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:
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
Conservation Agriculture – achieving impact in Africa
http://www.australiaawardsafrica.org/news/conservation-agriculture-achieving-impact-in-africa/
Other Outputs: Strengthening capacities to innovate through North-South collaborative agricultural research in Papua New Guinea
Kirchhof, Gunnar (2022). Strengthening capacities to innovate through North-South collaborative agricultural research in Papua New Guinea. Asia-Pacific Islands Rural Advisory Services Network (APIRAS) Hyderabad Telangana, India: Food and Agriculture Organization of the United Nations.
Journal Article: Responses of soil organic carbon, aggregate diameters, and hydraulic properties to long-term organic and conventional farming on a Vertisol in India
Schweizer, Steffen A., Graf-Rosenfellner, Markus, Bhat, Nisar A., Kayser, Gilles, Sisodia, Bhupendra S., Kirchhof, Gunnar, Zikeli, Sabine, Cadisch, Georg and Bhullar, Gurbir S. (2022). Responses of soil organic carbon, aggregate diameters, and hydraulic properties to long-term organic and conventional farming on a Vertisol in India. Land Degradation and Development, 33 (5), 785-797. doi: 10.1002/ldr.4216
Journal Article: 50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol
Hati, Kuntal M., Jha, Pramod, Dalal, Ram C., Jayaraman, Somasundaram, Dang, Yash P., Kopittke, Peter M., Kirchhof, Gunnar and Menzies, Neal W. (2021). 50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol. Soil and Tillage Research, 214 105163, 1-11. doi: 10.1016/j.still.2021.105163
(2023–2026) GRDC - PROC-9176764 - Understanding crop development and yield responses to mitigate high soil strength in Australian soils.
(2022–2024) Future Drought Fund: Drought Resilient Soils and Landscapes Grants
Sustaining soil fertility in support of intensification of sweetpotato cropping systems
(2016–2024) Australian Centre for International Agricultural Research
Nitrogen and root zone temperature effects on sweetpotato cultivation on large mounds
(2018) Doctor Philosophy
Improving the capacity to represent surface runoff processes in rangeland biophysical models
(2014) Doctor Philosophy
An investigation into the chemical, physical and biological properties of manufactured soil produced from bauxite residue
Doctor Philosophy
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.
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.
Menzies, Neal , Page, Kathryn , Dalal, Ram , Dang, Yash , Kopittke, Peter , Wehr, Bernhard , Orton, Thomas , Kirchhof, G. and Fujinuma, R. (2017). Technical Management of soil physical and chemical constraints to grains cropping in Queensland and New South Wales: A review. Technical Final report (UQ00084). Canberra, ACT, Australia: GRDC.
Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea
Gunnar Kirchhof ed. (2009). Soil fertility in sweetpotato-based cropping systems in the highlands of Papua New Guinea. ACIAR technical reports, Canberra, ACT, Australia: Australian Centre for International Agricultural Research.
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.
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.
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.
