Grant: Discovery Grants Program - Individual

Phosphorus (P) is a major water pollutant. Even at low concentrations, P can stimulate algal growth in freshwater bodies. Occurrence of algal blooms impairs water quality. Algal blooms in Lake Winnipeg in Manitoba have increased in size and frequency during the past two decades. Some algal blooms are harmful as they produce toxins. Harmful algal blooms have negatively affected the fisheries industry, wildlife, local indigenous communities, and tourism. Agricultural lands can contribute to excessive P in freshwater bodies. Phosphorus in agricultural soils can get transported to water bodies via different pathways. In the Canadian prairies, the dominant P loss pathway from agricultural lands is the snowmelt runoff. During spring snowmelt, agricultural lands are often flooded for several weeks. It is projected that climate change will increase the severity and frequency of floods. With prolonged flooding, dissolved oxygen in soils gets depleted. This creates anaerobic conditions that can release P from soils to floodwater. Various processes are responsible for the enhanced P loss from flooded soils to overlying water. Management practices commonly adopted to reduce P losses from agricultural lands, are ineffective for regions where spring snowmelt dominates P losses. Therefore, the development of alternative strategies such as soil amendments that reduce P loss are needed for such regions. Soil amendments can convert soil P to less soluble forms and reduce losses. Currently, information on the effectiveness of different soil amendments for reducing P losses with snowmelt flooding is scarce. Research conducted by my research group showed that amendments such as alum are effective in reducing P loss from flooded soils. The effectiveness varied depending on soil composition as well as the type and amount of amendment used. More information is needed to guide farmers on optimum use of soil amendments to reduce P losses. For the proposed research program, I will build on this knowledge to evaluate gypsum, alum, and magnesium sulphate in reducing P loss during snowmelt. I will investigate their effectiveness when applied at different rates to soil, as well as when amendments are used individually or mixed. Research will be conducted in the laboratory under simulated snowmelt flooding and in field. Influence of soil properties on the amendment effectiveness will be explored. The changes in soil P composition, soil properties and microbial diversity with amendments will also be monitored. Using this information, I will elucidate the chemical and physical mechanisms responsible for mitigating P loss with amendments. Based on the findings, I will develop a software tool to optimize amendment applications. The new information generated, and the software tool will be critical for reducing P loss during snowmelt from agricultural lands to waterways. Through these efforts, the proposed research program will help to protect our valuable inland water resources.