| dc.contributor.author | Mkhabela, Manasah Sibusiso. | en_US |
| dc.date.accessioned | 2014-10-21T12:33:25Z | |
| dc.date.available | 2007 | |
| dc.date.issued | 2007 | en_US |
| dc.identifier.other | AAINR27647 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/54925 | |
| dc.description | Livestock manure is a valuable source of plant nutrients, however, if poorly managed it can have negative environmental impacts. The major environmental impacts and health concerns associated with manure are the loss of nitrogen (N) in the form of nitrate (NO3), ammonia (NH3) and nitrous oxide (N2O), as well as odour emissions. Laboratory and field experiments were conducted in Truro and Great Village, Nova Scotia to evaluate the effect of several management strategies on NH3, N2O and odour emissions. The strategies evaluated include; (i) use of a nitrification inhibitor (dicyandiamide), (ii) soil liming, (iii) slurry application rate, (iv) soil water status, (v) slurry dilution, and (vi) simulated rainfall soon after slurry application. The study also evaluated the effects of meteorological conditions on NH3, N 2O and odour emissions, for the purpose of identifying the most appropriate conditions under which manure can be applied with minimum emissions. Results showed that dicyandiamide had no effect on either NH3 or N 2O emissions. Liming soil to a pH ≥ 6.3 decreased N2O, but increased NH3 emissions. Generally, N2O emissions from the field experiments were low (∼5 g N ha-1 d-1) even with high (180 t ha-1) slurry application rates. This was due to low soil NO3- -N (<5 mg kg-1 soil) contents caused by slow nitrification activity on these acidic soils. Additionally, estimated indirect N2O emissions (i.e., emissions due to volatilised NH3) were higher than direct emissions. Increasing slurry application rate increased NH3 losses and to a lesser extent odour emissions, but had no effect on N2O emissions. Applying slurry to wet soils increased NH 3 losses by 8% compared to dry soil, but had no effects on N2O and odour emissions. Slurry dilution and simulated rainfall reduced NH 3 losses on average by 41 and 45%, respectively, but had no effect on N2O emissions. With regard to odour, dilution reduced odour emissions on average by 27%, while simulated rainfall increased odour emissions by 15%. Ammonia losses increased with higher air and soil temperature, net radiation, evapotranspiration and vapour pressure deficit, while N2O emissions were not affected by the recorded meteorological variables. Meanwhile, odour emissions increased with higher windspeed, net radiation and evapotranspiration. Both NH3 and odour emissions can therefore, be reduced by applying slurry during cool and calm conditions, however, such conditions may increase odour persistence. The fact that estimated indirect N2O emissions were higher than direct emissions suggests that more effort should be directed towards reducing NH3 losses following application of slurry on these acidic soils. | en_US |
| dc.description | In addition, field experiments were performed from 2003 to 2005 at Streets Ridge (SR), Cumberland County, Nova Scotia and Bio-Environmental Engineering Centre (BEEC), Truro, Nova Scotia to evaluate the impact of tillage on NH 3, N2O, denitrification rates, ratios of denitrification end-products (N2O:N2O+N2), and soil and drainage water NO3--N concentrations following surface application of beef and dairy manure. Over the two seasons, manure incorporation in the conventional tillage (CT) reduced NH3 loss on average by 86% at SR and 78% at BEEC relative to no-tillage (NT). At both sites and both seasons, denitrification rates and N2O emissions in NT were generally higher than in CT. Conversely, N2O:N2O+N2 ratios were lower in NT, indicating more complete reduction of N2O to N2. Similarly, soil and drainage water NO3 --N concentrations were generally lower in NT. Thus, NT can be used to reduce NO3--N leaching to groundwater, albeit with trade-offs. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2007. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Engineering, Agricultural. | en_US |
| dc.title | Gaseous nitrogen and odour emissions following manure application under grassland and cultivated systems. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