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
Schweizer, Steffen A., Graf-Rosenfellner, Markus, Bhat, Nisar A., Kayser, Gilles, Sisodia, Bhupendra S., Kirchhof, Gunnar, Zikeli, Sabine, Cadisch, Georg and Bhullar, Gurbir S. (2022). Responses of soil organic carbon, aggregate diameters, and hydraulic properties to long-term organic and conventional farming on a Vertisol in India. Land Degradation and Development, 33 (5), 785-797. doi: 10.1002/ldr.4216
Hati, Kuntal M., Jha, Pramod, Dalal, Ram C., Jayaraman, Somasundaram, Dang, Yash P., Kopittke, Peter M., Kirchhof, Gunnar and Menzies, Neal W. (2021). 50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol. Soil and Tillage Research, 214 105163, 1-11. doi: 10.1016/j.still.2021.105163
Gamma irradiation with 50 kGy has a limited effect on agronomic properties of air-dry soil
Wehr, J. Bernhard and Kirchhof, Gunnar (2021). Gamma irradiation with 50 kGy has a limited effect on agronomic properties of air-dry soil. Soil Systems, 5 (2) 28, 28. doi: 10.3390/soilsystems5020028
Page, K. L., Dalal, R. C., Wehr, J. B., Dang, Y. P., Kopittke, P. M., Kirchhof, G., Fujinuma, R. and Menzies, N. W. (2018). Management of the major chemical soil constraints affecting yields in the grain growing region of Queensland and New South Wales, Australia – a review. Soil Research, 56 (8), 765-779. doi: 10.1071/sr18233
Root zone temperature alters storage root formation and growth of sweetpotato
Taranet, P., Kirchhof, G., Fujinuma, R. and Menzies, N. (2018). Root zone temperature alters storage root formation and growth of sweetpotato. Journal of Agronomy and Crop Science, 204 (3), 313-324. doi: 10.1111/jac.12262
Fujinuma, Ryosuke, Kirchhof, Gunnar, Ramakrishna, Akkinapally, Sirabis, William, Yapo, Jeffery, Woruba, Deane, Gurr, Geoff and Menzies, Neal (2018). Intensified sweetpotato production in Papua New Guinea drives plant nutrient decline over the last decade. Agriculture, Ecosystems & Environment, 254, 10-19. doi: 10.1016/j.agee.2017.11.012
The effect of salinity on plant-available water
Sheldon, Anna R., Dalal, Ram C., Kirchhof, Gunnar, Kopittke, Peter M. and Menzies, Neal W. (2017). The effect of salinity on plant-available water. Plant and Soil, 418 (1-2), 477-491. doi: 10.1007/s11104-017-3309-7
Growth and yield response of glasshouse- and field-grown sweetpotato to nitrogen supply
Taranet, Prapa, Harper, Stephen, Kirchhof, Gunnar, Fujinuma, Ryosuke and Menzies, Neal (2017). Growth and yield response of glasshouse- and field-grown sweetpotato to nitrogen supply. Nutrient Cycling in Agroecosystems, 108 (3), 309-321. doi: 10.1007/s10705-017-9858-6
Gurr, G.M., Johnson, A.C., Waruba, D.N., Kirchhof, G., Fujinuma, R., Sirabis, W., Jeffery, Y. and Akkinapally, R. (2016). Pests, diseases and crop protection practices in the smallholder sweetpotato production system of the highlands of Papua New Guinea. PeerJ, 4 (12) e2703, e2703. doi: 10.7717/peerj.2703
Gurr, Geoff M., Liu, Jian, Johnson, Anne C., Woruba, Deane N., Kirchhof, Gunnar, Fujinuma, Ryosuke, Sirabis, William, Jeffery, Yapo and Akkinapally, Ramakrishna (2016). Pests, diseases and crop protection practices in the smallholder sweetpotato production system of the highlands of Papua New Guinea. PeerJ, 4 (12) e2703. doi: 10.7287/peerj.preprints.2394
Early response of soil properties and function to riparian rainforest restoration
Gageler, Rose, Bonner, Mark, Kirchhof, Gunnar, Amos, Mark, Robinson, Nicole, Schmidt, Susanne and Shoo, Luke P. (2014). Early response of soil properties and function to riparian rainforest restoration. PLoS One, 9 (8) e104198, e104198.1-e104198.8. doi: 10.1371/journal.pone.0104198
Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland
Radrizzani, Alejandro, Shelton, H. Max, Dalzell, Scott A. and Kirchhof, Gunnar (2011). Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland. Crop and Pasture Science, 62 (4), 337-345. doi: 10.1071/CP10115
