Biochar application to soil has drawn much attention as a strategy to sequester atmospheric carbon in soil ecosystems. The applicability of this strategy as a climate change mitigation option is limited by our understanding of the mechanisms responsible for the observed changes in greenhouse gas emissions from soils, microbial responses, and soil fertility changes. We conducted an 8-wk laboratory incubation using soils from PASTURE (silt loam) and RICE PADDY (silt loam) sites with and without two types of biochar (biochar from swine manure [CHAR-M] and from barley stover [CHAR-B]). Responses to addition of the different biochars varied with the soil source. Addition of CHAR-B did not change CO and CH evolution from the PASTURE or the RICE PADDY soils, but there was a decrease in NO emissions from the PASTURE soil. The effects of CHAR-M addition on greenhouse gas emissions were different for the soils. The most substantial change was an increase in NO emissions from the RICE PADDY soil. This result was attributed to a combination of abundant denitrifiers in this soil and increased net nitrogen mineralization. Soil phosphatase and N-acetylglucosaminidase activity in the CHAR-B-treated soils was enhanced compared with the controls for both soils. Fungal biomass was higher in the CHAR-B-treated RICE PADDY soil. From our results, we suggest CHAR-B to be an appropriate amendment for the PASTURE and RICE PADDY soils because it provides increased nitrogen availability and microbial activity with no net increase in greenhouse gas emissions. Application of CHAR-M to RICE PADDY soils could result in excess nitrogen availability, which may increase NO emissions and possible NO leaching problems. Thus, this study confirms that the ability of environmentally sound biochar additions to sequester carbon in soils depends on the characteristics of the receiving soil as well as the nature of the biochar.

Background: Soil microorganisms play key roles in nutrient cycling and are distributed throughout the soil profile. Currently, there is little information about the characteristics of the microbial communities along the soil depth because most studies focus on microorganisms inhabiting the soil surface. To better understand the functions and composition of microbial communities and the biogeochemical factors that shape them at different soil depths, we analyzed microbial activities and bacterial and fungal community composition in soils up to a 120 cm depth at a fallow field located in central Korea. To examine the vertical difference of microbial activities and community composition, β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminidase, and acid phosphatase activities were analyzed and barcoded pyrosequencing of 16S rRNA genes (bacteria) and internal transcribed spacer region (fungi) was conducted. Results: The activity of all the soil enzymes analyzed, along with soil C concentration, declined with soil depth. For example, acid phosphatase activity was 125.9 (± 5.7 (± 1 SE)), 30.9 (± 0.9), 15.7 (± 0.6), 6.7 (± 0.9), and 3.3 (± 0.3) nmol g −1 h −1 at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively. Among the bacterial groups, the abundance of Proteobacteria (38.5, 23.2, 23.3, 26.1,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], and 90-120 cm soil depths, respectively) and Firmicutes (12.8, 11.3, 8.6, 4.3,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], and 90-120 cm soil depths, respectively) decreased with soil depth. On the other hand, the abundance of Ascomycota (51. 2, 48.6, 65.7, 46.1, and 45.7% at 15, 30, 60, 90, and 120 cm depths, respectively), a dominant fungal group at this site, showed no clear trend along the soil profile. Conclusions: Our results show that soil C availability can determine soil enzyme activity at different soil depths and that bacterial communities have a clear trend along the soil depth at this study site. These metagenomics studies, along with other studies on microbial functions, are expected to enhance our understanding on the complexity of soil microbial communities and their relationship with biogeochemical factors.

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The anticancer activity of ginseng originated mainly from lipid-soluble components. The hexane extract of ginseng marc (HEGM) showed a potent inhibitory activity on human hepatoma (HepG2, GI 50 = 41.7 lg/ml) and breast (MCF-7, GI 50 = 54.4 lg/ml) cancer cell proliferation in vitro in a concentration-dependent manner as did the hexane extract of ginseng (HEG), with GI 50 values of 21.1 lg/ml in HepG2 and 41.2 lg/ml in MCF-7. The water extract of ginseng (WEG) possessed a low anticancer activity against both cancer cell lines, but the hexanesoluble fraction of WEG (HSF/WEG) showed a potent anticancer activity against HepG2 (GI 50 = 38.7 lg/ml) and MCF-7 cells (GI 50 = 51.1 lg/ml). The hexane extraction in ginseng was a very promising protocol for the maximum recovery of the anticancer active components in high concentrations. Also the adoption of hexane extraction after water extraction of ginseng was successful in the effective utilization of the residual lipid-soluble anticancer active components in ginseng marc.

The seasonal dynamics of soil organic carbon (SOC) fractions and dry aggregates were investigated to determine whether aggregate turnover rates explain the variable influence of no‐till (NT) practices on SOC accrual in Illinois. Soils were collected (0–15 cm) of two 17‐yr‐old trials where NT and conventional tillage (CT) practices had variable effects on SOC sequestration in the 0‐ to 30‐cm depth. Soil was fractionated into loose particulate organic matter (LPOM), macroaggregate‐occluded particulate organic matter (OPOM), and humified fractions (HFs) associated with microaggregates and minerals. Dry aggregate mean weight diameter (DMWD) was used to evaluate structure expressed in the field. Within‐season changes in fraction concentrations indicate that C derived from LPOM and plant roots was transferred to OPOM at both sites. At DeKalb (silty clay loam), NT practices had less influence on SOC sequestration than at Monmouth (silt loam). DeKalb HF contents increased under NT while OPOM contents were unchanged. At Monmouth, NT practices increased SOC sequestration by increasing OPOM concentrations. Site‐based differences in SOC accrual were related to aggregate turnover rates, which were increased by NT practices at Monmouth but were unaffected by tillage at DeKalb. Trends in DMWD and aggregate turnover suggest that when aggregate turnover is slow, as at DeKalb, OPOM formation is limited. Slow turnover in the heavier soil permitted accumulation of HF because residues had longer contact times with particle surfaces. When aggregate turnover is faster, as in the Monmouth NT soil, there is greater chance for residue incorporation into aggregates and accumulation of OPOM. Rapid aggregate turnover limits opportunities for mineral affiliation and HF accrual. Aggregate dynamics predicted site‐based differences in the form and rate of SOC accrual caused by the use of NT practices.

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