The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio ...The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.展开更多
Soil salinization may negatively affect microbial processes related to carbon dioxide （CO2） and nitrous oxide （N20） emissions. A short-term laboratory incubation experiment was conducted to investigate the effects...Soil salinization may negatively affect microbial processes related to carbon dioxide （CO2） and nitrous oxide （N20） emissions. A short-term laboratory incubation experiment was conducted to investigate the effects of soil electrical conductivity （EC） and moisture content on CO2 and N20 emissions from sulfate-based natural saline soils. Three separate 100-m long transects were established along the salinity gradient on a salt-affected agricultural field at Mooreton, North Dakota, USA. Surface soils were collected from four equally spaced sampling positions within each transect, at the depths of 0-15 and 15-30 cm. In the laboratory, artificial soil cores were formed combining soils from both the depths in each transect, and incubated at 60% and 90% water-filled pore space （WFPS） at 25 ~C. The measured depth-weighted EC of the saturated paste extract （ECe） across the sampling positions ranged from 0.43 to 4.65 dS m-1. Potential nitrogen （N） mineralization rate and CO2 emissions decreased with increasing soil ECe, but the relative decline in soil CO2 emissions with increasing ECe was smaller at 60% WFPS than at 90% WFPS. At 60% WFPS, soil N20 emissions decreased from 133 g N20-N kg-1 soil at ECe （ 0.50 dS m-1 to 72 μg N20-N kg-1 soil at ECe = 4.65 dS m-1. In contrast, at 90% WFPS, soil N20 emissions increased from 262 g N20-N kg-1 soil at ECe ： 0.81 dS m-1 to 849 g N20-N kg-1 soil at ECe ： 4.65 dS m-1, suggesting that N20 emissions were linked to both soil ECe and moisture content. Therefore, spatial variability in soil ECe and pattern of rainfall over the season need to be considered when up-scaling N20 and CO2 emissions from field to landscape scales.展开更多
Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River....Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River. The saline soil and groundwater depth data of the county in 1981 were obtained to serve as a historical reference. Electrical conductivity （EC） of 293 surface soil samples taken from 2 kin x 2 km grids in 2007 and 4{） soil profiles acquired in 2（108 was analyzed and used for comparative mapping. Ordinary kriging was applied to predict EC at unobserved locations to derive the horizontal and vertical distribution patterns and variation of soil salinity. Groundwater table data from 22 observation wells in 2008 were collected and used as input for regression kriging to predict the maximum groundwater depth of the county in 2008. Changes in the groundwater level of Fengqiu County in 27 years from 1981 to 2008 was calculated. Two quantitative criteria, the mean error or bias （ME） and the mean squared error （MSE）, were computed to assess the estimation accuracy of the kriging predictions. The results demonstrated that the soil salinity in the upper soil layers decreased dramatically and the taxonomically defined saline soils were present only in a few micro-landscapes after 27 years. Presently, the soils with relatively elevated salt content were mainly distributed in depressions along the Yellow River bed. The reduction in surface soil salinity corresponded to the locations with deepened maximum groundwater depth. It could be concluded that groundwater table recession allowed water to move deeper into the soil profile, transporting salts with it, and thus played an important role in reducing soil salinity in this region. Accumulation of salts in the soil profiles at various depths below the surface indicated that secondary soil salinization would occur when the groundwater was not controlled at a safe depth.展开更多
基金Sponsored by the Major State Scientific and Technological Projects of Water Pollution Control and Treatment(Grant No.2008ZX07208-005)
文摘The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.
文摘Soil salinization may negatively affect microbial processes related to carbon dioxide （CO2） and nitrous oxide （N20） emissions. A short-term laboratory incubation experiment was conducted to investigate the effects of soil electrical conductivity （EC） and moisture content on CO2 and N20 emissions from sulfate-based natural saline soils. Three separate 100-m long transects were established along the salinity gradient on a salt-affected agricultural field at Mooreton, North Dakota, USA. Surface soils were collected from four equally spaced sampling positions within each transect, at the depths of 0-15 and 15-30 cm. In the laboratory, artificial soil cores were formed combining soils from both the depths in each transect, and incubated at 60% and 90% water-filled pore space （WFPS） at 25 ~C. The measured depth-weighted EC of the saturated paste extract （ECe） across the sampling positions ranged from 0.43 to 4.65 dS m-1. Potential nitrogen （N） mineralization rate and CO2 emissions decreased with increasing soil ECe, but the relative decline in soil CO2 emissions with increasing ECe was smaller at 60% WFPS than at 90% WFPS. At 60% WFPS, soil N20 emissions decreased from 133 g N20-N kg-1 soil at ECe （ 0.50 dS m-1 to 72 μg N20-N kg-1 soil at ECe = 4.65 dS m-1. In contrast, at 90% WFPS, soil N20 emissions increased from 262 g N20-N kg-1 soil at ECe ： 0.81 dS m-1 to 849 g N20-N kg-1 soil at ECe ： 4.65 dS m-1, suggesting that N20 emissions were linked to both soil ECe and moisture content. Therefore, spatial variability in soil ECe and pattern of rainfall over the season need to be considered when up-scaling N20 and CO2 emissions from field to landscape scales.
基金Supported by the Innovation and Cutting-Edge Project of the Institute of Soil Science, Chinese Academy of Sciences (No. ISSASIP0716)the National Natural Science Foundation of China (No. 40701070)the Knowledge Innovation Project of the Chinese Academy of Sciences (No. KSCX1-YW-09-02)
文摘Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River. The saline soil and groundwater depth data of the county in 1981 were obtained to serve as a historical reference. Electrical conductivity （EC） of 293 surface soil samples taken from 2 kin x 2 km grids in 2007 and 4{） soil profiles acquired in 2（108 was analyzed and used for comparative mapping. Ordinary kriging was applied to predict EC at unobserved locations to derive the horizontal and vertical distribution patterns and variation of soil salinity. Groundwater table data from 22 observation wells in 2008 were collected and used as input for regression kriging to predict the maximum groundwater depth of the county in 2008. Changes in the groundwater level of Fengqiu County in 27 years from 1981 to 2008 was calculated. Two quantitative criteria, the mean error or bias （ME） and the mean squared error （MSE）, were computed to assess the estimation accuracy of the kriging predictions. The results demonstrated that the soil salinity in the upper soil layers decreased dramatically and the taxonomically defined saline soils were present only in a few micro-landscapes after 27 years. Presently, the soils with relatively elevated salt content were mainly distributed in depressions along the Yellow River bed. The reduction in surface soil salinity corresponded to the locations with deepened maximum groundwater depth. It could be concluded that groundwater table recession allowed water to move deeper into the soil profile, transporting salts with it, and thus played an important role in reducing soil salinity in this region. Accumulation of salts in the soil profiles at various depths below the surface indicated that secondary soil salinization would occur when the groundwater was not controlled at a safe depth.
