With the increased interest of plants in space, gravity cannot be ignored when studying soil-plant-water relations. Therefore, it is important to understand the water relations of soils under zero gravity in space or ...With the increased interest of plants in space, gravity cannot be ignored when studying soil-plant-water relations. Therefore, it is important to understand the water relations of soils under zero gravity in space or under reduced gravity on the Moon or Mars. This paper outlines the problems of moving water in soils under zero gravity or microgravity, as well as growing plants in these soils. It is suggested that microgravity experiments could be done on Earth using both soils and plants. Results from such experiments could be used to grow plants when mankind establishes bases on the Moon and Mars.展开更多
The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not...The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not feasible using existing soil-erosion models.This study measured the site-specific concentrations of ^(137)Cs and ^(210)Pb_(ex) on both a highland slope(33%slope)and a reference site(undisturbed flat area)to estimate soil erosion and redistribution.The use of the fallout radionuclide(FRN)method was evaluated to see if it is a suitable method for characterizing soil erosion.Results were compared with those obtained with the Universal Soil Loss Equation(USLE),which is an empirical model that estimates annual soil erosion.The average concentrations of ^(137)Cs and ^(210)Pb_(ex) at the reference site were 11.57±0.24 Bq kg^(-1) and 59.74±4.2 Bq kg^(-1),respectively.Concentrations of ^(137)Cs and ^(210)Pb_(ex) in the experimental slope were 16.4%and 10.8%,respectively,of those at the reference site.Radionuclide inventories were lower at the upper point of the slope than those at the basal point of the slope.Concentrations of ^(137)Cs and ^(210)Pb_(ex) were significantly correlated with available phosphorus,organic matter,CEC,and exchangeable cations.Estimation of soil redistribution rate using ^(137)Cs and ^(210)Pb_(ex) showed site-specific variations at different points along the slope,and respective ranges were^(-1)7.46~-207.51 and 1.55~-581.38 Mgha^(-1) yr^(-1),which indicated that more erosion was assessed by ^(210)Pb_(ex) than by ^(137)Cs.Redistribution analysis showed that soil erosion occurred along the entire slope,except for the bottom point of the slope where 1.55 Mgha^(-1) yr^(-1) of sediment accumulated.The USLE provided a single value of the average annual soil loss in the entire slope,which was either 166 or 398 Mgha^(-1) yr^(-1),depending on the soil erodibility factor(soil series factor and calculated factor from soil sample analysis)used in the model.We conclude that the FRN method using ^(137)Cs and ^(210)Pb_(ex) radionuclides can be used to assess soil erosion and redistribution in steeply sloping agricultural highlands.Verification of soil-erosion values using the FRN method and soil-erosion models has been controversial,but it merits further study at many locations with different soils,topography,and management practices.展开更多
文摘With the increased interest of plants in space, gravity cannot be ignored when studying soil-plant-water relations. Therefore, it is important to understand the water relations of soils under zero gravity in space or under reduced gravity on the Moon or Mars. This paper outlines the problems of moving water in soils under zero gravity or microgravity, as well as growing plants in these soils. It is suggested that microgravity experiments could be done on Earth using both soils and plants. Results from such experiments could be used to grow plants when mankind establishes bases on the Moon and Mars.
基金This research was supported in part by Research Grant from Kangwon National University(No.520160156:2016)the Korea Ministry of Environment,with the strategic EcoSSSoil Project,KEITI(Korea Environmental Industry and Technology Institute),Korea(Grant No.2019002820004).
文摘The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not feasible using existing soil-erosion models.This study measured the site-specific concentrations of ^(137)Cs and ^(210)Pb_(ex) on both a highland slope(33%slope)and a reference site(undisturbed flat area)to estimate soil erosion and redistribution.The use of the fallout radionuclide(FRN)method was evaluated to see if it is a suitable method for characterizing soil erosion.Results were compared with those obtained with the Universal Soil Loss Equation(USLE),which is an empirical model that estimates annual soil erosion.The average concentrations of ^(137)Cs and ^(210)Pb_(ex) at the reference site were 11.57±0.24 Bq kg^(-1) and 59.74±4.2 Bq kg^(-1),respectively.Concentrations of ^(137)Cs and ^(210)Pb_(ex) in the experimental slope were 16.4%and 10.8%,respectively,of those at the reference site.Radionuclide inventories were lower at the upper point of the slope than those at the basal point of the slope.Concentrations of ^(137)Cs and ^(210)Pb_(ex) were significantly correlated with available phosphorus,organic matter,CEC,and exchangeable cations.Estimation of soil redistribution rate using ^(137)Cs and ^(210)Pb_(ex) showed site-specific variations at different points along the slope,and respective ranges were^(-1)7.46~-207.51 and 1.55~-581.38 Mgha^(-1) yr^(-1),which indicated that more erosion was assessed by ^(210)Pb_(ex) than by ^(137)Cs.Redistribution analysis showed that soil erosion occurred along the entire slope,except for the bottom point of the slope where 1.55 Mgha^(-1) yr^(-1) of sediment accumulated.The USLE provided a single value of the average annual soil loss in the entire slope,which was either 166 or 398 Mgha^(-1) yr^(-1),depending on the soil erodibility factor(soil series factor and calculated factor from soil sample analysis)used in the model.We conclude that the FRN method using ^(137)Cs and ^(210)Pb_(ex) radionuclides can be used to assess soil erosion and redistribution in steeply sloping agricultural highlands.Verification of soil-erosion values using the FRN method and soil-erosion models has been controversial,but it merits further study at many locations with different soils,topography,and management practices.
