Nitrogen budget estimated for 908 cow-calf, backgrounding and finishing beef operations across Canada

Beef production plays a significant role in Canadian agriculture in terms of its contribution to total farm cash receipts and management of large tracts of land. The sustainability of the sector has been challenged on several fronts including greenhouse gas and ammonia emissions. An extensive survey of husbandry and agronomic practices in 2011 provided the unique opportunity to compute a detailed nitrogen (N) budget for 908 beef operations of different types from across Canada. The resulting overall-N and commercial-N budgets and overall commercial and beef nitrogen use efficiency (NUE) estimates varied markedly among the types of beef operations. Surprisingly, forage-based cow-calf operations with little importation of commercial N sources often had the largest overall surplus N (N remaining on farms), largely because of symbiotic N fixation of pasture and forage crops, a larger land-base and lower NH3-N emissions compared to confinement housing. These operations had relatively low NUE estimates of about 0.33. In contrast, solely finisher operations had overall N budgets that were not different from zero and NUE of about 0.66. These operations purchase much of their feed and animal nutrition is carefully managed, so the NUE is distinctly higher than in forage-based systems. However, these operations also have high NH3 emissions. Observed regional differences in budgets were related to differences in deposition of atmospheric N and in legume content of forages.