Dr Cameron Grant

Teaching Interests

Introductory soil science

I teach part of a 1st year course called Soils & Landscapes with Annie McNeill (coordinator) and Ron Smernik. This is a 'soup to nuts' course about the basic principles of soil science, including:

• Function & significance of soils
• Soil formation processes & why Australian soils are so fragile
• Classification of Australian soils
• Primary particles and their effect on soil texture & structure
• Soil organic matter, soil organisms, nutrient cycling in soils
• Soil colloids & their influence on cation exchange & soil chemistry
• Soil acidification: causes, consequences & management,
• Atmospheric processes, and inputs/outputs/storage of soil water
• Fertilizers, their role in soil fertility, & their management,
• Salinity: causes, consequences, measurement & management,
• Soil erosion: causes, consequences & management,
• Subsoil fertility: problems & management,

The practical classes are pretty basic but students enjoy them. We observe soils in the field, learn how to hand-texture soils, use the Australian Soil Classification and interpret nutrient budgets. A field trip and a consultants report add broader context to the material taught. The course is offered at Waite campus and the field trip is part of an extensive 4 day tour of South Australian agriculture.

Level 2 soil science

I coordinate a 2nd year course called Soil & Water Resources, in which lectures and practical classes are given at the Waite campus and repeat-lectures are given at the North Terrace campus. We cover:

• Soil physical properties, soil texture, clay minerals, soil organic matter, particle density, structure, bulk density, porosity, aeration, temperature
• Significance of soil water, soil water content & its measurement
• Soil water potential, soil water retention & its measurement, retention curves, plant-available water
• Water movement in soils, factors affecting it, infiltration, hydraulic conductivity, tortuosity, evaporation; influence of texture & structure
• Soil variability and sampling; soil fertility & chemistry
• Water quality, irrigation water
• Management & conservation of soil
• Nitrogen & phosphorus in soils
• Soil organic matter & roots
• The rhizosphere & nutrient cycling in the Australian environment.

The practical classes involve some field work but are mainly based in the lab, where students measure soil biological, physical and chemical properties, as well as the properties of water to be used for various purposes. This is a pretty popular course, which usually attracts about 100 students.

 Level 3 soil science

I teach in (and/or coordinate) a 3rd year course at the Waite Campus: "Soil and Water: Management and Conservation". This is a survey of the catalogue of woes betiding Australian soils and it covers the basic chemical and physical principles responsible for the problems and how to manage them. We also focus on the theory and measurement of water content, potential and movement of water in soils. Our motto is "if you can't measure or calculate it, you probably don't understand it and you certainly can't manage it well!", so the practical classes are fun and we do lots of calculations. Ron Smernik and Wayne Meyer teach this with me.  

We generally get good reviews from the students on this course, particularly after they've been in the workforce for a while. The practical classes are heaps of fun - we use rainfall simulators, wind tunnels, and surveying equipment in the field to plan contour banks; we also prepare 1:5 extracts, measure ECs, clay dispersion, and solution cations, then calculate SARs, cation concentrations and interpret the data in terms of their effects on soil structure; we run a nice practical to measure pH buffering capacity of soils and lime requirements, although students generally cringe over the calculations required.... In addition we use modern water content sensors, new equipment to measure saturated and unsaturated hydraulic conductivity, and instruments to measure soil water potential. 

Research Interests

Almost all the research I do is conducted collaboratively (it's the only way these days and it can also be lots of fun, particularly when students are involved). My main areas of interest include:

• Soil physics, especially soil water retention, movement and availability to plants.
• Soil structure, particularly in relation to the problem of aggregate coalescence in horticultural soils.
• Mechanisms of self-mulching behaviour in clays and clay soils.
• Influence of soil properties on mobility of colloids in the environment.

Here are some questions for potential research students to think about:

• How closely can we predict plant response to the soil physical environment? Our recent work in this area suggests there is plenty of room for improvement.

• To what extent do plants 'see' and respond to our best estimates of available water in soils? A recent student explored the way in which plants respond to declining unsaturated soil hydraulic conductivity in some light textured soils. Another student is currently evaluating how plant available water changes as soils are reclaimed from the saline-sodic state.

• What can we learn about the quality of structure and the mechanical properties in swelling soils from their shrinkage curves? Preliminary work suggests we can learn quite a lot from available data in the literature, but considerable experimental work is needed here to see just how far the ideas can be taken.

• Irrigated soils seem to become harder (they coalesce) during the growing season, to the point where root growth becomes restricted. This coalescence is observed as a large increase in strength with very little increase in bulk density (see recent publications: Grant et al. 2001). What conditions lead to this phenomenon and to what extent can it be managed? Preliminary work suggests that supply-water potential and drainage potential are critical particularly in soils of relatively low organic matter content.

• Plant roots have difficulty extracting water from the deeper layers of clay-textured soils. We have recently shown that overburden pressures (while not particularly large in the upper root zone) control water retention during shrinkage, and we think this severely restricts aeration at depth. There are virtually no data, however, showing the effects of overburden pressures on water potentials and soil volume, combined with soil strength and aeration during shrinkage. An opportunity exists here for a unique study that will have an impact on water-use efficiency on irrigated clay soils in Australia and internationally.

• When saline/sodic soils are leached, their salt contents decline, but clay dispersion becomes a problem until the cation status of the soils can be adjusted by addition of gypsum or other calcium source. The effects that clay swelling and dispersion have on available water in these soils is unknown.

