17:15 〜 18:30
[AHW21-P05] Climate Change Impact on Salt Affected Soil in Northeast Thailand
キーワード：土壌環境、気候変動、タイ国
In North East Thailand, annual rainfall is about 1200mm and average rice yield is only 2.1 t/ha (rain-fed). In addition, 50% of total agricultural land in this region are classified as salt affected area. Improvement of salt-affected soils in NE Thailand is a major concern of responsible agency Land Development Department(LDD) and other relevant institutions. Currently, numerous efforts have been carried out for this purpose, but existing knowledge is still insufficient. In future, climate change may cause negative impact on salt-affected soil problems. Therefore, in this study, we conducted the field survey to evaluate the seasonal changes of salt affected soil indicator such as ECe and SAR. Then, Hydrus1D was applied to predict how change the salinity level under climate change condition.
The study area was located in the salt-affected area in Ban Phai District, Khon Kaen Province, Northeast of Thailand. According to the LDD salt affected soil classification, agricultural land was classified into 4 classes including class 1 “very severely” (salt crust >50 %, ECe >16 dS/m), class 2 “severely” (salt crust 10-50%,ECe 8-16 dS/m), class 3 “moderately” (salt crust 1-10%,ECe 4-8 dS/m), and class 4 “slightly” (salt crust < 1%, ECe 2-4 dS/m). In this study, class 2 field was selected and 15 soil samples were collected in every 2 weeks from October 2016 to December 2018. Because farmers still can continue rice cultivation in class 2 field, although any crop can not grow in class 1 fields. To protect the class 2 fields is major concern for sustainable agriculture in this area. The electrical conductivity (ECe), Sodium Adsorption Ratio (SAR), soil moisture content SMC(%w/w), and soil textures were analyzed at Land Development Department Regional Office 5’s laboratory.
To predict the climate change impact, Hydrus1D model was employed in this study. Hydrus-1D is a one-dimensional finite element model for simulating the movement of water, heat, and multiple solutes in variably saturated media. The model is supported by an interactive graphics-based interface for data-preprocessing, discretization of the soil profile, and graphic presentation of the results. The soil parameters were calibrated. Calculated SMC, ECe were good agreement with observed data and SAR also simulated in sufficient. By using this Hydrus1D, future ECe and SAR were calculated by using the global circulation model (MIROC5) outputs of RCP8.5 scenario. Due to the temperature increase of 3 degree Celsius from 2006 to 2100, annual evapotranspiration increased 154 mm in 2100. And both ECe and SAR increased in the rate of 0.02dS/m/year and 0.04/year respectively. For the countermeasure, 20cm reduction of ground water level had significant effect to mitigate the salt accumulation.
The study area was located in the salt-affected area in Ban Phai District, Khon Kaen Province, Northeast of Thailand. According to the LDD salt affected soil classification, agricultural land was classified into 4 classes including class 1 “very severely” (salt crust >50 %, ECe >16 dS/m), class 2 “severely” (salt crust 10-50%,ECe 8-16 dS/m), class 3 “moderately” (salt crust 1-10%,ECe 4-8 dS/m), and class 4 “slightly” (salt crust < 1%, ECe 2-4 dS/m). In this study, class 2 field was selected and 15 soil samples were collected in every 2 weeks from October 2016 to December 2018. Because farmers still can continue rice cultivation in class 2 field, although any crop can not grow in class 1 fields. To protect the class 2 fields is major concern for sustainable agriculture in this area. The electrical conductivity (ECe), Sodium Adsorption Ratio (SAR), soil moisture content SMC(%w/w), and soil textures were analyzed at Land Development Department Regional Office 5’s laboratory.
To predict the climate change impact, Hydrus1D model was employed in this study. Hydrus-1D is a one-dimensional finite element model for simulating the movement of water, heat, and multiple solutes in variably saturated media. The model is supported by an interactive graphics-based interface for data-preprocessing, discretization of the soil profile, and graphic presentation of the results. The soil parameters were calibrated. Calculated SMC, ECe were good agreement with observed data and SAR also simulated in sufficient. By using this Hydrus1D, future ECe and SAR were calculated by using the global circulation model (MIROC5) outputs of RCP8.5 scenario. Due to the temperature increase of 3 degree Celsius from 2006 to 2100, annual evapotranspiration increased 154 mm in 2100. And both ECe and SAR increased in the rate of 0.02dS/m/year and 0.04/year respectively. For the countermeasure, 20cm reduction of ground water level had significant effect to mitigate the salt accumulation.