Overwinter transformation and fate of fall-applied manure nitrogen

There is growing evidence that soil nutrient cycling is sustained during the non-growing season in the northern regions of Canada. However, the extent of the transformations and loss of fall-applied manure N is not well documented. The NH4-N fraction of liquid dairy cattle manure, liquid swine manure, and ammonium sulfate was enriched with 15N radioactive isotope, and all N sources were applied to bare sandy loams in early November at sites located in contrasted climate (mean annual temperature 1 to 10°C; mean annual precipitation 300 to 1300 mm; mean snow cover depth <5 to 70 cm).…