Background: The objective of this study was to estimate the carbon sequestration in soils cooperated with organic composts and bio-char during corn cultivation. Methods and Results: For the experiment, the soil texture used in this study was clay loam, and application rates of chemical fertilizer and bio-char were 230-107-190 kg•ha −1 (N-P2O5-K2O) as recommended amount after soil test and 0.2% to soil weight. The soil samples were periodically taken at every 15-day intervals during the experimental periods. The treatments consisted of cow compost, pig compost, swine digestate from aerobic digestion system, and their bio-char cooperation. For estimating soil C sequestration, it is determined by the net balance between carbon inputs and outputs during corn cultivation periods. For the experimental results, it found that applications of aerobic swine digestate, cow compost, and pig compost could sequester C by 38.9%, 82.2% and 19.7% in soil, respectively, when bio-char from rice hulls was cooperated with soil. For plant responses, application of bio-char in the corn field for carbon sequestration was not occurred the damage of corn growth. Conclusion: When bio-char from rice hulls was cooperated with soil, applications of aerobic swine digestate, cow compost, and pig compost could sequester C by 38.9%, 82.2% and 19.7% in soil, respectively. Therefore, addition of bio-char with organic composts could have a potential soil C sequestration in agricultural practices.

BACKGROUND: Currently, national biomass inventory are being established for efficient management of the potential energy sources. Among the various types of biomass, agricultural wastes are considered to take the biggest portion of the total annual biomass generated in Korea, implying its importance. However, the currently estimated amount is not reliable because the old reference data are still used to estimate total annual amount of agricultural wastes. METHODS AND RESULTS: Therefore, to provide reliable estimation data, a correct conversion factor obtained by taking into account the current situation is required. For this, the current study was conducted to provide the conversion factors for each representative 8 crop through a field cultivation study. Also conversion factors for 18 crops were calculated using the average amount of each crop produced during 2004 and 2008, subsequently; total amount of agricultural wastes generated in 2009 was estimated using these conversion factors. The total biomass of rice straw and rice husk generated in 2009 were 6.5 and 1.1 million tons, respectively, which consist 75% of the total agricultural based wastes, while the total

This study was conducted to investigate the optimum conditions for efficient methane production through anaerobic digestion of pig waste slurry. The examined parameters were organic matter content of the pig slurry, the ratio of seed sludge to pig slurry, and stirring intensity of the digestion reactor. The effects of types of slurry produced from different purpose-based pigs fed with different feeds were also tested. The methane concentration in the produced biogas was 45% when the ratio of seed sludge to pig slurry was 50% and total solid (TS) concentration was 1%, and it increased in proportional to TS concentration increases from 3 to 7%. At 3 and 5% of TS concentration, increasing mixing velocity from 80 to 160 rpm resulted in higher biogas production amount. However, mixing amount of seed sludge did not cause any significant effect on biogas production. Overall, the most efficient biogas production was achieved at 3-5% TS concentration in combination with 50% seed sludge inoculation and mixing velocity at 120 rpm. Among pig slurry types, gestating sow waste slurry showed the highest biogas production probably due to higher the degradation rate than other types of pig waste slurry being affected by the feeds components.

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