In vitro starch digestion and potassium release in sweet potato from Papua New Guinea dagger
Liu, Yun, Sabboh, Houda, Kirchhof, Gunnar and Sopade, Peter (2010). In vitro starch digestion and potassium release in sweet potato from Papua New Guinea dagger. International Journal of Food Science and Technology, 45 (9), 1925-1931. doi: 10.1111/j.1365-2621.2010.02356.x
Sensitivity of drainage to rainfall, vegetation and soil characteristics
Bah, A.R., Kravchuk, O. and Kirchhof, G. (2009). Sensitivity of drainage to rainfall, vegetation and soil characteristics. Computers And Electronics In Agriculture, 68 (1), 1-8. doi: 10.1016/j.compag.2009.03.005
Bah, A.R., Kravchuk, O. and Kirchhof, G. (2009). Fitting performance of particle-size distribution models on data derived by conventional and laser diffraction techniques. Soil Science Society of America Journal, 73 (4), 1101-1107. doi: 10.2136/sssaj2007.0433
Ramakrishna, A., Bailey, J. S. and Kirchhof, G. (2009). A preliminary diagnosis and recommendation integrated system (DRIS) model for diagnosing the nutrient status of sweet potato (Ipomea batatas). Plant and Soil, 316 (1-2), 107-116. doi: 10.1007/s11104-008-9763-5
Bailey, J. S., Ramakrishna, A. and Kirchhof, G. (2009). An evaluation of nutritional constraints on sweet potato (Ipomoea batatas) production in the central highlands of Papua New Guinea. Plant and soil, 316 (1-2), 97-105. doi: 10.1007/s11104-008-9762-6
Influence of hydraulic loading and effluent flux on surface surcharging in soil absorption systems
Beal, C.D., Rassam, D.W., Gardner, E.A., Kirchhof, G. and Menzies, N. W. (2008). Influence of hydraulic loading and effluent flux on surface surcharging in soil absorption systems. Journal of Hydrologic Engineering, 13 (8), 681-692. doi: 10.1061/(ASCE)1084-0699(2008)13:8(681)
Bailey, J.S., Ramakrishna, A. and Kirchhof, G. (2008). Relationships between important soil variables in moderately acidic soils (ph>5.5)in the highlands of Papua New Guinea and management implications for subsistence farmers. Soil Use And Management, 24 (3), 281-291. doi: 10.1111/j.1475-2743.2008.00161.x
Kirchhof, G., Ramakrishna, K. and Bailey, J.S. (2008). An evaluation of Colwell-P as a measure of plant-available phosphorus in soils of volcanic and non-volcanic origins in the highlands of Papua New Guinea. Soil Use And Management, 24 (4), 331-336. doi: 10.1111/j.1475-2743.2008.00160.x
Salako, E. K., Olowokere, E. A., Tian, G., Kirchhof, G. and Osiname, O. (2007). Ground cover by three crops cultivated on marginal lands in southwestern Nigeria and implications for soil erosion. Spanish Journal of Agricultural Research, 5 (4), 497-505. doi: 10.5424/sjar/2007054-272
Long-term flow rates and biomat zone hydrology in soil columns receiving septic tank effluent
Beal, CD, Gardner, EA, Kirchhof, G and Menzies, NW (2006). Long-term flow rates and biomat zone hydrology in soil columns receiving septic tank effluent. Water Research, 40 (12), 2327-2338. doi: 10.1016/j.watres.2006.04.018
Salako, F. K., Kirchhof, G. and Tian, G. (2006). Management of a previously eroded tropical Alfisol with herbaceous legumes: Soil loss and physical properties under mound tillage. Soil & Tillage Research, 89 (2), 185-195. doi: 10.1016/j.still.2005.07.010
Salako, K., Tian,, Kirchhof, G. and Akinbola, G.E. (2006). Soil particles in agricultural landscapes of a derived savanna in southwestern Nigeria and implications for selectedsoil properties. Geoderma, 137 (1-2), 90-99. doi: 10.1016/j.geoderma.2006.06.017
NAIAD: sharing lessons from innovative urban water schemes
Loetscher, T., Dart, P. J., Kirchhof, G. and Gray, S. (2005). NAIAD: sharing lessons from innovative urban water schemes. Water, 32 (6), 60-62.
