Water-extractable anions in soils and plants are major forms of essential nonmetal nutrients (N, ... more Water-extractable anions in soils and plants are major forms of essential nonmetal nutrients (N, P, S, and Cl) and important for understanding the soil's current nutrient supply conditions and the plant's recent nutrient uptake status. We investigated the compositions of major inorganic anions (nitrate, orthophosphates, chloride, and sulfate) in both soil and plant water extracts obtained from 19 farmlands (5 monocots, 4 tree dicots, and 10 non-tree dicots). We observed that, although there were several important general properties of soil and plant anions, the anionic compositions were mostly inherent characteristics of each soil and varied largely depending on the plant species. A multivariate factor analysis revealed that the anionic compositions of each soil solution were well characterized by their responses to increments of electrical conductivity. In addition, the leaf anion compositions of each plant tended to share similar characteristics within the same plant types (monocots, tree dicots, and non-tree dicots).
Rice (Oryza sativa L.) is one of the most important staple food crops in Southeast Asia, a region... more Rice (Oryza sativa L.) is one of the most important staple food crops in Southeast Asia, a region that is also particularly vulnerable to climate change. We introduced a multi-scale crop modeling approach to assess the impacts of climate change on future rice yields in Southeast Asia. National-and farmer-level adaptation strategies may be developed by combining the advantages from regional-and field-scale crop models. Climate variables collected from the COordinated Regional climate Downscaling EXperiment (CORDEX)-East Asia were used as inputs to run the GLAM-Rice and CERES-Rice crop models. Simulations produced by the GLAM-Rice model identified Cambodia as the country in Southeast Asia where the reduction in rice yields under climate change will be the largest (a decrease of approximately 45% in the 2080s under RCP 8.5, relative to the baseline period 1991-2000) without adequate adaptation. The results of the model simulations considering the CO 2 fertilization effect showed that improved irrigation will largely increase rice yields (up to 8.2-42.7%, with the greatest increases in yields in Cambodia and Thailand) in the 2080s under RCP 8.5 compared to a scenario without irrigation. In addition, the grid cell that will benefit the most (12.6°N and 103.8°E) was identified through further investigation of the spatial distribution of the effects of irrigation for Cambodia. For this grid cell, the CERES-Rice model was used to develop the best combination of adaptation measures. The results show that while a doubled application rate of nitrogen fertilizer (100 kg N ha −1) will increase rice yields by 3.9% in the 2080s under the RCP 4.5 scenario for the Sen Pidao cultivar, a decrease in rice yield was projected for the Phka Rumduol cultivar under RCP 4.5. For both cultivars, the results show that additional adaptation strategies besides the 100 kg N ha −1 fertilizer application rate and planting adjustment should be applied in order to offset all of the negative projected impacts of climate change on rice yields in the 2080s under RCP 8.5. It is concluded that this study can be useful to enhance food security in Southeast Asia by providing informed recommendations for efficacious adaptation strategies.
While electrical conductivity (EC) and sodium adsorption ratio are commonly used to assess soil s... more While electrical conductivity (EC) and sodium adsorption ratio are commonly used to assess soil salinity, for detecting salinity responses during a growing season, those indicators appear to be insensitive when the soils are already high in salinity. We found that the EC and chloride concentrations in soil extracts from salt-affected greenhouses did not show a significant difference in response to different fertilizations of tomato (with a high N demand and a low susceptibility to salinity) and lettuce (the opposite) over the growing season. The fields had been treated with chemical fertilizers or chemical fertilizers plus manure composts combined with food wastes to investigate salinity enhancement by the amendments. On the other hand, the regression lines between EC and chloride concentration could show differential responses in both soil and plant extracts to the doses and salinities of fertilizers. Therefore, using the relationships between EC and associated ions can provide a better insight into the salinity susceptibilities of soils and plants.
Korean Journal of Soil Science and Fertilizer, 2021
Received: November 2, 2021 Revised: November 8, 2021 Accepted: November 8, 2021 ORCID Gwang Hyun ... more Received: November 2, 2021 Revised: November 8, 2021 Accepted: November 8, 2021 ORCID Gwang Hyun Han https://orcid.org/0000-0001-5572-7360 Chloroform fumigation and extraction (CFE) has been a widely accepted method for quantifying overall size of soil microbial community, which is a key indicator to assess the quality and health of a given soil. However, the standard procedure of CFE requires careful operations to generate enough CHCl3 vapors and flush them into soil pores. We suggest a new simple alternative for facilitating gaseous diffusion of CHCl3 molecules under ambient air pressure conditions. The microbial C values by the new approach, examined for several farmland, forest, and grassland soils, coincided well with those obtained by the standard CFE. The cell lysis and extraction coefficient was also close to that of standard CFE and much higher than that evaluated for a liquid-based CHCl3 cell lysis.
Chloride is known as the most important anion in saltaffected soils. We observed the degree of EC... more Chloride is known as the most important anion in saltaffected soils. We observed the degree of EC change upon AgCl precipitation was quantitatively related with the chloride concentration. Method validation and intercomparison with ion chromatography revealed the proposed method can provide rapid and moderately precise chloride concentrations in salt-affected soils.
