap soils in the flooded areas of the south east of Takeo. At the provincial scale, the maps identified areas that can be used to target extension effort to where it is likely to be most effective, and areas where further research is needed to clarify reasons for poor responses. This should enhance the strategic planning capability for delivery of extension services and fertiliser inputs.

Publication Type: Journal Article
Murdoch Affiliation: School of Environmental Science
Publisher: Cambodian Agricultural Research and Development Institute.
Copyright: © Cambodian Agricultural Research and Development Institute.
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