Soil test phosphorus and nitrate adjacent to artificial and natural cattle watering sites in southern Alberta

Off-stream watering troughs may reduce surface water pollution by keeping nutrients away from natural water bodies, but may increase nutrient contaminant of groundwater. The objective of this study was to determine to what extent off-stream watering troughs active for 2 to 7 yr caused enrichment and leaching of soil test P (STP) and KCl-extractable NO3-N. The study was conducted in the Lower Little Bow (LLB) River watershed of southern Alberta, Canada. Soil samples were obtained at three recently installed off-stream watering troughs, four active cattle watering sites adjacent to the LLB River, and at two sites along a fenced reach of the river with no cattle access. At each location, samples were obtained along four 100-m transects. Surface (0-5 cm) soil immediately adjacent to the LLB River was not enriched in STP or NO3-N, which was attributed to flushing of nutrients during periods of high flow. Surface soil at distances ≤ 5 m from the three water troughs was approximately three times higher in STP than surface soil obtained at distances ≥10 m and was seven times higher in NO3-N. Subsurface soil layers adjacent (3 m distance) to the three water troughs were not enriched in STP compared with background levels (100 m distance). The subsurface soil adjacent (3 m) to the longest active watering trough was enriched in NO3-N to the 60 cm depth compared with background levels (100 m). Greater nutrient enrichment at the off-stream watering troughs than at the cattle watering sites adjacent to the river suggested that this beneficial management practice (BMP) was effective in shifting nutrient distribution away from the river. Key words: Pasture, nutrient leaching, nitrate, best management practices