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Dr. Ivan O'Halloran

Soil Fertility and Nutrient Use Efficiency
Associate Professor


Ph.D. Soil Fertility - University of Saskatchewan
M.Sc. Soil-Plant Relationships - University of Guelph
B.Sc. Chemistry - University of Guelph

Research Interests:

The focus of my research is primarily in the area of soil fertility management and land stewardship. Specific research interests include spatial variability of soil properties and crop yields, the site-specific application of nutrients and their fate (e.g. impact of variable nitrogen fertilization on nitrous oxide emissions), management practices to improve crop utilization of nutrients applied in animal manures while reducing off-site losses of manure constituents, methods of assessing manure phosphorus bioavailability and impact of manure phosphorus applications on phosphorus sorption/desorption in soils. Recent or current projects include:

  • Impact of animal manure type and fertilizer phosphorous on soil phosphorus cycling in an Ontario soil
  • Effect of tillage and timing of liquid manure application on the transport of N, P and bacteria to surface and subsurface waters
  • Determination of some key factors for Ontario's soil P index and effectiveness of manure applications practices for mitigating risk to water resources

Research Associates:

Mike Zink
Agronomy Building
University of Guelph Ridgetown Campus
Phone: 519-674-1500 x63598
Ranee Parajasingham
Phone: 519-824-4120 x58748

Graduate Students:

Chris Duits
M.Sc. Student
School of Environmental Sciences


I teach in the Agriculture Diploma and Environmental Management Diploma programs at Ridgetown Campus. The courses I normally teach include:

Recent Publications and Reports:

2009 Nutrient Management Joint Research Forum Agenda

2009 NM8000 Dunfield

2009 NM8001 Lapen

2009 NM8002 Zhang

2009 NM8003 Fleming Wall

View the complete list of reports by Dr. Ivan O'Halloran on the reports page.

For potential graduate students:

I am looking for students interested in studying the utilization of fertilizers, animal manures and biosolids in agriculturally practical and environmentally sound management systems with particular emphasis on the fate of the applied materials, and the identification of mitigating practices to prevent contamination of water and air resources. Such studies would also include assessment of manures from animals fed modified rations to improve the animal's nutrient utilization and the subsequent impact of such treatments on nutrient management in the field. For more information, please email me.

Page reviewed 03/06/2018