Water-extractable anions in soils and plants are major forms of essential nonmetal nutrients (N, ... more Water-extractable anions in soils and plants are major forms of essential nonmetal nutrients (N, P, S, and Cl) and important for understanding the soil's current nutrient supply conditions and the plant's recent nutrient uptake status. We investigated the compositions of major inorganic anions (nitrate, orthophosphates, chloride, and sulfate) in both soil and plant water extracts obtained from 19 farmlands (5 monocots, 4 tree dicots, and 10 non-tree dicots). We observed that, although there were several important general properties of soil and plant anions, the anionic compositions were mostly inherent characteristics of each soil and varied largely depending on the plant species. A multivariate factor analysis revealed that the anionic compositions of each soil solution were well characterized by their responses to increments of electrical conductivity. In addition, the leaf anion compositions of each plant tended to share similar characteristics within the same plant types (monocots, tree dicots, and non-tree dicots).
Rice (Oryza sativa L.) is one of the most important staple food crops in Southeast Asia, a region... more Rice (Oryza sativa L.) is one of the most important staple food crops in Southeast Asia, a region that is also particularly vulnerable to climate change. We introduced a multi-scale crop modeling approach to assess the impacts of climate change on future rice yields in Southeast Asia. National-and farmer-level adaptation strategies may be developed by combining the advantages from regional-and field-scale crop models. Climate variables collected from the COordinated Regional climate Downscaling EXperiment (CORDEX)-East Asia were used as inputs to run the GLAM-Rice and CERES-Rice crop models. Simulations produced by the GLAM-Rice model identified Cambodia as the country in Southeast Asia where the reduction in rice yields under climate change will be the largest (a decrease of approximately 45% in the 2080s under RCP 8.5, relative to the baseline period 1991-2000) without adequate adaptation. The results of the model simulations considering the CO 2 fertilization effect showed that improved irrigation will largely increase rice yields (up to 8.2-42.7%, with the greatest increases in yields in Cambodia and Thailand) in the 2080s under RCP 8.5 compared to a scenario without irrigation. In addition, the grid cell that will benefit the most (12.6°N and 103.8°E) was identified through further investigation of the spatial distribution of the effects of irrigation for Cambodia. For this grid cell, the CERES-Rice model was used to develop the best combination of adaptation measures. The results show that while a doubled application rate of nitrogen fertilizer (100 kg N ha −1) will increase rice yields by 3.9% in the 2080s under the RCP 4.5 scenario for the Sen Pidao cultivar, a decrease in rice yield was projected for the Phka Rumduol cultivar under RCP 4.5. For both cultivars, the results show that additional adaptation strategies besides the 100 kg N ha −1 fertilizer application rate and planting adjustment should be applied in order to offset all of the negative projected impacts of climate change on rice yields in the 2080s under RCP 8.5. It is concluded that this study can be useful to enhance food security in Southeast Asia by providing informed recommendations for efficacious adaptation strategies.
While electrical conductivity (EC) and sodium adsorption ratio are commonly used to assess soil s... more While electrical conductivity (EC) and sodium adsorption ratio are commonly used to assess soil salinity, for detecting salinity responses during a growing season, those indicators appear to be insensitive when the soils are already high in salinity. We found that the EC and chloride concentrations in soil extracts from salt-affected greenhouses did not show a significant difference in response to different fertilizations of tomato (with a high N demand and a low susceptibility to salinity) and lettuce (the opposite) over the growing season. The fields had been treated with chemical fertilizers or chemical fertilizers plus manure composts combined with food wastes to investigate salinity enhancement by the amendments. On the other hand, the regression lines between EC and chloride concentration could show differential responses in both soil and plant extracts to the doses and salinities of fertilizers. Therefore, using the relationships between EC and associated ions can provide a better insight into the salinity susceptibilities of soils and plants.
Korean Journal of Soil Science and Fertilizer, 2021
Received: November 2, 2021 Revised: November 8, 2021 Accepted: November 8, 2021 ORCID Gwang Hyun ... more Received: November 2, 2021 Revised: November 8, 2021 Accepted: November 8, 2021 ORCID Gwang Hyun Han https://orcid.org/0000-0001-5572-7360 Chloroform fumigation and extraction (CFE) has been a widely accepted method for quantifying overall size of soil microbial community, which is a key indicator to assess the quality and health of a given soil. However, the standard procedure of CFE requires careful operations to generate enough CHCl3 vapors and flush them into soil pores. We suggest a new simple alternative for facilitating gaseous diffusion of CHCl3 molecules under ambient air pressure conditions. The microbial C values by the new approach, examined for several farmland, forest, and grassland soils, coincided well with those obtained by the standard CFE. The cell lysis and extraction coefficient was also close to that of standard CFE and much higher than that evaluated for a liquid-based CHCl3 cell lysis.
Chloride is known as the most important anion in saltaffected soils. We observed the degree of EC... more Chloride is known as the most important anion in saltaffected soils. We observed the degree of EC change upon AgCl precipitation was quantitatively related with the chloride concentration. Method validation and intercomparison with ion chromatography revealed the proposed method can provide rapid and moderately precise chloride concentrations in salt-affected soils.
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