Carbon dioxide (CO2) and nitrous oxide (N2O) emissions from soil are expected to vary with type of nitrogen fertilizer used. Biochar has recently been proposed as a potential solution to mitigate climate change by reducing greenhouse gas emissions from soils. Incubation experiment was conducted to investigate the effect of different types of biochar on CO2 and N2O emissions when different nitrogen fertilizers used in upland soil. The treatment consisted of different nitrogen fertilizers such as urea, ammonium sulfate and oil cake, and three types of biochars from pear branch, rice hull and soybean stalk. Soil moisture content was adjusted to 70% of the water holding capacity at 25°C. CO2 and N2O gases were collected and analyzed. The cumulative CO2 emissions were 119.4 g m -2 for urea, 107.1 g m -2 for ammonium sulfate, 381.5 g m -2 for oil cake, 137.1 -154.8 g m -2 for urea + biochars, 114.4 -161.5 g m -2 for ammonium sulfate + biochars, and 396.9 -416.4 g m -2 for oil cake + biochars. The cumulative N2O emissions were 216.6 mg m -2 for urea, 44.2 mg m -2 for ammonium sulfate, 347.7 mg m -2 for oil cake and 123.7 -208.3 mg m -2 for urea + biochars, 39.1 -114.9 mg m -2 for ammonium sulfate + biochars and 108.9 -184.2 mg m -2 for oil cake + biochars. No significant differences were observed in N2O emissions among biochar types, except for the mixture of soybean stalk biochar and ammonium sulfate. However, N2O emission was related to both biochar input amount and nitrogen fertilizer types. In particular, N2O reduction effect was great in the addition of biochar when oil cake is mixed into soil. It is considered that further long term field study is needed to apply the biochar use in farming practices.

Biochar application has been considered as a promising solution to address the effects of modern agriculture on climate change. However, there is a lack of research on the biochar application of greenhouse gas emissions based on poor soils in Korean agricultural land. Therefore, this study aimed to evaluate the effects of biochar application according to different soil characteristics on soil organic carbon (SOC) improvement and greenhouse gas reduction. The incubation experiments were conducted for 49 days and used different feedstock (barley straw and poultry manure) and biochar application rates (0, 5, 10, and 20-ton ha−1) in four soil characteristics (upland, U; greenhouse, G; converted land, C; reclaimed land, R). The results of this study showed that the SOC increased significantly in all soils after biochar application. The increasing SOC rate was the highest in poor soil. Biochar 20-ton ha−1 treatment significantly reduced N2O emissions by 33.2% compared with the control. Barley straw biochar significantly reduced N2O emissions from all soils. Barley straw biochar decreased approximately 74.5% of N2O emissions compared with poultry manure biochar. Poultry manure biochar improved SOC and reduced N2O emissions in poor soil. However, in poultry manure biochar treatment in U and G soil, N2O emissions increased. In conclusion, barley straw biochar application was found to suppress N2O emissions and improve the SOC in all soil characteristics of agricultural land. In addition, the soil carbon storage effect and N2O reduction effect of biochar were the highest in poor soil. Thus, the biochar application can be a potential agricultural practice for improving soil quality and decreasing N2O emissions in domestic agricultural soil.

Recently, biochar-related research using agricultural by-products has been actively conducted as part of a response to climate change. However, the effect research of reducing greenhouse gas emissions by the application of biochar by soil type in Korea is still insufficient. Thus, the purpose of this study was to evaluate the greenhouse gas reduction effect according to the application level of biochar by soil type. Closed chamber experiments were carried out for 42 days. The closed chamber experiment was performed by applying a different input amount biochar (0, 5, 10 and 20 ton ha -1 ) by four soil types (upland soil, greenhouse soil, converted soil, reclaimed soil). The cumulative carbon dioxide (CO 2 ) emission decreased by 21.1 -25.7% on average in greenhouse soil, converted soil, and reclaimed soil, but there was no significant difference. It was analyzed that the cumulative nitric oxide (N 2 O) emission decreased significantly by 43.7 -72.1% on average compared to the control group. All four soil types were analyzed to have low N 2 O emissions in the treatment chamber to which 20 ton ha -1 of biochar was applied. Long-term monitoring studies related biochar that can suppress nitrous oxide emissions and increase crop production are considered to needed for sustainable agriculture.

This study was conducted to provide low carbon farming technique for greenhouse gases(GHGs) emission reduction in agriculture sector. It reviewed literatures on the characteristic of cultivation technique and its effects on carbon emission reduction. The effects of GHGs emission reduction were evaluated in agricultural land with several farming practices. In the rice cultivation technique, the irrigation water management showed good effect on GHGs emission reduction in paddy field. It also evaluated reduction efficiency of source of nitrogen supply and soil improvement. The intermittent irrigation showed 25.1% carbon reduction efficiency as compared to continuously flooded treatment. Slow release fertilizer and ammonium sulphate decreased carbon emission by 19.8% and 7.9% compared to urea, respectively. With soil amendments treatment, silicate fertilizer and zeolite reduced carbon emission 14.1% and 21.7% compared to rice straw treatment. In the upland crop cultivation technique, the efficiency of tillage management, green manure, livestock compost and nitrification inhibitor application were estimated. Substitution of 50% of nitrogen with hairy vetch showed 65.6% carbon reduction efficiency. It also showed 20.4% emission reduction with nitrification inhibitor treatment. However, GHGs emission were increased with livestock compost application. It provided basic data for reducing the GHGs emission in agriculture sector by accomplishing low carbon farming technique and policy project.

BACKGROUND: Biochar is a solid material converted from agricultural biomass such as crop residues and pruning branch through pyrolysis under limited oxygen supply. Biochar consists of non-degradable carbon (C) double bonds and aromatic ring that are not readily broken down by microbial degradation in the soils. Due to the recalcitrancy of C in biochar, biochar application to the soils is of help in enhancing soil carbon sequestration in arable lands that might be a strategy of agricultural sector to mitigate climate change. METHODS AND RESULTS: Data were collected from studies on the effect of biochar application on soil C content conducted in East Asian countries including China, Japan and Korea under different experimental conditions (incubation, column, pot, and field). The magnitude of soil C storage was positively correlated (p < 0.001) with biochar application rate under field conditions, reflecting accumulation of recalcitrant black C in the biochar. However, The changes in soil C contents per C input from biochar (% per t/ha) were 6.80 in field condition, and 12.58 in laboratory condition. The magnitude of increment of soil C was lower in field than in laboratory conditions due to potential loss of C through weathering of biochar under field conditions. Biochar production condition also affected soil C increment; more C increment was found with biochar produced at a high temperature (over 450℃). CONCLUSION: This review suggests that biochar application is a potential measures of C sequestration in agricultural soils. However, as the increment of soil C biochar was affected by biochar types, further studies are necessary to find better biochar types for enhanced soil C storage.