Wetlands: Agricultural Soil & Water Management for a Changing Climate

Wetlands & Agriculture

Like the seasons, there are natural drought-flood cycles where we experience a back and forth between years of little precipitation leading to drought and other years with heavy precipitation that can cause flooding. However, with climate change these weather extremes are expected to be more intense and the patterns may become difficult to predict.

Crop production is especially vulnerable to these extreme drought and flood events because they can cause substantial yield losses or crop failure. My research at the University of Saskatchewan considers how wetlands found in crop fields can act as an agriculture and water management tool that protects farmers against these weather events while also helping to slow climate change.

One strategy that can increase crop production’s resilience to extreme weather is maintaining wetlands within cropland. A wetland is an area of land that is permanently or seasonally flooded with water. In North America, the Prairie Pothole Region features a landscape dominated by depressions known as prairie potholes, sloughs, or wetlands. Prairie potholes are crucial for water management. They act as sponges, collecting water from snowmelt in the spring which saturates the soil. At this time, there is typically a pond of water that can be seen. Later in the summer or in dry years, some wetlands may not have a visible pond as the stored water evaporates or moves to the groundwater. The water storage and groundwater recharge facilitated by this sponge-like action is crucial for both drought resilience and flood mitigation.

During wet or flood years, the wetland area is not accessible for planting crops but acts as a reservoir for excess water on the crop fields. In drought years when there is no wetland pond, crops can be planted in the wetland area. The wetland area will often have higher soil moisture and nutrient contents to support crop growth during the drought period and this can buffer lower crop performance in other parts of the field.

In the Prairie Pothole Region, an estimated 40 to 70 percent of wetlands have been drained. The purpose of drainage is often to increase the land available for agriculture and improve crop production efficiency, especially for land worked with larger machinery. Yet by draining wetlands we lose the water management benefits that they provide.

Prairie Pothole Region map and landscape. Map: Chantel Chizen / Photo: U.S. Fish and Wildlife Service

Wetlands & Soil Carbon Storage

While crop production can adapt to the changing environment, it can also increase soil carbon storage to reduce the effects of climate change. Soil carbon mainly exists as organic matter which is made up of decomposing plant and animal materials. Globally, 80 percent of the carbon stored on land is found in the soil, with the remaining 20 percent found in plants and animals. The carbon that exists in the soil can be lost to the atmosphere as carbon dioxide which is a greenhouse gas that is known for contributing to climate change. To protect or increase soil carbon, we can use management practices, such as no-till or perennial crop production, as well as maintain ecosystems that are excellent at storing lots of carbon in their soils.

Ecosystems such as wetlands and forests have higher soil carbon storage. Wetlands can store large amounts of carbon for two main reasons; the first being high plant productivity which increases organic matter, and the soils are periodically saturated with water which slows the rate of decomposition and allows organic matter to accumulate over time. Keeping wetlands within croplands is a way of increasing carbon storage in agricultural landscapes.

Combining the soil and water perspectives to understand the role of prairie pothole wetlands for carbon storage is the focus of my Ph.D. research. I am measuring soil carbon in prairie potholes wetlands across Saskatchewan, Canada to see if it changes with geography, wetland drainage, and how long water is stored in the wetland after snowmelt. With this dataset, we will improve our estimates of carbon storage in prairie pothole wetlands and learn how wetland drainage can impact soil carbon. This information will provide landowners and policymakers with the resources to make decisions related to wetland management in agricultural landscapes for maintaining our freshwater resources and soil carbon storage.

Visualizing carbon storage in Earth’s ecosystems. Source: Visual Capitalist

Appreciation

As I continue my Ph.D. research, I cannot express enough gratitude for the FFAR Fellows Program. The program’s skill development and mentorship opportunities has empowered me to grow as a professional. This development has been especially helpful to my success as a graduate student since joining in the program and it continues to prepare me for a career in agriculture. I am also grateful for my sponsor, The University of Saskatchewan, and research supervisor Dr. Angela Bedard-Haughn for supporting this project and involvement in the FFAR Fellows Program. This research is made possible by our collaboration with the Saskatchewan Water Security Agency as well as additional funding from the Government of Saskatchewan and Natural Sciences and Engineering Research Council of Canada (NSERC).

Chizen in field.