Agronomic and greenhouse gas assessment of land applied anaerobically digested swine manure
Management of animal wastes from intensive livestock operations (ILO) must be economically feasible, environmentally friendly and socially acceptable. Anaerobic digestion is a promising technology that could provide an option for managing animal waste that may reduce greenhouse gas emissions by utilizing the biogas produced during digestion to displace fossil-fuels and by reducing emissions during lagoon storage. A three-year study was conducted at two locations, Swift Current and Melfort, to compare the agronomic performance and gaseous N loss of land-applied anaerobically digested swine manure (ADSM) to conventionally treated swine manure (CTSM). Treatments included spring and fall applications of CTSM and ADSM at a 1x rate (10,000 and 7,150 L ha-1 respectively) applied each year, and a 3x rate (30,000 and 21,450 L ha-1 respectively) applied once at the beginning of the study. A treatment receiving commercial fertilizer (UAN) and a check (no N) were also included. Nitrogen use efficiency for single applications of ADSM or CTSM at the 3x rate were lower than three annual applications at the 1x rate, while UAN was intermediate. Nitrogen use efficiency of ADSM and CTSM applied in the fall was equal to spring when applied at 1x rate and, in general, agronomic performance of ADSM was similar or better than CTSM. Ammonia loss from ADSM was similar to CTSM, except for CTSM at the 3x rate applied in the fall at Melfort and in the spring at Swift Current, which had significantly higher losses than all other treatments. The percentage of applied N lost as N2O measured at the Melfort site was generally higher for treatments receiving CTSM compared to ADSM or UAN, and losses from ADSM and UAN were similar. The results from this study suggest that ADSM is equal or better than CTSM in terms of agronomic performance, but has lower environmental impact with respect to gaseous N loss.
nitrogen use efficiency
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