13:45 〜 14:00
[AHW27-13] Influence of soil hydrophobicity on emissions of terrestrial greenhouse gases
★Invited Papers
キーワード：global warming, greenhouse gases, microbial decomposition, soil hydrophobicity
Over the past few decades, the planetary burden on the Earth’s atmosphere caused by a continued surge in emissions of greenhouse gases (GHGs) has become progressively evident and a serious global threat. Soil, which is known to be the largest terrestrial C sink on the earth, is susceptible to global warming and the release of GHGs from soils, intensify further warming. Next to water vapor, CO2, CH4, and N2O are the most important or the primary GHGs in Earth's atmosphere.
Soil hydrophobicity is a global phenomenon that causes soil to resist spontaneous wetting. and known to influence potentially all water-involved processes in soils. It originates through the presence of soil organic matter (SOM) with hydrophobic features, which enter the soil mainly through vegetation. Forest soils covered with conifer and other species (Ex: Cypress, Cedar, Pine, Eucalyptus, Casuarina), which are rich in hydrophobic resins and waxes, frequently exhibit hydrophobicity. The thickness of water layers, which are very crucial for microbial activities, becomes significantly thinner with increasing hydrophobicity.
The availability and the spatial distribution of water in soil matrix influences SOM decomposition and soil microbial respiration, thereby influencing the GHG emissions from soil. Reports show that hydrophobicity can decrease CO2 emission from soil, although there are contrasting influences as well. The attention focused on the relation of hydrophobicity to the emissions of CH4 and N2O from soils are lacking. Since soil hydrophobicity influences soil microbial activities, it may affect CH4 emissions from soils. Some reports claim that CH4 emission happens under both aerobic and anaerobic conditions in soil. Hydrophobicity may limit moisture-influenced microbial processes related to soil N, limiting N losses from soils. However, questions arise as to whether hydrophobicity, which is known to be undetected at near saturation, can influence anaerobic/aerobic microbial processes or not. Hydration status of pores and the diffusion pathways in the soil matrix can affect stationary microbial colonies under unsaturated conditions, resulting in reduced microbial activity. This can lead to overall low rates of organic matter decomposition and emission of GHGs from soils. The reversible nature of SOM and C makes it highly susceptible to irreversible climatic changes, potentially intensifying further warming through the release of GHGs. Understanding the relation of soil hydrophobicity to GHG emissions would provide comprehensive insight of GHG reduction in agriculture.
Soil hydrophobicity is a global phenomenon that causes soil to resist spontaneous wetting. and known to influence potentially all water-involved processes in soils. It originates through the presence of soil organic matter (SOM) with hydrophobic features, which enter the soil mainly through vegetation. Forest soils covered with conifer and other species (Ex: Cypress, Cedar, Pine, Eucalyptus, Casuarina), which are rich in hydrophobic resins and waxes, frequently exhibit hydrophobicity. The thickness of water layers, which are very crucial for microbial activities, becomes significantly thinner with increasing hydrophobicity.
The availability and the spatial distribution of water in soil matrix influences SOM decomposition and soil microbial respiration, thereby influencing the GHG emissions from soil. Reports show that hydrophobicity can decrease CO2 emission from soil, although there are contrasting influences as well. The attention focused on the relation of hydrophobicity to the emissions of CH4 and N2O from soils are lacking. Since soil hydrophobicity influences soil microbial activities, it may affect CH4 emissions from soils. Some reports claim that CH4 emission happens under both aerobic and anaerobic conditions in soil. Hydrophobicity may limit moisture-influenced microbial processes related to soil N, limiting N losses from soils. However, questions arise as to whether hydrophobicity, which is known to be undetected at near saturation, can influence anaerobic/aerobic microbial processes or not. Hydration status of pores and the diffusion pathways in the soil matrix can affect stationary microbial colonies under unsaturated conditions, resulting in reduced microbial activity. This can lead to overall low rates of organic matter decomposition and emission of GHGs from soils. The reversible nature of SOM and C makes it highly susceptible to irreversible climatic changes, potentially intensifying further warming through the release of GHGs. Understanding the relation of soil hydrophobicity to GHG emissions would provide comprehensive insight of GHG reduction in agriculture.