Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

A method for non-invasive sensing of soil structure and the mechanical strength of soil would permit better decisions about appropriate soil management practices. The lack of suitable methods to measure soil physical characteristics directly that are relevant to crop growth and soil environmental function (e.g. absorption of high intensity rainfall) are barriers to the development of approaches for sustainable soil management. Soils may be regarded as partially-saturated porous media. The acoustical properties of air-filled porous media have been studied widely in various contexts. Models for these properties incorporate parameters related to the frame elasticity and the pore structure. The most widely-used model, Biot theory predicts that such media support two kinds of coupled compressional waves, sometimes called Type I and II waves, and a shear wave. The Type I and shear waves travel mainly through the solid matrix and involve interactions between particles. They are equivalent to the P- and S- waves induced by direct mechanical excitation, for example during a seismic refraction survey. The Type II wave travels mainly through the fluid-filled pores being attenuated by viscous friction and thermal exchanges. It is dominant during acoustic excitation i.e. from sound sources above an unsaturated soil surface since the primary path for sound into the soil is through the pores connected to the surface. Recently it has been demonstrated that the P-wave velocity in soil is highly correlated with the internal stress in a soil. This suggests that P-wave velocities determined remotely from non-invasive acoustic-seismic probing can be used to measure mechanical stress in soil and hence its resistance to root elongation. Furthermore measurements in the laboratory and in instrumented pits outdoors have shown that the velocity and attenuation of sound in soil is related to soil density, water content, matric potential and porosity. The applicants (Attenborough and Taherzadeh) have developed a model (PFFLAGS) to predict the interaction of sound with layered soils, from sources above or within the soil that takes into account both soil mechanical and structural properties. By applyng this model to a combination of acoustic measurements using probe microphones and seismic measurements using geophones it has been found to be possible to obtain values of several soil parameters in reasonable agreement with independently measured values. Of course techniques using buried microphones and geophones are invasive. There remains a need to develop non-contact non-invasive acoustical techniques and to extend them to encompass the determination of moisture content. In this project we propose to investigate the conjunctive use of microphone measurements of reflection from the soil surface of sound from a point source (loudspeaker) and scanning Laser-Doppler Vibrometer (LDV) measurements of the seismic surface response to such insonification.We propose to develop the theory and practical knowledge needed to deduce permeability (a physical property of soils that depends strongly on the number and connectivity of macropores), moisture content and the internal stress in soil and to map these quantities as a function of depth. The proposed technique will serve as a prototype for subsequent engineering development of systems for automated data acquisition and processing in the field.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

In order to meet the global targets for greenhouse gas (GHG) emissions, measurements of the effects of land use and land management practices on GHG emissions are increasingly needed, with a strong and growing requirement for new technologies to enable these measurements. Resulting from previous NERC funding, researchers and engineers at the University of York (UoY) have developed a novel technology, SkyLine2D, which overcomes many of the problems inherent in the current technologies used to monitor terrestrial GHG fluxes. Using the unique approach of suspending a single mobile chamber above the ground, SkyLine2D overcomes many of the limitations of existing, small ground-based auto-chamber systems, which are extremely expensive, inflexible in use, have a heavy site impact and are unable to measure over many vegetation types. The aims for this Follow-on Fund project are to make key technical developments, whilst obtaining relevant IP protection and product certification, that will turn SkyLine2D into a viable commercial product. Finance from the Follow-on Fund grant would be used to further develop SkyLine2D in order to be able to carry, or work with, all major brands of GHG analyser, as well as to provide an independent on-board carbon dioxide monitor. We also need to make improvements to the existing prototypes in terms of data logging and supporting software. Although we already have quite a number of customers interested in buying SkyLine2D we are unable, at present, to sell the system because of these final technical developments whiuch we need to make. Equally important is the requirement for appropriate electrical and mechanical certification before we are allowed to sell the equipment to customers around the world. The vision is for the establishment of a small University spin-out SkyLine company based in York, employing several engineers and scientists, with associated sales and administrative staff, selling SkyLine2D GHG monitoring platforms for use throughout the world. The immediate obvious benefit is to provide local employment, but also to facilitate the collection of important GHG emission data to assist in developing policies for land use management which limit GHG emissions; the equipment could be a vital tool in our search for management strategies for reducing the global atmospheric GHG burden.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.