• Why do some clay soils (and pure clays) form fine stable aggregates ("self-mulching") upon wetting and drying, whereas other clay soils that have apparently similar properties (i.e. plenty of 2:1 expanding lattice, Ca-saturated clay), do not do this. Preliminary work suggests this may be related to clay particle size and shape, but this has yet to be confirmed. A student interested in clays and clay minerals would find this an interesting project with many practical applications, including the properties of cricket pitches. If you like cricket, this could be a very fun project!

Publications

Selected Papers:  

• Field DJ, Koppi AJ, Jarret LE, Abbott LK, Cattle SR, Grant CD, McBratney AB, Menzies NW, Weatherley AJ 2011. Soil science teaching principles. Geoderma, 167-168, 9-14.
• Oliver IW, Grant CD, Murray RS 2011. Assessing effects of aerobic and anaerobic conditions on phosphorus sorption and retention capacity of water treatment residuals. Journal of Environmental Management, 92, 960-966.
• Grant CD, Groenevelt PH, Robinson NI 2010. Application of the Groenevelt-Grant soil water retention model to predict the hydraulic conductivity. Australian Journal of Soil Research, 48, 447-458.
• McBeath T, Grant CD, Murray RS, Chittleborough DJ 2010. Effects of subsoil amendments on soil physical properties, crop response and soil water quality in a dry year. Australian Journal of Soil Research, 48, 140-149.
• Groenevelt PH, Grant CD, Murray RS 2004. On water availability in saline soils. Australian Journal of Soil Research, 42, 833-840.
• Groenevelt PH, Grant CD 2004. Analysis of shrinkage data. Soil & Tillage Research, 79, 71-77.
• Groenevelt PH, Grant CD 2004. A new model for the soil-water retention curve that solves the problem of residual water contents. European Journal of Soil Science, 55, 479-485.
• Suriadi A, Murray RS, Grant CD, Nelson PN 2002. Structural stability of sodic soils in sugarcane production as influenced by gypsum and molasses. Australian Journal of Experimental Agriculture, 42, 315-322.
• Groenevelt PH, Grant CD 2002. Curvature of shrinkage lines in relation to the consistency and structure of a Norwegian clay soil. Geoderma, 106, 235-245.
• Groenevelt PH, Grant CD 2001. Re-evaluation of the structural properties of some British swelling soils. European Journal of Soil Science, 52, 469-477.
• Grant CD, Angers DA, Murray RS, Chantignay M, Hassanah U 2001. On the nature of soil aggregate coalescence in an irrigated swelling clay. Australian Journal of Soil Research, 39, 565-575.
• Groenevelt PH, Grant CD, Semetsa S 2001. A new procedure to determine soil water availability. Australian Journal of Soil Research, 39, 577-598.
• Noack AG, Grant CD, Chittleborough DJ 2000. Colloid movement through stable soils of low cation exchange capacity. Environmental Science & Technology, 34, 2490-2497.

Some Chapters in Books:  

• Grant CD 2008. 'Soil shrinkage' Chapter 56 in MR Carter and EG Gregorich (Eds) Soil Sampling and Methods of Analysis, 2nd edn. pp. 727-741. Canadian Society of Soil Science. CRC Press, Boca Raton, Florida.
• Grant CD, Groenevelt PH 2008. 'Air permeability' Chapter 60 in MR Carter and EG Gregorich (Eds) Soil Sampling and Methods of Analysis, 2nd edn. pp. 803-809. Canadian Society of Soil Science. CRC Press, Boca Raton, Florida.
• Grant CD, Groenevelt, PH, Bolt, GH 2002. On hydrostatics and matristatics of swelling soils. In PAC Raats, DE Smiles, A Warrick (Eds) 'Environmental mechanics: water, mass, and energy in the Biosphere'. American Geophysical Monograph Series, 129, 95-105.
• Grant CD, Coughlan KJ 2002 'Estimation of the self-mulching characteristics of surface soils' Chapter 29 in NJ McKenzie, KJ Coughlan, HP Cresswell (Eds). Soil Physical Measurement & Interpretation for Land Evaluation pp.370-2 Australian Soil & Land Survey Hdbk Series Vol.5. 320p. ISBN 0643067671 CSIRO.

Professional Associations

• Chairman, CPSS Accreditation Board, 2010-2011 (accredited at CPSS Stage 3).
• Editorial Board, Soil & Tillage Research, since 2004.
• President of ASSSI 2002-2004.
• Chairman, Program Committee, 19th World Congress of Soil Science, Brisbane 1-6 Aug 2010.
• Convener of 2006 ASSSI National Soils Conference, run jointly with the Australiasian Soil & Plant Analysis Council, and the Australian Clay Minerals Society
• Associate Editor, Canadian Journal of Soil Science, 2003-2006.
• Member, Australian Society of Soil Science Inc (ASSSI), since 1985.
• Member, International Soil Tillage Research Organisation (ISTRO) since 1988.
• Member, International Union of Soil Science (IUSS) since 1986.

Expertise for Media Contact

Categories	Environment
Expertise	Environment; soil physics; pollution; soil science (properties of water treatment sludges - especially phosphorus-sorption from polluted waters); soil science (soil physics, soil water management, plant available water); self-mulching clays; water quality and treatment
Notes	Alt phone: (08) 8303 7210

Entry last updated: Sunday, 5 Feb 2012