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Dr Gunnar Kirchhof

Senior Lecturer

School of Agriculture and Food Sustainability
Faculty of Science

Principal Research Fellow

School of Agriculture and Food Sustainability
Faculty of Science
g.kirchhof1@uq.edu.au
+61 7 336 51364

Overview

May 2002–ongoing: Senior Lecturer Land Resources Sciences, Principla Research Fellow, School of Land, Crop and Food Sciences; The University of Queensland, Australia

As lecturer of Land Resources Sciences at the University of Queensland, Dr Kirchhof has both led and collaborated on over half a dozen projects, and supervised numerous research staff and students. His research has focussed on:

  • Soil–Water relationships;
  • Conservation Agriculture and Irrigation scheduling
  • Soil erosion
  • Water and Nutrient Balances;
  • Spatial Variability of Soil Properties from Ped to Landscape Scales;
  • Dry-land Salinity Management;
  • Water Recycling
  • Computer Modelling of Water Flow with Special Reference to Variability and assessment of deep drainage
  • Knowledge Management;

2011-15 Course leader: Australia Awards in Africa Dryland Farming/Soil and Water conservation Short Course Awards, UniQuest; Australia and Africa, Dr Kirchhof led the design and delivery of the AusAID-funded Dryland Farming Short Course Award, contracted to UniQuest/UQ-ID through GRM International, which was delivered twice a year in 2011 and 2014.

Countries of work experience: Indonesia, Vietnam, Papua New Guinea, the Philippines, Burkino Faso, Côte d’Ivoire, Djibouti, Ethiopia, Nigeria, Tunisia, Uganda, Kenya, Tunisia, Australia.

Previous postions:

Oct 1997–May 2002: Senior Soil Scientist, Soil Conservation, NSW Agriculture; Australia

Mar 1996–Oct 1997: Soil Physicist, International Institute of Tropical Agriculture; Ibadan, Nigeria

Dec 1991–Mar 1996: Research Fellow, Department of Agriculture, The University of Queensland; Brisbane

Jan 1989–Dec 1991: Soil Scientist, CASSIRO Ltd, Wauchope, NSW

Research Interests

  • Soil and Water Management
    Water in the soil environment and landscapes: even though it is usually not considered a nutrient, it can in fact be seen as the most important nutrient. It drives productivity of our ago-ecosystems as well their sustainability. Water must be used efficiently, what can efficient water use achieve? What are the limits of this efficiency?
  • Conservation Agriculture
    Conservation Agriculture (CA) is considered the current best management practice for sustainable and productive ago-ecosystems. Is this correct? - May be not? We need to know more about practical suitability of CA in a range of environments, especially in Africa as wholesale promotion of CA can be detrimental to its adoption potential. The big questions are: is it a management method to satisfy world food demand? Can it be used to mitigate or manage climate change? What are its limitations?

Research Impacts

Conservation Agriculture – achieving impact in Africa

http://www.australiaawardsafrica.org/news/conservation-agriculture-achieving-impact-in-africa/

http://www.australiaawardsafrica.org/wp-content/uploads/2013/10/Conservation-Agriculture-Achieving-Impact-in-Africa.pdf

Qualifications

  • Graduate Certificate in Education, The University of Queensland
  • Doctor of Philosophy, The University of Queensland
  • Graduate Dipl Agricultural Studies, Gottfried Wilhelm Leibniz Universität Hannover

Publications

View all Publications

Grants

View all Grants

Supervision

View all Supervision

Available Projects

  • Runoff and erosion from very dry clay soil surfaces: does conventional infiltration theory apply?

    Accepted conventional infiltration theory states that application of water to dry soil over time follows two phases: first, the sorptive phase where capillarity rapidly fills the pore system, and the steady state phase where the pore system conducts water at the rate of the soil saturated hydraulic conductivity. In most cases, this is also what we observe in the field: water enters the soil quickly and it then slows down to reach a steady rate. This infiltration theory assumes that the wetting angle of the capillaries is 0°; i.e. the capillary has a water film. If the wetting angle is larger than 0°, the capillary potential that drives water intake during the sorptive phase will also be much smaller, resulting in slow sorptivity. On hydrophobic soils, the wetting angle can approach 90° or, in extreme cases become convex.

