The agriculture in Biskra,southeastern Algeria,is based on traditional practices and characterized by small irrigated fields.In the last decades,the increasing demand in water as well as the scarcity of rainfall has f...The agriculture in Biskra,southeastern Algeria,is based on traditional practices and characterized by small irrigated fields.In the last decades,the increasing demand in water as well as the scarcity of rainfall has forced many farmers to use groundwater of low quality to maintain the profitability of their crops.Unfortunately,this practice seems to be the main harmful factor for soil quality in the region since it is responsible for the salinization of the irrigated areas.Aiming to assess the impact of this phenomenon,the soils of the irrigated perimeter of El Ghrous-a representative rural community located in the west of Biskra-have been analyzed.A set of 82 soil samples was collected from top and subsoil(0-15 and15-35 cm respectively),on which the following physicochemical analyzes were performed:Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),SO_(4)^(2-),HCO_(3)^(-),NO_(3)^(-),pH,electrical conductivity(EC)and sodium adsorption ratio.A Principal Component Analysis was performed to individuate the geochemical processes that influenced significantly the evolution of soil salinity and its pathways.The results showed a calcium sulfate(CaSO_(4))facies with a high risk of salinity and a low to medium risk of alkalinity.The calcite residual alkalinity and generalized residual alkalinity decreased as the solutions became more concentrated.Most of the samples were oversaturated in carbonate minerals(aragonite,calcite,and dolomite)and under saturated in evaporitic minerals(anhydrite,gypsum,and halite).Finally,two multiple linear regressions(using cations and anions as independent variables)have been proposed to quantify soil salinity.These equations,with an accuracy of 85%,can represent a time and money-saving tool for managers and farmers to estimate the EC,in comparison to the traditional estimation methods.展开更多
Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions,which makes it necessary to establish an efficient strategy to manage soil salinity and co...Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions,which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it.Saline soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty soil.To develop suitable management strategies for salty soil reclamation,it is essential to improve soil salinity assessment pro cess/mechanism and to adopt new approaches and techniques.T his study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in K airouan region in Central Tunisia,taking into account the thickness of soil materials.Two electromagnetic conductivity meters(EM38 and EM31)were used to measure the electrical conductivity of saturated soil-paste extract(ECe)and apparent electrical conductivity(E Ca).Multiple linear regression was established between ECe and ECa,and it was revealed that ECa-EM38 is optimal for E Ce prediction in the surface soils.Salinity maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied temporally.Variation in salinity at the soil surface was greater than that at a depth.These findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity,thus improving the efficiency of soil management.展开更多
Electrical conductivity(EC)of soil-water extracts is commonly used to assess soil salinity.However,its conversion to the EC of saturated soil paste extracts(ECe),the standard measure of soil salinity,is currently requ...Electrical conductivity(EC)of soil-water extracts is commonly used to assess soil salinity.However,its conversion to the EC of saturated soil paste extracts(ECe),the standard measure of soil salinity,is currently required for practical applications.Although many regression models can be used to obtain ECe from the EC of soil-water extracts,the application of a site-specific model to different sites is not straightforward due to confounding soil factors such as soil texture.This study was conducted to develop a universal regression model to estimate a conversion factor(CF)for predicting EC_(e) from EC of soil-water extracts at a 1:5 ratio(EC_(1:5)),by employing a site-specific soil texture(i.e.,sand content).A regression model,CF=8.9105e^(0.0106sand)/1.2984(r^(2)=0.97,P<0.001),was developed based on the results of coastal saline soil surveys(n=173)and laboratory experiments using artificial saline soils with different textures(n=6,sand content=10%-65%)and salinity levels(n=7,salinity=1-24 dS m^(-1)).Model performance was validated using an independent dataset and demonstrated that EC_(e) prediction using the developed model is more suitable for highly saline soils than for low saline soils.The feasibility of the regression model should be tested at other sites.Other soil factors affecting EC conversion factor also need to be explored to revise and improve the model through further studies.展开更多
为了探究测定时间对定水头法土壤饱和导水率(Saturated soil hydraulic conductivity,Ks)测定结果的影响,采用室内模拟试验,以关中塿土为研究对象,测定原状土(1.5 g cm-3)及不同容重(1.2、1.3、1.4、1.5、1.6 g cm-3)扰动土长时间序列下...为了探究测定时间对定水头法土壤饱和导水率(Saturated soil hydraulic conductivity,Ks)测定结果的影响,采用室内模拟试验,以关中塿土为研究对象,测定原状土(1.5 g cm-3)及不同容重(1.2、1.3、1.4、1.5、1.6 g cm-3)扰动土长时间序列下(45 d)的饱和导水率及出流液电导率,并在实验结束后将土样分层用吸管法测定颗粒组成。结果表明:饱和导水率测定值随时间先迅速降低达到一个拐点(近稳定点)后缓慢降低至最终稳定,对于原状塿土,近稳定点(1.33 d)Ks测定值0.0762 cm h-1与终稳定点(4.42 d)Ks值0.0640 cm h-1差异不显著(P>0.05),初步建议测定时间为1.5 d。原状土比同容重的扰动土先达到稳定且稳定时的Ks值更大,随着土壤容重增加,Ks越快稳定(分别4.92、4.42、2.92、2.5、1.5 d),且稳定时Ks值越小。不同时刻出流液的电导率与饱和导水率极显著相关(P<0.01),试验后粉粒含量随土样深度有所上升,说明土粒的膨胀与迁移对Ks测定的稳定时间均有影响。展开更多