Kirchhof, G. and So, H. B. (2005). Rice growth and post-rice mungbean in relation to two puddling intensities under glasshouse conditions. Australian Journal of Soil Research, 43 (5), 623-628. doi: 10.1071/SR04067
Kirchhof, G. and So, H. B. (2005). Soil puddling for rice production under glasshouse conditions—its quantification and effect on soil physical properties. Australian Journal of Soil Research, 43 (5), 617-622. doi: 10.1071/SR04068
Field hydraulic properties of an Alfisol under various fallow systems in southwestern Nigeria
Salako, F.K. and Kirchhof, G. (2003). Field hydraulic properties of an Alfisol under various fallow systems in southwestern Nigeria. Soil Use And Management, 19 (4), 340-346. doi: 10.1111/j.1475-2743.2003.tb00324.x
A technique to assess small-scale heterogeneity of chemical properties in soil aggregates
Kirchhof, G. and Daniel, H. (2003). A technique to assess small-scale heterogeneity of chemical properties in soil aggregates. Australian Journal of Soil Research, 41 (5), 919-932. doi: 10.1071/SR02125
Crop establishment of legumes in rainfed lowland rice-based cropping systems
Rahmianna, AA, Adisarwanto, T, Kirchhof, G and So, HB (2000). Crop establishment of legumes in rainfed lowland rice-based cropping systems. Soil and Tillage Research, 56 (1-2), 67-82. doi: 10.1016/S0167-1987(00)00123-9
Kirchhof, G., So, H. B., Adisarwanto, T., Utomo, W. H., Priyono, S., Prastowo, B., Basir, M., Lando, T. M., Subandi, Dacanay, E. V., Tan-Elicano, D. and Sanidad, W. B. (2000). Growth and yield response of grain legumes to different soil management practices after rainfed lowland rice. Soil and Tillage Research, 56 (1-2), 51-66. doi: 10.1016/S0167-1987(00)00122-7
Management of clay soils for rainfed lowland rice-based cropping system
So, B. H. B. and Kirchhof, G. (2000). Management of clay soils for rainfed lowland rice-based cropping system. Soil and Tillage Research, 56 (1-2), 1-2. doi: 10.1016/S0167-1987(00)00118-5
Kirchhof, G., Priyono, S., Utomo, W. H., Adisarwanto, T., Dacanay, E. and So, B. H. B. (2000). The effect of soil puddling on the soil, physical properties and the growth of rice and post-rice crops. Soil and Tillage Research, 56 (1-2), 37-50. doi: 10.1016/S0167-1987(00)00121-5
Schafer, B. and Kirchhof, G. (2000). The soil and climate characterisation of benchmark sites for lowland rice-based cropping systems research in the Phillippines and Indonesia. Soil and Tillage Research, 56 (1-2), 15-35. doi: 10.1016/S0167-1987(00)00120-3
Jayawardane, N. S., Barrs, H. D., Muirhead, W. A., Blackwell, J., Murray, E. and Kirchhof, G. (1995). Lime-Slotting Technique To Ameliorate Subsoil Acidity In A Clay Soil. II. Effects On Medic Root Growth, Water Extraction And Yield. Australian Journal of Soil Research, 33 (3), 443-459. doi: 10.1071/SR9950443
Kirchhof, G., Jayawardane, N. S., Blackwell, J. and Murray, E. (1995). Lime-slotting technique to ameliorate subsoil acidity in a clay soil. I. effects on soil ph and physical characteristics. Australian Journal of Soil Research, 33 (3), 425-441. doi: 10.1071/SR9950425
Jeffrey, Yapo, Sirabis, William, Atung, Cyril, Ramakrishna, Akkinapally, Wehr, Bernhard, Menzies, Neal and Kirchhof, Gunnar (2021). Soil fertility management techniques for increased sweetpotato root yield in Papua New Guinea (PNG) highlands. The Soil Science Australia and the New Zealand Society of Soil Science Joint Conference, Cairns, QLD Australia, 27 June - 2 July 2021.
Yeffrey, Yapo, Sirabis, William, Wehr, Bernhard, Menzies, Neal and Kirchhof, Gunnar (2021). Sweetpotato yield comparison from pathogen tested and non-pathogen tested vines with coffee pulp in the PNG Highlands. The Soil Science Australia and the New Zealand Society of Soil Science Joint Conference., Cairns, QLD Australia, 27 June - 2 July 2021.
