Journal article
Use of on-ground gamma-ray spectrometry to measure plant-available potassium and other topsoil attributes
Australian Journal of Soil Research, Vol.37(2), pp.267-278
1999
Abstract
The incidence of potassium (K) deficiency is increasing in crops, pastures, and forestry in south-western Australia. Although soil K can be measured using soil sampling and analysis, γ-ray spectrometry offers a potentially cheaper and spatially more precise alternative. This could be particularly useful in precision agriculture, where inputs are applied according to need rather than by general prescription.
In a study of topsoils near Jerramungup, Western Australia, strong relationships (r2 = 0·9) were found between on-ground counts of γ-rays derived from 40K (γ-K) and both total K and plant-available K. The success of γ-ray spectrometry in predicting available K relied on a strong relationship (r2 = 0·9) between total K and available K which may not hold in all areas. Although the relationship between γ-K and available K held over the range of 36–1012 mg/kg, crop response to K fertilisers is only expected when the available K content is <100 mg/kg. Estimates of available K from γ-K were unreliable at this lower end of the regression curve. Separate analysis with a subset of the data with available K <100 mg/kg showed a poor relationship between γ-K and available K (r2 = 0·05; d.f. 11). The usefulness of γ-ray spectrometry may therefore be restricted to defining areas where response to fertiliser K may occur, and where further soil sampling and analysis are required to predict the fertiliser requirement.
Strong relationships (r2 = 0·9) were also found between γ-K and a range of other soil attributes, including clay, silt, and organic carbon content. These relationships depended on the locally strong relationship between total K and these soil attributes. Since such relationships do not hold everywhere, the utility of γ-ray spectrometry will likewise be limited. Site-specific calibrations are required if γ-ray spectrometry is to be used for soil property mapping.
Details
- Title
- Use of on-ground gamma-ray spectrometry to measure plant-available potassium and other topsoil attributes
- Authors/Creators
- M.T.F. Wong (Author/Creator)R.J. Harper (Author/Creator)
- Publication Details
- Australian Journal of Soil Research, Vol.37(2), pp.267-278
- Publisher
- CSIRO Publishing
- Identifiers
- 991005546031507891
- Copyright
- © CSIRO 1999
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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Source: InCites
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- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.45 Soil Science
- 3.45.1109 Soil Mapping
- Web Of Science research areas
- Soil Science
- ESI research areas
- Environment/Ecology