文摘The agriculture in Biskra,southeastern Algeria,is based on traditional practices and characterized by small irrigated fields.In the last decades,the increasing demand in water as well as the scarcity of rainfall has forced many farmers to use groundwater of low quality to maintain the profitability of their crops.Unfortunately,this practice seems to be the main harmful factor for soil quality in the region since it is responsible for the salinization of the irrigated areas.Aiming to assess the impact of this phenomenon,the soils of the irrigated perimeter of El Ghrous-a representative rural community located in the west of Biskra-have been analyzed.A set of 82 soil samples was collected from top and subsoil(0-15 and15-35 cm respectively),on which the following physicochemical analyzes were performed:Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),SO_(4)^(2-),HCO_(3)^(-),NO_(3)^(-),pH,electrical conductivity(EC)and sodium adsorption ratio.A Principal Component Analysis was performed to individuate the geochemical processes that influenced significantly the evolution of soil salinity and its pathways.The results showed a calcium sulfate(CaSO_(4))facies with a high risk of salinity and a low to medium risk of alkalinity.The calcite residual alkalinity and generalized residual alkalinity decreased as the solutions became more concentrated.Most of the samples were oversaturated in carbonate minerals(aragonite,calcite,and dolomite)and under saturated in evaporitic minerals(anhydrite,gypsum,and halite).Finally,two multiple linear regressions(using cations and anions as independent variables)have been proposed to quantify soil salinity.These equations,with an accuracy of 85%,can represent a time and money-saving tool for managers and farmers to estimate the EC,in comparison to the traditional estimation methods.
文摘Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions,which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it.Saline soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty soil.To develop suitable management strategies for salty soil reclamation,it is essential to improve soil salinity assessment pro cess/mechanism and to adopt new approaches and techniques.T his study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in K airouan region in Central Tunisia,taking into account the thickness of soil materials.Two electromagnetic conductivity meters(EM38 and EM31)were used to measure the electrical conductivity of saturated soil-paste extract(ECe)and apparent electrical conductivity(E Ca).Multiple linear regression was established between ECe and ECa,and it was revealed that ECa-EM38 is optimal for E Ce prediction in the surface soils.Salinity maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied temporally.Variation in salinity at the soil surface was greater than that at a depth.These findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity,thus improving the efficiency of soil management.
基金support of the Cooperative Research Program of Agriculture Science and Technology Development,Rural Development Administration,Republic of Korea(No.PJ0138732021)。
文摘Electrical conductivity(EC)of soil-water extracts is commonly used to assess soil salinity.However,its conversion to the EC of saturated soil paste extracts(ECe),the standard measure of soil salinity,is currently required for practical applications.Although many regression models can be used to obtain ECe from the EC of soil-water extracts,the application of a site-specific model to different sites is not straightforward due to confounding soil factors such as soil texture.This study was conducted to develop a universal regression model to estimate a conversion factor(CF)for predicting EC_(e) from EC of soil-water extracts at a 1:5 ratio(EC_(1:5)),by employing a site-specific soil texture(i.e.,sand content).A regression model,CF=8.9105e^(0.0106sand)/1.2984(r^(2)=0.97,P<0.001),was developed based on the results of coastal saline soil surveys(n=173)and laboratory experiments using artificial saline soils with different textures(n=6,sand content=10%-65%)and salinity levels(n=7,salinity=1-24 dS m^(-1)).Model performance was validated using an independent dataset and demonstrated that EC_(e) prediction using the developed model is more suitable for highly saline soils than for low saline soils.The feasibility of the regression model should be tested at other sites.Other soil factors affecting EC conversion factor also need to be explored to revise and improve the model through further studies.
文摘为了探究测定时间对定水头法土壤饱和导水率(Saturated soil hydraulic conductivity,Ks)测定结果的影响,采用室内模拟试验,以关中塿土为研究对象,测定原状土(1.5 g cm-3)及不同容重(1.2、1.3、1.4、1.5、1.6 g cm-3)扰动土长时间序列下(45 d)的饱和导水率及出流液电导率,并在实验结束后将土样分层用吸管法测定颗粒组成。结果表明:饱和导水率测定值随时间先迅速降低达到一个拐点(近稳定点)后缓慢降低至最终稳定,对于原状塿土,近稳定点(1.33 d)Ks测定值0.0762 cm h-1与终稳定点(4.42 d)Ks值0.0640 cm h-1差异不显著(P>0.05),初步建议测定时间为1.5 d。原状土比同容重的扰动土先达到稳定且稳定时的Ks值更大,随着土壤容重增加,Ks越快稳定(分别4.92、4.42、2.92、2.5、1.5 d),且稳定时Ks值越小。不同时刻出流液的电导率与饱和导水率极显著相关(P<0.01),试验后粉粒含量随土样深度有所上升,说明土粒的膨胀与迁移对Ks测定的稳定时间均有影响。
