- Soil Science Lab, Division of Applied Life Sciences, Gyeongsang National University, Jinju, Korea
- 01097581975
- I am interested in discovering the tiny microorganisms which are involved in deciding the global climate change. In s... moreI am interested in discovering the tiny microorganisms which are involved in deciding the global climate change. In short impact of soil microbial impact on changing the global climate changeedit
A B S T R A C T Soil heterotrophic respiration (SHR) increases exponentially with temperature and this general information has been incorporated into soil carbon models. However, the positive feedback of warming to SHR remains uncertain ,... more
A B S T R A C T Soil heterotrophic respiration (SHR) increases exponentially with temperature and this general information has been incorporated into soil carbon models. However, the positive feedback of warming to SHR remains uncertain , mostly due to the differential response of soil microbial community to warming under dry and flooded conditions in a rice mono-cropping system. In this study, we aimed to evaluate the relationship between SHR and microbial functional groups during the fallow and flooded rice cultivation seasons under changing temperature in a rice mono-cropping system. Field experiments were conducted to investigate SHR, soil microbial functional groups and biomass, and temperature sensitivity of SHR (Q 10) under dry fallow conditions during the cover cropping season and under flooded conditions during the rice cropping season. We found that SHR increased with increasing air and soil temperature, carbon availability, and soil microbial community composition and biomass in the fallow season, whereas a decrease in SHR in spite of an increase in temperature and carbon availability was observed under flooded conditions during the rice cropping season. Furthermore, a nonlinear response of microbial community composition and biomass with SHR was noticed during the flooded rice cropping season. This suggests that flooding could be the limiting factor for temperature sensitivity of SHR as well as microbial community composition in a rice mono-cropping system. Flooding the soil significantly (p < 0.01) decreased Q 10. We therefore conclude that temperature, moisture region and carbon availability, rather than only soil microbial community composition are responsible for the spatiotemporal variation in SHR in a rice mono-cropping system in this region.
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A B S T R A C T Over the past decades, with increasing steel manufacturing, the huge amount of by-products (slags) generated need to be reused in an efficient way not only to reduce landfill slag sites but also for sustainable and... more
A B S T R A C T Over the past decades, with increasing steel manufacturing, the huge amount of by-products (slags) generated need to be reused in an efficient way not only to reduce landfill slag sites but also for sustainable and eco-friendly agriculture. Our preliminary laboratory study revealed that compared to blast furnace slag, electric arc furnace slag and ladle furnace slag, the Linz-Donawitz converter (LD) slag markedly decreased CH 4 production rate and increased microbial activity. In the greenhouse experiment, the LD slag amendment (2.0 Mg ha −1) significantly (p < 0.05) increased grain yield by 10.3–15.2%, reduced CH 4 emissions by 17.8–24.0%, and decreased inorganic As concentrations in grain by 18.3–19.6%, compared to the unamended control. The increase in yield is attributed to the increased photosynthetic rates and increased availability of nutrients to the rice plant. Whereas, the decrease in CH 4 emissions could be due to the higher Fe availability in the slag amended soil, which acted as an alternate electron acceptor, thereby, suppressed CH 4 emissions. The more Fe-plaque formation which could adsorb more As and the competitive inhibition of As uptake with higher availability of Si could be the reason for the decrease in As uptake by rice cultivated with LD slag amendment.
