Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropi...Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropical and temperate regions represent different physical behaviors,and the quantification of their physical properties is important to support soil evaluation and modelling.The objective of this study was to evaluate the SPQ in a subtropical field under maize crop cultivation according to its physical properties,hydraulic indices,and functions in an attempt to infer the spatial variability and to determine the behavior of soil physical structure across a spatial domain.Commonly used soil key physical variables,such as texture,bulk density,total porosity,saturated hydraulic conductivity,and organic carbon content,were measured in a regular grid with a soil sampling density of 30 points per hectare,covering an area of0.5 ha.Saturated hydraulic conductivity varied strongly between subsamples and in the field,suggesting the heterogeneity of the soil structure regarding water drainage.The physical variables were combined with other indicators,which were based on the soil water retention curve and the pore size distribution(PSD)function.Correlation analysis was performed to verify the relationship between the measured and calculated variables,and some strong linear correlations were revealed,such as between aeration energy index and microporosity(r=0.608)and water retention energy index with microporosity(r=0.532)and with bulk density(r=0.541).For most sampled locations,the shape and location parameters of PSD showed results outside of the optimum ranges,whereas the hydraulic energy indices and cumulative hydraulic energy functions presented values that were similar to those found for some tropical soils described in the literature.The spatial variability of these indices was described using semivariograms and kriged maps,indicating the variability of the SPQ in this field.展开更多
The saturated hydraulic conductivity(K_(s))and water retention curve(SWRC)parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world.Therefore,...The saturated hydraulic conductivity(K_(s))and water retention curve(SWRC)parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world.Therefore,K_(s) and SWRC are related with the soil physical quality(SPQ)and several SPQ indices can be derived from SWRC,such as the pore size distribution,relative field capacity,plant available water,drainable porosity,and soil hydraulic-energy indices(SHEI).It is well known that the soil structure can be assessed by using SHEI,but a possible physical relationship between K_(s) and SHEI was not examined yet.Therefore,the objective of this study was to investigate the behavior of K_(s) as function of SHEI for several soil textural classes.If this relationship be proved,then SHEI might be applied to improve the K_(s) prediction by PTF models.In this work,a data set of 395 measured SWRC's were fitted to the vG equation to obtain the SHEI to verify whether they are statistically correlated and physically dependent on K_(s).The resulting parametric and non-parametric correlation results were split up according to six textural classes.The significant influence of K_(s) on at least one of the absolute SHEI(A_(a) or WR_(a))was verified on the numerical scale when all textures were grouped and on numerical and pF scales for clayey and silty textures.K_(s) showed significant impact on A_(a) and WR_(a) indices in four textural classes.Furthermore,K_(s) had influence on the sum A_(a)þWR_(a) denoted in pF scale for five of the six textural classes,with a significant linear correlation in the clayey texture when log(A_(a)+WR_(a))was applied.The significant and high correlation of K_(s) on the ratios WR_(a)/AWC and A_(a)/4D was also observed in four of the six classes,and therefore the use of these indices is recommended for the development of PTFs for K_(s) prediction.展开更多
基金financed in part by the Coordination of Improvement of Higher Education Personnel(CAPES),Brazil(No.001)。
文摘Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropical and temperate regions represent different physical behaviors,and the quantification of their physical properties is important to support soil evaluation and modelling.The objective of this study was to evaluate the SPQ in a subtropical field under maize crop cultivation according to its physical properties,hydraulic indices,and functions in an attempt to infer the spatial variability and to determine the behavior of soil physical structure across a spatial domain.Commonly used soil key physical variables,such as texture,bulk density,total porosity,saturated hydraulic conductivity,and organic carbon content,were measured in a regular grid with a soil sampling density of 30 points per hectare,covering an area of0.5 ha.Saturated hydraulic conductivity varied strongly between subsamples and in the field,suggesting the heterogeneity of the soil structure regarding water drainage.The physical variables were combined with other indicators,which were based on the soil water retention curve and the pore size distribution(PSD)function.Correlation analysis was performed to verify the relationship between the measured and calculated variables,and some strong linear correlations were revealed,such as between aeration energy index and microporosity(r=0.608)and water retention energy index with microporosity(r=0.532)and with bulk density(r=0.541).For most sampled locations,the shape and location parameters of PSD showed results outside of the optimum ranges,whereas the hydraulic energy indices and cumulative hydraulic energy functions presented values that were similar to those found for some tropical soils described in the literature.The spatial variability of these indices was described using semivariograms and kriged maps,indicating the variability of the SPQ in this field.
基金support through the Multistate Project KY006120“Soil,Water,and Environmental Physics to Sustain Agriculture and Natural Resources”from the University of Kentucky Agricultural Experiment Station.
文摘The saturated hydraulic conductivity(K_(s))and water retention curve(SWRC)parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world.Therefore,K_(s) and SWRC are related with the soil physical quality(SPQ)and several SPQ indices can be derived from SWRC,such as the pore size distribution,relative field capacity,plant available water,drainable porosity,and soil hydraulic-energy indices(SHEI).It is well known that the soil structure can be assessed by using SHEI,but a possible physical relationship between K_(s) and SHEI was not examined yet.Therefore,the objective of this study was to investigate the behavior of K_(s) as function of SHEI for several soil textural classes.If this relationship be proved,then SHEI might be applied to improve the K_(s) prediction by PTF models.In this work,a data set of 395 measured SWRC's were fitted to the vG equation to obtain the SHEI to verify whether they are statistically correlated and physically dependent on K_(s).The resulting parametric and non-parametric correlation results were split up according to six textural classes.The significant influence of K_(s) on at least one of the absolute SHEI(A_(a) or WR_(a))was verified on the numerical scale when all textures were grouped and on numerical and pF scales for clayey and silty textures.K_(s) showed significant impact on A_(a) and WR_(a) indices in four textural classes.Furthermore,K_(s) had influence on the sum A_(a)þWR_(a) denoted in pF scale for five of the six textural classes,with a significant linear correlation in the clayey texture when log(A_(a)+WR_(a))was applied.The significant and high correlation of K_(s) on the ratios WR_(a)/AWC and A_(a)/4D was also observed in four of the six classes,and therefore the use of these indices is recommended for the development of PTFs for K_(s) prediction.
