Winter feeding beef cattle on the western Canadian prairies: Impacts on soil nitrogen and phosphorus cycling and forage growth

Overwintering beef cows is a major cost in cow-calf production systems on the western Canadian prairies. Winter feeding directly on pasture is a potentially more efficient system in terms of nutrient recycling compared to conventional drylot feeding in a yard. An experiment was conducted from 2003 to 2005 at Lanigan, Saskatchewan, Canada on a Russian wild ryegrass (Psathryrostachys juncea [Fisch.] Nevski) pasture to compare winter feeding hay and straw directly on pasture (bale graze [BG]; bale process [BP]) to conventional feeding in a drylot pen (DL). In the pasture winter feeding systems, stocking density was 2080 cow days ha−1. In the DL system, 67 t ha−1 of raw manure or 22 t ha−1 of compost was hauled out of the yard and mechanically spread on pasture. Soil inorganic nitrogen (N) amounts (0–15 cm) measured the following spring where cattle were winter fed on pasture were 3–3.7 times greater than the unfertilized control treatment, an average increase of 117 kg N ha−1. Soil inorganic N amounts were similar to control where raw manure or compost was spread by equipment. Forage dry matter yields (DMYs) were 3.3–4.7 times greater than control DMY where cattle were fed on the pasture, and 1.4–1.7 times greater than control where raw manure or compost was mechanically spread. Recovery of N and phosphorus (P) in the forage was approximately 30–40% of original feed N and 20–30% of original feed P that was imported into the field in the pasture overwintering systems. For DL feeding 1% of feed N and 3% of feed P was estimated to be recovered in the forage. Greater efficiency in recycling winter feed nutrients into pasture forage growth than drylot feeding appears to be an important benefit of pasture winter feeding systems.