    Applying water to very dry soil, perhaps after a long drought, or soil surfaces that were exposed to bushfires or soils with water repellent organic matter, may not have a capillary water film that allows immediate rapid water intake. Under field conditions this can occasionally be observed when water is applied to very dry soil: it initially ponds on the surface before it then quickly infiltrates. This initial ponding may be the consequence of a larger than 0° wetting angle. The length of initial ponding will affect the onset of runoff and erosion. Although the problem of hydrophobicity is a well-known problem on sandy soils, water repellence on clay soils has been observed but is not well understood.

    This project aims to verify if the sorptive phase can be preceded by a ponded phase and under what conditions it can occur. The experimental plan would assess the impact of soil type and texture, soil organic matter, and antecedent soil water content on the formation of an initial potential ponded phase. The research would initially be conducted under laboratory conditions using intact soil cores (St Lucia or Gatton Research Labs) and possibly followed up for in situ field conditions.

    The results will have implications on how to prepare and avoid runoff and erosion from very dry soils during a heavy rainfall event.

  • Quantifying the interaction between soil organic matter, nitrogen fertiliser and hydraulic conductivity on the Hermitage Long term Trials

    The Hermitage Long Term trial has been running since 1968. The trial assessed a range of agronomic and soil science responses to conservation agriculture type practices and fertilisation regimes. Much data has been collected over the years with the most recent being submitted for publication by Kuntal Hatia et al. late 2020. This paper provides excellent data for soil aggregation as a consequence of tillage methods, stubble retention, and nitrogen fertilisation. Another important dataset is the impact of these management parameters on saturated hydraulic conductivity and the van Genuchten hydraulic conductivity model. This project aims to measure in situ saturated hydraulic conductivity using rainfall simulation and nitrometers as well as collecting undisturbed cores for Ksat and pF-curve determination to parameterise the van Genuchten model. The aim is to publish a follow-up paper with Kuntal Hatia et al.

  • Can ground cover-induced concentrated flow increase soil erosion?

    Maintaining adequate ground cover is the ‘golden’ rule to reduce soil erosion. Leaf litter or similar absorbs the kinetic energy of rain drops as they hit the soil surface. This reduces soil surface disturbance and prevents aggregate breakdown that can lead to the formation of a surface seal. Under some conditions, however, in particular on steep slopes, adequate ground cover may not protect the soil from erosion even if the soil hydraulic conductivity exceeds rainfall intensity. The mechanism that can lead to runoff and then erosion may be due to the formation of concentrated flow.

    Consider a thought experiment: our soil surface has a saturated hydraulic conductivity of 30 mm/h and we have a rainfall intensity of 20 mm/h: we should not get runoff! Now 50% of the soil is covered and hence, only 50% of the soil surface can take in water. This means that the hydraulic conductivity of the uncovered soil must be at least 40 mm/h to prevent runoff (i.e. 20 mm/h from the rainfall plus 20 mm/h that enters the soil as runoff from the groundcover). Therefore we would have runoff as the hydraulic conductivity is only 30 mm/h. Of course, this thought experiment does not apply to the real world, but the principle is still valid.

    This project aims to assess the impact of groundcover on the formation of concentrated flow. The experimental plan would assess the effect of soil hydraulic conductivity, slope, and ground cover type and quantity on runoff and erosion. The project will be conducted at the Erosion Processes Laboratory at the St Lucia campus and can be supplemented in-situ using our field rainfall simulator and infiltrometer equipment.

    The results will have implications on recommended management practices of sloping soil to prevent soil erosion.