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A B S T R A C T Urea [(NH 2) 2 CO] is synthesized by combining ammonia (NH 3) and carbon dioxide (CO 2). The consumption of atmospheric CO 2 for urea production was considered carbon (C) removal by the Industrial Processes and Product Use... more
A B S T R A C T Urea [(NH 2) 2 CO] is synthesized by combining ammonia (NH 3) and carbon dioxide (CO 2). The consumption of atmospheric CO 2 for urea production was considered carbon (C) removal by the Industrial Processes and Product Use sector. Based on this evaluation, the Intergovernmental Panel on Climate Change proposed a default value (0.2 kg C per kg urea) for the CO 2 emission factor from urea, which is equivalent to the mass percent of C in urea. However, all the C in urea might not be discharged to the atmosphere during the cropping season because some bicarbonates can be released from agricultural fields. To estimate the direct CO 2 emission factor, different levels of urea were applied to cultivate red pepper and garlic during the warm and cold seasons, respectively, and CO 2 emission rates were monitored during the cropping seasons. The seasonal CO 2 fluxes increased significantly with increasing urea application levels, reaching maximum values of 268–273 and 233-250 kg N ha −1 for red pepper and garlic, respectively, and clearly decreased thereafter. Calculated by linear regressions between urea application levels and seasonal 13 CO 2 fluxes originating from 13 C-urea, the direct CO 2 emission rates from urea were projected to be 0.062–0.063 and 0.050–0.052 kg C per kg urea for red pepper and garlic cultivation, respectively. Thus, we suggest revising the current IPCC default value (0.2 kg C per kg urea) for the CO 2 emission factor from urea to be approximately 0.06 and 0.05 kg C per kg urea for warm and cold cropping seasons, respectively, in temperate upland soils.
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In temperate rice paddy fields, winter cover cropping and its biomass application are strongly recommended to increase soil organic carbon (SOC) stock and decrease global warming potential (GWP). However, its biomass application may... more
In temperate rice paddy fields, winter cover cropping and its biomass application are strongly recommended to increase soil organic carbon (SOC) stock and decrease global warming potential (GWP). However, its biomass application may increase greenhouse gas (GHG) emissions, particularly methane (CH 4), during flooded rice cultivation. To evaluate the effect of cover cropping and its biomass application on the annual net GWP in a mono-rice cultivation system, we evaluated the emission rates of CH 4 , nitrous oxide (N 2 O), and carbon dioxide (CO 2) under different cover cropping during the fallow and rice-growing seasons. In cover cropping treatments, barley, hairy vetch, and a barley and hairy vetch mixture were cultivated as winter cover crops without fertilization during the fallow season. Moreover, the total aboveground biomass was incorporated as a green manure one week before rice transplanting. The recommended levels of chemical fertilizers were applied for rice cultivation in the control treatment (NPK) for comparison. The emission rates of CH 4 , soil respiration, and N 2 O gases were simultaneously monitored once a week using the closed-chamber method. However, the soil respiration fluxes included only soil respiration and excluded soil C sequestration through cover cropping and its biomass recycling. The net ecosystem C budget (NECB), which is defined as the difference between the total organic C input and output, was estimated to ascertain the pure soil respiration emission fluxes by mass balance approach. Finally, the net GWP was compared among treatments for the two cultivation seasons. During the dry fallow season, cover cropping significantly increased the soil respiration, and this treatment mineralized C loss significantly increased the seasonal net GWP. In comparison, the cover crop biomass application as green manure increased the soil C balance (NECB) during the rice growing season but more significantly increased the CH 4 emission. As a result, the cover cultivation and its biomass application greatly increased the annual net GWP scale upon cover cropping rice paddy soil. Therefore, soil management practices that can decrease CH 4 emission during rice cultivation should be adopted in cover cropping of the rice paddy soil.
Rye (Secale cerealis) has been widely cultivated to improve soil quality in temperate paddies. However, its biomass incorporation can significantly increase greenhouse gas emissions, particularly the emission of methane (CH4), during rice... more
Rye (Secale cerealis) has been widely cultivated to improve soil quality in temperate paddies. However, its biomass
incorporation can significantly increase greenhouse gas emissions, particularly the emission of methane
(CH4), during rice cultivation. The chemical composition and productivity of cover crop biomass may vary at different
growing stages. Therefore, nutrient productivity and CH4 production potential might be controlled by
selecting the optimumharvesting stage. To investigate the effect of rye harvesting stage on nutrient productivity
and CH4 production potential, rye was harvested at different growing stages, from the flowering stage to the maturing
stage, for seven weeks. The chemical composition and biomass productivity of rye were investigated. CH4
production was measured by laboratory incubation, and CH4 production potential was estimated to determine
the real impact on CH4 dynamics in rice soils. Rye biomass increasedwith plant maturation, but nutrient productivities
such as N (nitrogen), P2O5, and K2O were maximized at the flowering stage. The contents of cellulose and
lignin increased significantly as plants matured, but the total N, labile organic carbon (C), and hot and cold waterextractable
organic C clearly decreased. Soils were mixed with 0.3% (wt wt−1 on dry weight) air-dried biomass
and incubated to measure the maximumCH4 productivity at 30 °C under flooded conditions. MaximumCH4 productivity
was significantly correlated with increasing labile organic C and protein content, but it was negatively
correlated with total organic C, cellulose, and lignin content. CH4 production potentials were significantly increased up to the pre-maturing stage (220 DAS) and remained unchanged thereafter. As a result, CH4 production
potential per N productivity was the lowest at the late flowering stage (198–205 DAS), which could be the
best harvesting stage as well as the most promising stage for increasing nutrient production and decreasing GHG
emissions in temperate mono-rice paddy soils.
