Computers and Electronics in Agriculture

31 (2001) 211–212

EditorialAdvances in soil instrumentation

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The study of soils by scientists and engineers has always involved a heavydependence on instrumentation for the assessment of both physical and chemicalproperties. However, in recent years the requirement for improved soil measure-ment instrumentation, sensors and techniques, has been driven by two additionalfactors. These are firstly, the increased demands of improved agricultural manage-ment practices, notably ‘precision agriculture’; and secondly, an increased aware-ness of the importance of soils within the natural environment, notably with respectto salinity and soil erosion. Both changes have led to enhanced measurementrequirements in all aspects of soils measurement.

The implementation of improved agricultural and environmental managementsystems require scientists and engineers to achieve a better understanding of soilphysical and chemical processes at increasingly small scales. This has led to arequirement for sensing techniques with increased measurement precision anddiscrimination between measurands, and (in the field) improved spatial discrimina-tion. Likewise in the laboratory there is continuing pressure for the refinement andautomation of existing as well as novel techniques. Fortunately these changingmeasurement requirements have occurred during a period of continued advance-ment in electronic and computing technologies. As a result, we can detect evensmaller signal perturbations and utilise minor transduction effects, and also copewith the increased volumes of data produced. Hence, it is not surprising that thereis renewed interest and a sense of opportunity within the field of soilinstrumentation.

As we enter the new millennium, certain techniques and technologies appear tobe reaching maturity. Techniques involving electromagnetic interactions such astime domain reflectometry (TDR) are now in common use with a range ofcommercial instrumentation available and the underlying science now well under-stood. In contrast, other technologies are emerging as potentially useful in soilmeasurements and are starting to make the transition from research laboratory tofield. One such example is the application of advanced chemical sensors such asion-specific field effect transistors (ISFETs). Others, such as biosensor applications

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and responses to near infra-red (NIR) radiation (capable of detecting organic matter),are actively being pursued and hold promise for the immediate future.

This special issue of ‘Computers and Electronics in Agriculture’ presents a smallcross-section of the current work in the field of soil instrumentation. It was conceivedto collect together and promote the soil technical instrumentation issues that wouldnot normally be specifically reported in soil journals. This special issue also highlightsthe truly international nature of this work, with contributions from researchers innorth and South America, Europe, Japan and Australia.

Commencing this special issue, Noborio presents a major review of time domainreflectometry (TDR) and its application to the measurement of both soil water contentand soil salinity (as electrical conductivity, EC). This paper draws together therelevant theory and applications practice and includes the critical topic of TDR probeconfiguration and installation. Sudduth et al. report on the accuracy of non-contactelectrical conductivity sensing in the field, as applied to the requirements of precisionagriculture. Bristow et al. describe a small-scale ‘multi-needle’ probe capableof simultaneously sensing a range of soil physical properties —temperature, thermal diffusivity, volumetric heat capacity, thermal conductivity,volumetric water content and bulk electrical conductivity — which can provide finespatial resolution in field applications. Artigas et al. are concerned with sensingchemical properties and present promising results in the direct in-soil application ofion-specific field effect transistors (ISFETs). Results for the measurement of pH andcalcium, potassium and nitrate ionic concentrations are presented. Finally two papersreport developments of laboratory technique, both focusing on the automation ofassessment of critical soil physical properties. Naime et al. have further developedthe determination of particle size distributions by gamma-ray attenuation; and Lochhas refined the settling column technique for soil aggregation and sediment mobilityassessment, information which is fundamental to the determination of soil erodibility.

The co-Guest Editors are grateful for the support and active assistance of manypeople in the assembly of this special issue. In a cross-disciplinary field such as appliedinstrumentation, peer review is almost always multifaceted and the Guest Editorsappreciate the diligence and helpfulness of the reviewers. Particular thanks in thisregard are due to the Editors-in-Chief of this journal, Drs Dan Schmoldt and SidneyCox.

Nigel Hancocka, Steven RainebSeptember 2000a Faculty of Engineering and Sur6eying

Uni6ersity of Southern QueenslandToowoomba, Queensland 4350

Australiab National Centre for Engineering in Agriculture

Uni6ersity of Southern QueenslandToowoomba

Queensland 4350Australia

E-mail: hancockn@usq.edu.auE-mail: raine@usq.edu.au.