View all Available Projects

Publications

Book

Book Chapter

  • Puddling: effect on soil physical properties and crops

    Kirchhof, Gunnar, Tuong, T. P. and So, H. B. (2011). Puddling: effect on soil physical properties and crops. Encyclopedia of agrophysics. (pp. 667-668) edited by Jan Gliński, Józef, Horabik and Jerzy Lipiec. Dordrecht, Netherlands: Springer. doi: 10.1007/978-90-481-3585-1_129

  • An analysis of village garden management in the Papua New Guinea highlands

    Wegener, M., Kirchhof, G. and Wilson, T. (2009). An analysis of village garden management in the Papua New Guinea highlands. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 88-94) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Biophysical constraints of sweetpotato-based cropping systems in the Papua New Guinea highlands

    Kirchhof, Gunnar, Taraken, Issac T., Ramakrishna, Akkinapally, Ratsch, Rainer and Igua, Passinghan (2009). Biophysical constraints of sweetpotato-based cropping systems in the Papua New Guinea highlands. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 95-109) edited by Gunnar Kirchhof. Canberra, A.C.T., Australia: Australian Centre for International Agricultural Research.

  • Changing tillage management practices and their impact on soil structural properties in north-western New South Wales, Australia

    Kirchhof, Gunnar and Daniells, Ian (2009). Changing tillage management practices and their impact on soil structural properties in north-western New South Wales, Australia. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 60-69) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Overview of soil conservation technologies and their perception by farmers in Nigeria

    Junge, B., Deji, O., Abaidoo, R., Chikoye, D. and Kirchhof, G. (2009). Overview of soil conservation technologies and their perception by farmers in Nigeria. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 49-59) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Soil management in the northern Guinea savanna of Nigeria

    Kirchhof, G., Odunze, A. C. and Salako, F. K. (2009). Soil management in the northern Guinea savanna of Nigeria. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 43-48) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Statistical methods for a soil fertility management survey analysis in Papua New Guinea

    Kravchuk, O., Wilson, T. and Kirchhof, G. (2009). Statistical methods for a soil fertility management survey analysis in Papua New Guinea. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 79-87) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Survey methodology to assess socioeconomic and biophysical constraints—lessons learnt in the highlands of Papua New Guinea

    Kirchhof, G., Taraken, I.T., Ratsch, R., Kapal, D. and Igua, P. (2009). Survey methodology to assess socioeconomic and biophysical constraints—lessons learnt in the highlands of Papua New Guinea. Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. (pp. 70-78) edited by Gunnar Kirchhof. Canberra, ACT, Australia: Australian Centre for International Agricultural Research.

  • Plastic properties

    Kirchhof, Gunnar (2007). Plastic properties. Encyclopedia of soil science. edited by Rattan Lal. New York, United States: Taylor & Francis. doi: 10.1081/E-ESS-120001587

Journal Article

Conference Publication

Edited Outputs

  • Leucaena as an opportunity for recharge management in northern Australia: Fitzroy Basin case study

    Shelton, H. M., Kirchhof, G., Emmery, P., Sheehan, W., Rowlings, D., Poole, H. and Budisantoso, E. eds. (2003). Leucaena as an opportunity for recharge management in northern Australia: Fitzroy Basin case study. 9th National Productive Use and Rehabilitation of Saline Lands (PUR$L), Rydges Capricorn Resort, Yeppoon, 29 September - 2 October, 2003. Yeppoon, Queensland: PUR$L.

  • Soil & Tillage Research

    Soil & Tillage Research. (2000). 56 (1-2)

  • Management of clay soils for rainfed lowland rice-based cropping systems

    Kirchhof, G. and So, H. B. eds. (1996). Management of clay soils for rainfed lowland rice-based cropping systems. Proceedings of ACIAR International Workshop held at the Bureau of Soil and Water Management, Quezon City, Manila, Philippines, 20-24 November 1995 . Canberra, ACT, Australia : Australian Centre for International Agricultural Research.

