https://doi.org/10.2134/jeq2018.12.0448

Schneider, K. D., McConkey, B. G., Thiagarajan, A., Elliott, J. A., & Reid, D. K. (2019). Nutrient Loss in Snowmelt Runoff: Results from a Long-term Study in a Dryland Cropping System. Journal of environmental quality, 48(4), 831-840. https://doi.org/10.2134/jeq2018.12.0448

Snowmelt runoff often comprises the majority of annual runoff in the Canadian Prairies and a significant proportion of total nutrient loss from agricultural land to surface water. Our objective was to determine the effect of agroecosystem management on snowmelt runoff and nutrient losses from a long-term field experiment at Swift Current, SK. Runoff quantity, nutrient concentrations, and loads were estimated after a change in management from conventionally tilled wheat (Triticum aestivum L.)–fallow (Conv W-F) to no-till wheat–fallow and subsequently no-till wheat–pulse (NT W-F/LP) and to an organic system with a wheat–green manure rotation (Org W-GM). The conversion from conventional tillage practices to no-till increased snowmelt runoff likely due to snow trapping by standing stubble after summer fallow. Relatedly, runoff after no-till summer fallow had higher dissolved P losses (0.07 kg P ha−1). Replacing summer fallow with a pulse crop in the no-till rotation decreased snowmelt runoff losses and nutrient concentrations. The Org W-GM treatment had the lowest P loss after stubble (0.02 kg P ha−1) but had high dissolved P concentrations in snowmelt following the green manure (0.55 mg P L−1), suggesting a contribution from incorporated crop residues. In this semiarid climate with little runoff, dissolved reactive P and NO3–N loads in snowmelt runoff were smaller than those reported elsewhere on the prairies (averaging <0.05 kg P ha−1 yr−1, and <0.2 kg NO3–N ha−1 yr−1); however, the nutrient concentrations we observed, in particular for P, even without P fertilizer addition for organic production, question the practicality of agricultural management systems in this region meeting water quality guidelines.

https://doi.org/10.2134/jeq2018.12.0448