Assessment of soil structural properties in relation to land use change in South-East Asia
Lastic, Rachel de, Hoàng, Thảo, Nguyen, Phuong, Son, Sovanda, Suos, Vuthy and Kirchhof, Gunnar (2020). Assessment of soil structural properties in relation to land use change in South-East Asia. The Third International Tropical Agriculture Conference TropAg 2019 , Brisbane, QLD Australia, 11–13 November 2019. Basel, Switzerland: MDPI. doi: 10.3390/proceedings2019036182
Ogunwole, Joshua, Kirchhof, Gunnar, Birhanu, Birhanu Z., Duiker, Sjoerd and Pires, Luiz F. (2020). Jatropha curcas development as intervention potential to tackling land, energy and food challenges of rural communities in dryland sub-Saharan Africa. Third International Tropical Agriculture Conference (TROPAG 2019), Brisbane, Australia, 11-13 November 2019. Basel, Switzerland: MDPI . doi: 10.3390/proceedings2019036085
Digestibility of starch and potassium in sweetpotato from Papua New Guinea
Liu, Y., Sabboh, H., Kirchhof, G. and Sopade, P. A. (2009). Digestibility of starch and potassium in sweetpotato from Papua New Guinea. 15th Triennial Symposium of the International Society for Tropical Root Crops, Lima, Peru, 2-6 November 2009. Peru: International Society for Tropical Root Crops.
Soil fertility assessment of soils in the highlands of Papua New Guinea
Kirchhof, G. and Ramakrishna A. (2008). Soil fertility assessment of soils in the highlands of Papua New Guinea. Soils2008 Conference – Soil, the living skin of planet Earth, Palmerston North, New Zealand, 1-5 December 2008. New Zealand: AGMARDT.
Impact of saturated hydraulic conductivity and rainfall on variability of predicted drainage
Bah, Abdul R., Kravchuk, Olena and Kirchhof, Gunnar (2006). Impact of saturated hydraulic conductivity and rainfall on variability of predicted drainage. ASSSI – ASPAC – ACMS National Soils Conference - Soil Science Solving Problems, Adelaide, Australia, 3-7 December 2006. Australia: ASSSI-ASPAC-ACMS.
Naiad: Sharing lessons learned from innovative urban water schemes
Loetscher, T., Gray, S., Kirchhof, G. and Dart, P. (2005). Naiad: Sharing lessons learned from innovative urban water schemes. Ozwater Conference 2005, Brisbane, 8-12 May 2005. [Willoughby, N.S.W]: Australian Water Association.
Nitrogen cycling and grass sustainability in leucana-grass pastures - a research proposal
Radrizzani, A., Shelton, H. M., Kirchof, G. and Dalzell, S. A. (2005). Nitrogen cycling and grass sustainability in leucana-grass pastures - a research proposal. Australian Society of Animal Production, Central Queensland Sub-Branch Mini-conference, Rockhampton, Qld Australia, 5-6 July, 2005.
Soil management practices in northern New South Wales
Kirchhof, G. and Daniells, I. (2003). Soil management practices in northern New South Wales. International Soil Tillage Research Organisation 16th Triennial Conference, The University of Queensland, 13-18 July, 2003. Brisbane: The University of Queensland.
Structural regeneration of puddled soil
Bakti, L.A.A., So, B. H. B., Kirchhof, G. and Yatapanage, K. G. (2003). Structural regeneration of puddled soil. International Soil Tillage Research Organisation 16th Triennial Conference, The University of Queensland, 13-18 July, 2003. Brisbane: The University of Queensland.
Danesh, M., Daniel, H. and Kirchhof, G. (2002). The impact of long-term crop rotations and residue management on physical properties of a northern NSW Black earth (Vertosol). Australian Society of Soil Science National Conference, Perth, Western Australia, 2-6 December, 2002. Perth, Western Australia: The Australian Society of Soil Science Inc..
Variability of deep drainage: paddock leakiness hot spots
Kirchhof, G., Johnson, I. and Daniel, H. (2002). Variability of deep drainage: paddock leakiness hot spots. Australian Society of Soil Science National Conference, Perth, Western Australia, 2-6 December, 2002. Perth, Western Australia: The Australian Society of Soil Science Inc.
