Manure Management Practices: Effective Use of Nutrients From Feedlot Cattle In Alberta.

Alberta is home to 6.5 million head of cattle, 41% of the Canadian total, with most of them raised in confined animal feeding operations (CAFO) in the semiarid southern part of the province. Proper management of the large volumes of manure produced from these CAFOs is vital to both the beef industry and the environment. Most cattle manure from CAFOs is applied to cropland nearby due to the high cost of transportation. Quite often, the amount of N and P applied exceeds crop uptake and removal, causing excessive nutrient accumulation in soil and potential negative impacts on the environment from runoff and leaching losses. In addition, excessive salt accumulation under semiarid conditions and an imbalance of nutrients in heavily-manured soils also reduces crop yield. Increasingly, manure from CAFOs is composted so that nutrients can be transported longer distances than with raw manure. Other composting benefits include reduced odor, weed and pathogen problems associated with raw manure. Anaerobic digestion is another option in managing manure to generate biogas energy from a renewable source. In addition, the digestate by-product from biogas production is rich in nutrients and can be used for crop production (liquid form) or separated and processed into pellets and transported even further (solid form). Feedlot manure N and P nutrient management will be examined using studies conducted at the Lethbridge Research Centre including a long-term (38-yr) land application study, 15 yr of composting research and a 5-yr study examining the agronomic value and greenhouse gas emissions of biogas digestate by-products (liquid, separated solids, pelletized solids).