incorporation can significantly increase greenhouse gas emissions, particularly the emission of methane
(CH4), during rice cultivation. The chemical composition and productivity of cover crop biomass may vary at different
growing stages. Therefore, nutrient productivity and CH4 production potential might be controlled by
selecting the optimumharvesting stage. To investigate the effect of rye harvesting stage on nutrient productivity
and CH4 production potential, rye was harvested at different growing stages, from the flowering stage to the maturing
stage, for seven weeks. The chemical composition and biomass productivity of rye were investigated. CH4
production was measured by laboratory incubation, and CH4 production potential was estimated to determine
the real impact on CH4 dynamics in rice soils. Rye biomass increasedwith plant maturation, but nutrient productivities
such as N (nitrogen), P2O5, and K2O were maximized at the flowering stage. The contents of cellulose and
lignin increased significantly as plants matured, but the total N, labile organic carbon (C), and hot and cold waterextractable
organic C clearly decreased. Soils were mixed with 0.3% (wt wt−1 on dry weight) air-dried biomass
and incubated to measure the maximumCH4 productivity at 30 °C under flooded conditions. MaximumCH4 productivity
was significantly correlated with increasing labile organic C and protein content, but it was negatively
correlated with total organic C, cellulose, and lignin content. CH4 production potentials were significantly increased up to the pre-maturing stage (220 DAS) and remained unchanged thereafter. As a result, CH4 production
potential per N productivity was the lowest at the late flowering stage (198–205 DAS), which could be the
best harvesting stage as well as the most promising stage for increasing nutrient production and decreasing GHG
emissions in temperate mono-rice paddy soils.
The aerenchymal transport of oxygen to rice roots has significantly influenced the anaerobic root-zone of flooded paddy soils. Therefore, the visualization of redox dynamics may be useful to characterize rice root oxidation potentials and... more
The aerenchymal transport of oxygen to rice roots has significantly influenced the anaerobic root-zone of flooded paddy soils. Therefore, the visualization of redox dynamics may be useful to characterize rice root oxidation potentials and the dynamics of redox-influenced ions in the root-zone of paddy soils. In order to investigate the interaction between root oxidation potential and Fe uptake of (a) six different rice cultivars (Oryza sativa L.) (Chuchung, Dongjin, Ilmi, Junam, Nampyeong, and Samkwang) were monitored in a flooded paddy soil with the aid of rhizotron experiment throughout the vegetation period, (b) digital images of the root-zone were taken at the important growing stages, and (c) rice Fe uptake was characterized simultaneously. The images were processed by image analysis to display the reduction and oxidation areas in the root zones, and the distinct areas which were colorized due to varying soil redox changes were localized and quantified. Oxidized areas were mainly observed in the surrounding of active roots and in a distinct layer on the soil surface. The selected rice cultivars have shown significantly different root oxidized areas at the same rice growing stage. Root oxidized area was significantly and positively correlated with total Fe content of rice root, but negatively correlated with the inner root Fe content. Rice cultivars having higher root oxidation potential precipitated more Fe on the outer root surface in the form of Fe plaques. In conclusion, digital image analysis is an effective tool for evaluating the oxidizing potential of rice root under anaerobic soil condition.
