Animal manure has been widely used for amended arable soil is a strategy of increasing crop yield. On the other hand, animal manure containing N and C are applied to arable soil can generated greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from soil into atmosphere through microbial activity. Especially, the emissions of N2O are 4.3?5.8 Tg N2O?N year?1, 23%?31% of which originates from agricultural soil because of nitrogen (N) fertilization. The Food and Agriculture Organization (FAO) of the United Nations reported that global annual N production from animal manure was 115 Tg N year?1 in 2017 and that 23.5% (27 Tg N year?1) of annual N production from animal manure was applied to agricultural soil. The global warming potential of N2O is 298 times greater than that of CO2 can deplete stratosphere ozone layer. It is critical to reduce environmental pollution without compromising food security in the context of an increasing worldwide population. Although reduction in N application rates may be an effective means of reducing N2O emissions, this may come at the cost of decreased yields depending on the level of fertilizer input before any change. Alternative practice such as optimization of N input source could reduce N2O emissions without necessarily reducing N application rates or crop yields. Most previous studies estimating GHG emissions from arable soil in which composted animal manure has been due to without considering the obtained high productivity. The first part of the dissertation is nitrogen and carbon in different animal manures on N2O emission from upland soil. The second part describes the effects of different types and application rates of composted animal manure on N2O emission and sweet potato yields from upland soil. The last part of dissertation is the effect of type and rate of animal manure on greenhouse gas intensity (GHGI) from upland soil. The details of the abstracts are presented as follows:
The first study was carried out on upland soils amended with different types of composted animal manure. Field trials were established at Miryang in South Korea during the sweet potato (Ipomoea batatas) field over 3 years: 2016 (Year 1), 2017 (Year 2) and 2018 (Year 3). Three composted animal manures (chicken, cow, and pig) were applied at the rates of 0, 10, and 20 Mg ha?1 to upland soils. In three years, the cumulative N2O emissions increased with increasing rate of application of composted animal manures. Cumulative N2O emission rates depended on the type of animal manure and might be governed by NH4+ concentration, rather than total N concentration in animal type. The SOC concentration affected N2O emission rather than DOC. These results suggest that soil management for N and C containing of animal manure, application rate of animal manure, and %WFPS of soil should be considered to mitigate N2O emissions from cropping systems in upland soil.
The second study was incorporated to on upland soils amended with different types of composted animal manure and located at two geographically different regions of South Korea. Field trials were established at Miryang and Yesan in South Korea during the sweet potato (Ipomoea batatas) on growing season 2 years: 2017 (Year 1) and 2018 (Year 2). Three composted animal manures (chicken, cow, and pig) were applied at the rates of 0, 10, and 20 Mg ha?1 to upland soils in both locations. In growing season of two years and locations, the cumulative N2O emissions increased with increasing rate of application of composted animal manures. Cumulative N2O emission rates depended on the type of animal manure pig manure was the greatest cumulative N2O emission. Sweet potato yields were greater with chicken and cow manure than that with pig manure at both locations. Mean values of yield scaled N2O emission were greatest with pig manure at both locations. Mean values of yield scaled N2O emission increased with increasing rate at both locations. Therefore, estimation N2O emissions from arable soil in which composted animal manure has been due to considering the obtained high productivity.
The last study was performed on upland soils amended with different types of composted animal manure. Field trials were demonstrated at Miryang in South Korea during the sweet potato (Ipomoea batatas) field over 2 years: 2017 (Year 1) and 2018 (Year 2). Three composted animal manures (chicken, cow, and pig) were applied at the rates of 0, 10, and 20 Mg ha?1 to upland soils. For future sustainable agriculture and food security should be to reduce GHG emissions while ability to increase crop productivity, net GWP must be compared to the crop yield. GHGI can provide a good idea for management practice to enhance productivity without increasing GHG emissions which is computed by dividing net GWP by the crop yield.