Nitrogen loss in snowmelt runoff from non-point agricultural sources on the Canadian prairies
Schneider, K.D., Thiagarajan, A., Cade-Menun, B.J., McConkey, B.G. and Wilson, H.F. 2018. Nitrogen loss in snowmelt runoff from non-point agricultural sources on the Canadian prairies. pp. 73-94. In: Lal, R., and Stewart, B.A., eds. Soil Nitrogen Uses and Environmental Impacts. CRC Press. Boca Raton, FL. 392 pp. ebook ISBN: 9781351857413
Plain language summary
Nitrogen (N) is an essential element for crop growth, and many agricultural systems require N fertilizer inputs for optimal crop production. However, only a portion of the applied N from chemical fertilizers or manure is used by plants or stays in soil. Nitrogen can be lost from agricultural landscapes in the gaseous forms, in leaching, and in rainfall or snowmelt runoff. Nitrogen losses in runoff from agricultural sources is a major global concern, and can cause water quality problems in many regions. To reduce N losses and avoid risks water quality problems, it is important to understand management practices that increase or decrease N losses, and the ways N moves from land to water. The Canadian prairies are different from other regions in Canada because most moves in snowmelt runoff in spring, instead of in rainfall runoff throughout the year. This invited book chapter reviews the results of several research projects on the Canadian prairies. In addition to summarizing the results of these projects, it gives recommendations for management practices to reduce N loss in snowmelt runoff, and identifies topics for which knowledge is limited, and where more research is needed.
Nitrogen (N) is an essential element for crop growth, and many agricultural systems require N fertilizer inputs for optimal crop production. However, only a portion of the N applied as chemical fertilizer or manure is used by plants or retained in soil. Nitrogen can be lost from agricultural landscapes through volatilization (as ammonia, NH3), denitrification (in the gaseous forms N2O, NO, N2), in leaching of nitrate (NO3-N), and in rainfall or snowmelt runoff. Nitrogen is transported in runoff in a variety of forms, including soluble inorganic [NO3-N, ammonium-N (NH4-N)], and dissolved organic forms (DON), or particulate-bound organic and inorganic N (Delgado 2002). Nitrogen export to surface water in runoff from agricultural sources is a major global concern; in a worldwide study of 946 watersheds, N losses in runoff were consistently higher per unit area from agricultural than from non-agricultural land. Non-point agricultural sources of nutrients are typically more challenging to manage than point sources because of broader distribution throughout impacted watersheds and because these sources are often highly variable in time due to the role of weather in determining the frequency and intensity of runoff. To improve fertilizer use efficiency and minimize risks to downstream water quality, the pathways of N loss from agriculture must be identified, along with management practices that increase or decrease N losses.