Other Outputs

Grants (Administered at UQ)

PhD and MPhil Supervision

Current Supervision

  • An investigation into the chemical, physical and biological properties of manufactured soil produced from bauxite residue

    Doctor Philosophy — Associate Advisor

    Other advisors:

Completed Supervision

Possible Research Projects

Note for students: The possible research projects listed on this page may not be comprehensive or up to date. Always feel free to contact the staff for more information, and also with your own research ideas.

  • Runoff and erosion from very dry clay soil surfaces: does conventional infiltration theory apply?

    Accepted conventional infiltration theory states that application of water to dry soil over time follows two phases: first, the sorptive phase where capillarity rapidly fills the pore system, and the steady state phase where the pore system conducts water at the rate of the soil saturated hydraulic conductivity. In most cases, this is also what we observe in the field: water enters the soil quickly and it then slows down to reach a steady rate. This infiltration theory assumes that the wetting angle of the capillaries is 0°; i.e. the capillary has a water film. If the wetting angle is larger than 0°, the capillary potential that drives water intake during the sorptive phase will also be much smaller, resulting in slow sorptivity. On hydrophobic soils, the wetting angle can approach 90° or, in extreme cases become convex.

    Applying water to very dry soil, perhaps after a long drought, or soil surfaces that were exposed to bushfires or soils with water repellent organic matter, may not have a capillary water film that allows immediate rapid water intake. Under field conditions this can occasionally be observed when water is applied to very dry soil: it initially ponds on the surface before it then quickly infiltrates. This initial ponding may be the consequence of a larger than 0° wetting angle. The length of initial ponding will affect the onset of runoff and erosion. Although the problem of hydrophobicity is a well-known problem on sandy soils, water repellence on clay soils has been observed but is not well understood.

    This project aims to verify if the sorptive phase can be preceded by a ponded phase and under what conditions it can occur. The experimental plan would assess the impact of soil type and texture, soil organic matter, and antecedent soil water content on the formation of an initial potential ponded phase. The research would initially be conducted under laboratory conditions using intact soil cores (St Lucia or Gatton Research Labs) and possibly followed up for in situ field conditions.

    The results will have implications on how to prepare and avoid runoff and erosion from very dry soils during a heavy rainfall event.

  • Quantifying the interaction between soil organic matter, nitrogen fertiliser and hydraulic conductivity on the Hermitage Long term Trials

    The Hermitage Long Term trial has been running since 1968. The trial assessed a range of agronomic and soil science responses to conservation agriculture type practices and fertilisation regimes. Much data has been collected over the years with the most recent being submitted for publication by Kuntal Hatia et al. late 2020. This paper provides excellent data for soil aggregation as a consequence of tillage methods, stubble retention, and nitrogen fertilisation. Another important dataset is the impact of these management parameters on saturated hydraulic conductivity and the van Genuchten hydraulic conductivity model. This project aims to measure in situ saturated hydraulic conductivity using rainfall simulation and nitrometers as well as collecting undisturbed cores for Ksat and pF-curve determination to parameterise the van Genuchten model. The aim is to publish a follow-up paper with Kuntal Hatia et al.

  • Can ground cover-induced concentrated flow increase soil erosion?

    Maintaining adequate ground cover is the ‘golden’ rule to reduce soil erosion. Leaf litter or similar absorbs the kinetic energy of rain drops as they hit the soil surface. This reduces soil surface disturbance and prevents aggregate breakdown that can lead to the formation of a surface seal. Under some conditions, however, in particular on steep slopes, adequate ground cover may not protect the soil from erosion even if the soil hydraulic conductivity exceeds rainfall intensity. The mechanism that can lead to runoff and then erosion may be due to the formation of concentrated flow.

    Consider a thought experiment: our soil surface has a saturated hydraulic conductivity of 30 mm/h and we have a rainfall intensity of 20 mm/h: we should not get runoff! Now 50% of the soil is covered and hence, only 50% of the soil surface can take in water. This means that the hydraulic conductivity of the uncovered soil must be at least 40 mm/h to prevent runoff (i.e. 20 mm/h from the rainfall plus 20 mm/h that enters the soil as runoff from the groundcover). Therefore we would have runoff as the hydraulic conductivity is only 30 mm/h. Of course, this thought experiment does not apply to the real world, but the principle is still valid.

