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AbstractSweet sorghum bagasse (SSB) is a soil amendment with potential for biofuel production. This study was conducted to determine the appropriate techniques for application of SSB and the effect of incorporation of inorganic fertilizer (IF) on the production of komatuna (Brassica rapa) plants. SSB was applied to the surface of the plant or incorporated into soil. The N fate of IF was evaluated by using 15N-labeled IF. The combination of surface application of SSB and incorporation of IF to soil decreased the N uptake by komatsuna plants but increased dry weight, whereas the incorporation of IF and SSB gave lower komatsuna dry weight than IF treatment alone. Moreover, the application of SSB tended to increase the N distribution from IF to komatsuna with decreased N loss from the plant-soil system. These results showed that surface application of SSB is effective for increasing crop production due to reduction of N loss and improved N use efficiency.

This paper assesses the global emission reduction target of halving CO2emissions by 2050. First, future GDPs with specific uncertainty ranges were developed. The Kaya identity and the developed GDP outlook indicate that halving global CO2emissions by 2050, which corresponds to almost 450 ppm-CO2eq. stabilization, requires an improvement approximately four times as large as the historical CO2intensity improvement rate on average up to 2050, if GDP loss should remain within a few percent of potential baseline GDP. In addition, the global energy-related CO2emission reductions were assessed by using an energy systems model. Marginal abatement cost of CO2is over 470 $/tCO2for halving global CO2emissions by 2050 relative to 2005 even under the lower GDP scenario and technology improvements. Great challenges will have to be met for achieving the 450 ppm-CO2eq. Realistic alternative emission reduction scenarios should be explored in two ways; 1) more innovative technological development than any present imaginable development, and/or drastic social innovations are needed for cheaper carbon costs, e.g., within a few tens of US$ per tonne of CO2, and 2) more modest emission reduction targets, e.g., 550 ppm-CO2eq., and adaptation measures are considered.

In this study, cost-effective technological options to stabilize CO2 concentrations at 550, 500, and 450 ppmv are evaluated using a world energy systems model of linear programming with a high regional resolution. This model treats technological change endogenously for wind power, photovoltaics, and fuel-cell vehicles, which are technologies of mass production and are considered to follow the “learning by doing” process. Technological changes induced by climate policies are evaluated by maintaining the technological changes at the levels of the base case wherein there is no climate policy. The results achieved through model analyses ixnclude 1) cost-effective technological portfolios, including carbon capture and storage, marginal CO2 reduction costs, and increases in energy system cost for three levels of stabilization and 2) the effect of the induced technological change on the above mentioned factors. A sensitivity analysis is conducted with respect to the learning rate.