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The present study was aimed to determine the protective effect of Dalbergia sissoo bark extract (DSME) on diclofenac sodium induced gastric ulcer in experimental rats. Thirty Sprague dawlay rats of either sex weighing 150-250 g were... more
The present study was aimed to determine the protective effect of Dalbergia sissoo bark
extract (DSME) on diclofenac sodium induced gastric ulcer in experimental rats. Thirty Sprague
dawlay rats of either sex weighing 150-250 g were maintained at the primate facility, Quaid-i-
Azam University, Islamabad. These rats were divided in to five groups with six rats in each
group. Group 1 was served as control, while group 2 was given 50 mg/kg b.w diclofenac sodium
orally once a day for 12 days. Group 3 was administered with diclofenac sodium and 200 mg/kg
b.w of the DSME. Group 4 was given diclofenac sodium in combination with 400 mg/kg b.w of
DSME orally. Group 5 was administered only with 400 mg/kg b.w of DSME. After 12 days of
treatment all the rats were sacrificed to collect the serum and gastric content. The
gastroprotective effect was assessed from volume of the gastric juice, pH, free and total acidity
of the gastric juice, the level of reduced glutathione (GSH), TBARS, H2O2, and activities of
enzymic antioxidants; catalase (CAT), glutathione peoxidase (GSH-Px), glutathione-Stransferase
(GST), γ-Glutamyl transferase (γ-GT) in gastric mucosa. The stomach tissues were
used for adherent mucus content and also for the histological examination.
There was significant variation in the mean body weight of the treated groups as
compared to the control group. The results obtained in this study indicated that the activity of
catalase (CAT), peroxidase enzyme (POD), glutathione peroxidase (GSH-Px), glutathione-Stransferase
(GST) and glutathione-S-reductase (GSR), glutathione reductase (GSH) and lipid
peroxides (TBARS) was significantly decreased and the level of γ-GT and hydrogen peroxide
(H2O2) was significantly increased in diclofenac treated group as compared to the control group.
A significant reduction in the gastric volume, free and total acidity of gastric juice and increase
was observed in pH of diclofenac treated group as compared to normal group. Histological
studies confirmed the gastroprotective activity of D. sissoo bark extract.
From the data presented in this study it can be concluded that D. sissoo act as a
gastroprotective agent probably due to its free radical scavenging activity and cytoprotective
nature.
extract (DSME) on diclofenac sodium induced gastric ulcer in experimental rats. Thirty Sprague
dawlay rats of either sex weighing 150-250 g were maintained at the primate facility, Quaid-i-
Azam University, Islamabad. These rats were divided in to five groups with six rats in each
group. Group 1 was served as control, while group 2 was given 50 mg/kg b.w diclofenac sodium
orally once a day for 12 days. Group 3 was administered with diclofenac sodium and 200 mg/kg
b.w of the DSME. Group 4 was given diclofenac sodium in combination with 400 mg/kg b.w of
DSME orally. Group 5 was administered only with 400 mg/kg b.w of DSME. After 12 days of
treatment all the rats were sacrificed to collect the serum and gastric content. The
gastroprotective effect was assessed from volume of the gastric juice, pH, free and total acidity
of the gastric juice, the level of reduced glutathione (GSH), TBARS, H2O2, and activities of
enzymic antioxidants; catalase (CAT), glutathione peoxidase (GSH-Px), glutathione-Stransferase
(GST), γ-Glutamyl transferase (γ-GT) in gastric mucosa. The stomach tissues were
used for adherent mucus content and also for the histological examination.
There was significant variation in the mean body weight of the treated groups as
compared to the control group. The results obtained in this study indicated that the activity of
catalase (CAT), peroxidase enzyme (POD), glutathione peroxidase (GSH-Px), glutathione-Stransferase
(GST) and glutathione-S-reductase (GSR), glutathione reductase (GSH) and lipid
peroxides (TBARS) was significantly decreased and the level of γ-GT and hydrogen peroxide
(H2O2) was significantly increased in diclofenac treated group as compared to the control group.
A significant reduction in the gastric volume, free and total acidity of gastric juice and increase
was observed in pH of diclofenac treated group as compared to normal group. Histological
studies confirmed the gastroprotective activity of D. sissoo bark extract.
From the data presented in this study it can be concluded that D. sissoo act as a
gastroprotective agent probably due to its free radical scavenging activity and cytoprotective
nature.