    This project aims to assess the impact of groundcover on the formation of concentrated flow. The experimental plan would assess the effect of soil hydraulic conductivity, slope, and ground cover type and quantity on runoff and erosion. The project will be conducted at the Erosion Processes Laboratory at the St Lucia campus and can be supplemented in-situ using our field rainfall simulator and infiltrometer equipment.

    The results will have implications on recommended management practices of sloping soil to prevent soil erosion.

  • Reducing wind erodibility through increasing aggregate stability through mulch management

    The soil property that primarily drives susceptibility to wind erosion is aggregate size distribution. On soils that are susceptible to wind erosion, management practices to reduce wind erosion aim to increase aggregate sizes. This can be achieved by mulch application that leads to an increase in soil organic matter and re-aggregation of soil structure during wetting and drying cycles. How effective mulch application will be is likely to be dependent on the quantity and type or mulch applied. This project aims to assess aggregate size distribution as measured by dry sieving in response to wet-dry cycles and mulch type and quantity. The experiment will be carried out either at Gatton or St Lucia. It will run over two semesters to ensure sufficient breakdown of applied mulch under a number of wet-dry cycles

  • Micro-topography of soil surfaces and its effect on erosion

    Soil erodibility by water is strongly affected soil surface roughness. The description of surface roughness in relation to erosion is surface water storage capacity which is the volume of water that is can be held in the surface depressions before the overflow, and the surface roughness per se that is commonly expressed as the Manning coefficient. Three-dimensional mapping of the soil surface is an alternative, though not very well researched alternative, to assess erodibility of soil surfaces. Close-range photogrammetry can potentially be used to generate high-resolution digital elevation models to assess the flow of water and subsequent erosion from bare soil surfaces. This project will investigate if photogrammetry can be used to identify surface properties that can be used to assess surface susceptibility to soil erosion.

  • Can laser refraction be used to assess soil structural stability?

    Soil science has a myriad of methods to measure soil structural stability. Conventional methods range from, for example, wet and dry sieving, soil strength, various types of dispersion tests, and more engineering-type tests. Most of these tests apply energy to break up soil structure and then use crisp empirical data sets to assess the change in aggregation as a consequence of energy input. Sieving methods are limited by how many sieves are used and the crisp set always results in a very limited number of aggregate size fractions; the crisp data set of dispersion is almost binary data. The same applies to particle size distribution where particle distribution is simplified to a small number of size classes. In most cases only the three main classes; i.e. sand silt and clay. A relatively new method to measure a continuous particle size distribution by laser refraction. This method can potentially also be used to measure the stability of aggregate size distribution rather than a limited number of size classes by sieving to different mesh sizes. Only limited data exist where laser refraction has been used to assess soil structural stability.

    The first part of this project aims to develop a robust methodology to assess aggregate size distribution stability using laser refraction, the 2nd part of the project is to assess the method’s ability to quantify aggregate size distribution stability on Ferrosols with different organic carbon contents. The project will use the laser refraction machine Malvern Mastersizer 2000 located at the St Lucia soil laboratories.

This staff member is a UQ Expert for media in the following fields:

Soil science, Soil management, Papua New Guinea - highland soil, Urban water recycling, Agro-ecosystems - tropical, Tropical and temperate regions - soil, Water recycling, Papua New Guinea - farming, Water utilities, Soil - fertility decline, Water management, Conservation agriculture

They are happy to lend their expertise to your articles or broadcasts and share their research discoveries and insights with the community via media channels.

For additional assistance with story ideas, general advice and information or help with seeking further experts, please email the UQ Media Team or telephone (07) 3365 1120.

Links

ResearcherID: I-9146-2012

ORCID: 0000-0002-9480-6579

Google Scholar ID: hrYIYy4AAAAJ

Personal Profile: Link

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