Thesis
Environmental benefits and consequences of field applied anaerobically digested dairy manure for forage production
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/101987
Abstract
Anaerobic digestion (AD) of dairy manure has been shown to reduce environmental challenges associated with land application of animal manures. Although there is extensive research on nutrient and pathogen cycling of non-treated animal manures, information on the use of AD manure is limited. Field and laboratory studies were established to evaluate the effect of AD dairy slurry on forage biomass production, nitrogen uptake, soil nitrate, gaseous nitrogen losses of ammonia and nitrous oxide, and pathogen loading and decay in the environment. We compared AD manure with before-digested dairy slurry (BD) and urea fertilizer. Manures were applied to the subsurface (SSD) or via broadcast (B). Control plots had the lowest crop-nitrogen content and biomass production during 2009 and 2010, while urea had the greatest crop-N and biomass. There were statistical differences between manure types; however they were not agronomically significant. In 2010, the AD-B plots were not significantly different from the urea plots. Urea treatments had the highest apparent nitrogen recovery in 2009 and 2010, with more pronounced differences in 2010. The two manures applied SSD had lower percent nitrogen recovery, indicating that SSD inhibited plant growth. Urea resulted in the highest soil nitrates, while manure treatments were not significantly different. Anaerobically digested manure emitted more N2O (3-4% of applied NH4 + ) than all others. The system was not carbon limited, since BD emitted less N2O and has a greater amount of readily available carbon for denitrifying microorganisms. Urea emitted N2O was low because the water filled pore space was not optimal for denitrification. Treatments receiving BD manure emitted significantly more ammonia per kg of ammonium applied, and there was a benefit in both manures to applying the material to the subsurface. Before application and at the end of the sampling period, AD soils had fewer indicator bacteria than BD soils. Additionally, the rate of die-off was not conclusive different among treatments. We recommend utilizing AD technologies for use in forage production, and to limit pathogen loading to the environment. Utilizing digested manure did not significantly increase nitrogen losses via nitrate leaching or gaseous emissions.
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Details
- Title
- Environmental benefits and consequences of field applied anaerobically digested dairy manure for forage production
- Creators
- Olivia Erica Saunders
- Contributors
- Ann Marie Fortuna (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525288001842
- Language
- English
- Resource Type
- Thesis