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The use of an optical fibre long period grating (LPG) as a soil moisture sensor is reported. Characterization of the device in both clay and sandy soils revealed a sensitivity to moisture levels in the range 10-50%, and the results were compared with the output from a Theta probe, the standard soil moisture sensor, which measures the impedance of the soil.

Background Phosphorus (P) is the limiting nutrient in many mature tropical forests. The ecological significance of declining P stocks as soils age is exacerbated by much of the remaining P being progressively sequestered. However, the details of how and where P is sequestered during the ageing in tropical forest soils remains unclear. Results We examined the relationships between various forms of the Fe and Al sesquioxides and the Hedley fractions of P in soils of an incipient ferralitic chronosequence on an altitudinal series of gently sloping benches on Green Island, off the southeastern coast of Taiwan. These soils contain limited amounts of easily exchangeable P. Of the sesquioxide variables, only Fe and Al crystallinities increased significantly with bench altitude/soil age, indicating that the ferralisation trend is weak. The bulk of the soil P was in the NaOH and residual extractable fractions, and of low lability. The P fractions that correlated best with the sesquioxides were the organic components of the NaHCO3 and NaOH extracts. Conclusions The amorphous sesquioxides, Feo and Alo, were the forms that correlated best with the P fractions. A substantial proportion of the labile P appears to be organic and to be associated with Alo in organic-aluminium complexes. The progression of P sequestration appears to be slightly slower than the chemical and mineralogical indicators of ferralisation.

The creation and use of ontologies has become increasingly relevant for complex systems in recent years. This is because of the growing number of use cases that rely on real world integration of disparate systems; the need for semantic congruence across boundaries; and, the expectations of users for conceptual clarity within evolving domains or systems of interest. These needs are evident in most spheres of research involving complex systems but they are especially apparent in infrastructure and cities where traditionally siloed and sectoral approaches have dominated undermining the potential for integration to solve societal challenges such as net zero; resilience to climate change; equity and affordability. This paper reports on findings of a literature review on infrastructure and cities ontologies and puts forward some hypotheses inferred from the literature findings. The hypotheses are discussed with reference to literature and provide avenues for further research on (1) belief systems that underpin non top level ontologies and the potential for interference from them; (2) the need for a small number of top level ontologies and translation mechanisms between them; (3) clarity on the role of standards and information systems upon the adaptability and quality of datasets using ontologies. We also identify a gap in the extent ontologies can support more complex automated coupling and data transformation when dealing with different scales.

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