Anaerobically digested solid beef feedlot manure:

N2O emissions and nutrient (N, P) availability and release


Project leader: Francis Zvomuya, Dept. Soil Science
Grad Student: Waraidzo Chiyoka

Soil scientist Dr. Francis Zvomuya lead the Manitoba contingent of a beef cattle feedlot biogas research project in collaboration with AAFC-Lethbridge and Highmark Renewables Research in Alberta. Alberta has several bio-digesters in operation to supplement other sources of energy generation in the province. The research group quantified indicators of agronomic performance for the digested solid manure (in both loose and pellet form) in relation to synthetic N+P and raw cattle manure. While Francis and his team compared nutrient mineralization and N2O emissions at a laboratory scale, his Lethbridge counterparts took their digested material to the field for larger scale agronomic evaluations.

Published in Animal Feed Science and Technology 166–167 492– 502

Grad Student Thesis Work:

Characterization of nutrient release and greenhouse gas emission from Chernozemic soils amended with anaerobically digested cattle manure
by Waraidzo Chiyoka


Two laboratory incubation studies and a growth room bioassay of forage barley were conducted to investigate nitrogen (N) and phosphorus (P) mineralization, and nitrous oxide emission from two contrasting agricultural soils amended with anaerobically digested cattle manure (ADM). The ADM is a nutrient-rich co-product from manure-based biogas plants which is applied to cropland at rates used for raw manure since scientific information on nutrient release from ADM is lacking. Application of the separated solids fraction of ADM (SS) reduced nitrous oxide emission but resulted in lower N mineralization compared to raw manure in both soils. Raw manure- and SS- treatments had similar biomass yields and P supply capacities while the application of pelletized SS (PSS) caused net N immobilization, lower P release than manure and SS, and depressed barley yields relative to non-amended (control) soils.

Download Full Thesis Paper here (pdf)