Darshani Kumaragamage, Ph.D

Research Activities

My research program focuses on the environmental impact of agricultural practices. Through the application of fundamental chemical and hydrological principles to soil systems, the long term goal is to increase soil productivity and minimize environmental pollution emanating from agricultural activities. My research interests include environmental impact of using synthetic fertilizers and animal manure as plant nutrient sources, transformations and mobility of phosphorus in soils and nutrient management for increased productivity.

1.

Phosphorus release from flooded soils

Phosphorus losses from agricultural soils to water bodies has a potential negative impact on the environment through promoting algal blooms in water bodies, a serious water quality challenge facing Lake Winnipeg. Anoxic conditions resulting from flooding often lead to enhanced release of phosphorus to overlying water, increasing the risk of phosphorus loss to water bodies; however, this effect is not consistent across all soils. We are investigating phosphorus release patterns under temporarily water logged conditions for different soil types in Manitoba that are prone to flooding. Such information is needed to develop best management practices associated with surface and subsurface drainage, to reduce phosphorus mobilization from flooded soils with consequent occurrence of anoxic conditions.

Flood Study

Flood Study

Funding organizations: Manitoba Conservation and Water Stewardship, Agri-Food Research and Development Initiative (ARDI) and University of Winnipeg Major Grant
Collaborators: Dr. Don Flaten (U Manitoba) and Dr. Wole Akinremi (U Manitoba)
Graduate students: Geethani Amarawansha (U Manitoba)
Undergraduate students: Joshua Markham (U Winnipeg)

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2.

Minimizing phosphorus losses from agricultural lands

Accumulation of phosphorus in soils with manure and fertilizer applications increases the risk of phosphorus leaching to groundwater, particularly in sandy soils. We compared the effects of incorporation of manure and fertilizer with tillage on leaching losses of phosphorus in manured and fertilized soils. Incorporation of manure or fertilizer with tillage significantly reduced leaching losses. The results suggest that in areas where phosphorus leaching losses are of particular concern, immediate incorporation of phosphorus sources should be recommended and practiced to reduce phosphorus loadings to groundwater.

Funding organizations: University of Winnipeg
Collaborators: Dr. Wole Akinremi (U Manitoba)
Undergraduate students: Peter Tan (U Winnipeg)

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3.

Phosphorus and metal fractions in solid and liquid separates of liquid swine slurry

Repeated manure applications at rates based on crop nitrogen requirements often leads to an excess of phosphorus, particularly with manures having low nitrogen: phosphorus ratio. Metal accumulation is also a concern with manures having high metal concentrations. Solid-liquid separation is a manure management option for swine slurry whereby nitrogen-rich liquid is separated from phosphorus-rich solid, allowing the liquid separate to be used as an N source to crops without over-supplying P. Different techniques for liquid-solid separation have been developed but their efficiency in partitioning various P and metal fractions to solid and liquid separates has not been studied in detail. We are comparing efficiency of different solid-liquid separation techniques in separating phosphorus and metals to solid separate for swine slurry under Manitoba conditions. Such information is needed in making choices regarding suitable separation methods and to make the best use of separated solid and liquid.

Funding organizations: Manitoba Livestock and Manure Management Initiative (MLMMI)
Collaborators: Dr. Wole Akinremi (U Manitoba), Lorne Grieger (Prairie Agricultural Machinery Institute)
Post-doctoral scholars: Dr. Lekan Solomon Olatuyi

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4.

Improving soil productivity through better nutrient management in agricultural soils of Sri Lanka

Low inherent soil fertility is one of the main contributing factors limiting crop yields in Sri Lanka. In collaboration with the Universities of Sri Lanka, I am involved in training Ph.D. graduate students working towards improving soil productivity in Sri Lanka through different approaches, such as use of improved soil test methods to recommend fertilizers and application of animal manure and biochar to improve soil properties. Prior to initiating field experiments in Sri Lanka, these graduate students are trained on advanced laboratory techniques at the University of Winnipeg.

Funding organizations: Ministry of Higher Education, Sri Lanka and Canadian Bureau of International Education
Collaborating Institutions: Postgraduate Institute of Agriculture, University of Peradeniya, Sri Lanka and Rajarata University of Sri Lanka
Collaborating Scientists: Dr. Srimathie Indraratne
Graduate Students: Don Medige S. Duminda, J. A. Surani Chathurika

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