Low input tillage/cropping systems for limited resource areas
So, H. B., Kirchhof, G., Bakker, R. and Smith, G. D. (2001). Low input tillage/cropping systems for limited resource areas. 15th Conference of the International Soil Tillage Research Organization, Texas, United States of America, 02-07 July 2000 JUL 02-07, 2000. Amsterdam, Netherlands: Elsevier. doi: 10.1016/S0167-1987(01)00182-9
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. (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.
Kirchhof, Gunnar (2022). Strengthening capacities to innovate through North-South collaborative agricultural research in Papua New Guinea. Asia-Pacific Islands Rural Advisory Services Network (APIRAS) Hyderabad Telangana, India: Food and Agriculture Organization of the United Nations.
Sustaining soil fertility in support of intensification of Sweetpotato cropping systems
Wehr, Bernhard, Kirchhof, Gunnar and Menzies, Neal (2020). Sustaining soil fertility in support of intensification of Sweetpotato cropping systems. Canberra, ACT, Australia: ACIAR.
Sustaining soil fertility in support of intensification of Sweetpotato cropping systems
Wehr, Bernhard, Kirchhoff, Gunnar and Menzies, Neal (2019). Sustaining soil fertility in support of intensification of Sweetpotato cropping systems. Canberra, ACT, Australia: ACIAR.
Compaction properties of vertisols and their potential effect on sunflower
Kirchhof, Gunnar (1994). Compaction properties of vertisols and their potential effect on sunflower. PhD Thesis, School of Land, Crop and Food Sciences, The University of Queensland. doi: 10.14264/uql.2015.469
(2023–2026) GRDC - PROC-9176764 - Understanding crop development and yield responses to mitigate high soil strength in Australian soils.
(2022–2024) Future Drought Fund: Drought Resilient Soils and Landscapes Grants
Sustaining soil fertility in support of intensification of sweetpotato cropping systems
(2016–2024) Australian Centre for International Agricultural Research
(2013) Australian Centre for International Agricultural Research
Assessment of Soil Management Options under Power Line Easements
(2008–2014) Powerlink Queensland (Government Entity)
Soil fertility management in the PNG highlands for sweet potato based cropping systems
(2007–2013) Australian Centre for International Agricultural Research
(2005–2006) Australian Centre for International Agricultural Research
Upland Farming Better Practice Workshop - Bohol Central Visayas, Philippines
(2005) Australian Centre for International Agricultural Research
Sustainable urban water - schemes and technologies - Phase 1 and 2A.
(2004–2006) CRC Water Quality Treatment
Atrazine residues in Australian subtropical soils
(2004) University of Queensland Research Development Grants Scheme
Conservation tillage and its potential to affect catchment salt and water balances
(2003–2006) ARC Linkage Projects
Land disposal as a final treatment for saline industrial effluent
(2002–2004) ARC Linkage Projects
Assessment of spatial variability of soil properties
(2002–2003) UQ New Staff Research Start-Up Fund
An investigation into the chemical, physical and biological properties of manufactured soil produced from bauxite residue
Doctor Philosophy — Associate Advisor
Other advisors:
Nitrogen and root zone temperature effects on sweetpotato cultivation on large mounds
(2018) Doctor Philosophy — Principal Advisor
Improving the capacity to represent surface runoff processes in rangeland biophysical models
(2014) Doctor Philosophy — Principal Advisor
The potential of Australian bermudagrasses (Cynodon spp.) for vegetating hostile soils
(2016) Doctor Philosophy — Associate Advisor
Other advisors:
The water and salt balance of a land disposal system for highly saline industrial effluent
(2014) Doctor Philosophy — Associate Advisor
Sources, mobility and fate of salts in soils of the Queensland Murray-Darling Basin
(2013) Doctor Philosophy — Associate Advisor
Long-term productivity of Leucaena (Leucaena Leucocephala) - Grass pastures in Queensland
(2010) Doctor Philosophy — Associate Advisor
Subsoil constraints to root growth and water use efficiency in northern grain soils
(2010) Doctor Philosophy — Associate Advisor
Other advisors:
THE HYDROLOGY OF SEPTIC TANK - SOIL ABSORPTION SYSTEMS: INVESTIGATION AND PREDICTION OF HYDRAULIC FAILURE
(2007) Doctor Philosophy — Associate Advisor
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.
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.