Soil Moisture Characteristic Curve Research Articles

Consideration of Vadose Zone Moisture Dynamics in Remediation of PFAS‐Impacted Soils

AbstractOilfield brines are soluble, non‐volatile, and recalcitrant contaminants that are vulnerable to capillary effects and evapoconcentration and have been known to recontaminate clean fill soils emplaced after excavations. This problem may also occur for some poly‐ and perfluoroalkyl substances (PFAS) at PFAS sites. In this paper, we consider the soil moisture characteristic curve, wetting front dynamics, and the moisture redistribution cycle to understand the potential behavior of different PFAS in the vadose zone. Drawing on experience with remediation of soils impacted by brine spills, we provide recommendations on the design and implementation of soil excavation and cover remedies such as capillary barriers to prevent recontamination.

Soil-Matric-Potential-Based Irrigation Scheduling to Increase Yield and Water Productivity of Okra

A field experiment was conducted on okra (Abelmoschus esculentus L.) for assessing the sustainability of yield with optimum irrigation schedule based on soil moisture depletion. Four irrigation treatments: Irrigation at I1:20%, I2:30%, I3:40% and I4:50% of soil moisture depletion rate in main plots and three fertilizer treatments: Fertigation at F1:100%, F2:80% and F3:60% of recommended NPK (100:25:40 kg/ha) in subplots were tested. Soil matric potential was recorded continuously using electronic tensiometers. The soil moisture characteristics curve was derived for various soil matric potential value sand the soil water content. The irrigation controller triggered solenoid valves for irrigation when soil moisture depletion reached a prespecified level in each treatment. Soil moisture depletion values were significantly predicted based on a regression model calibrated for each treatment over the crop growing period. The model gave minimum prediction error (PE) for I1, followed by I2, I3 and I4, respectively. Plant growth and yield parameters were significantly influenced by the soil moisture availability under each treatment. It is recommended that irrigation be scheduled at 20% soil moisture depletion rate together with 100% NPK fertilizer application for attaining sustainable yield of okra (12.3 t/ha), apart from maximum WUE (3.5 kg/m3) and plant growth parameters under semiarid inceptisols.

Assessing the effects of agricultural waste returning on soil moisture characteristics

AbstractAgricultural waste is an emerging and promising resource due to its abundant organic compounds and high water‐holding capacity. It plays a crucial role in improving soil water use efficiency and contributing to sustainable agricultural development. This study aimed to investigate the impact of returning agricultural waste on soil moisture characteristics. Different volume ratios (4:5:1:0, 3:5:1:1, 2:5:1:2, 1:5:1:3, and 0:5:1:4) of agricultural waste blend (AWB) consisting of cattle manure, yellow loam soil, wheat straw, and distiller's grains were examined, and the water‐holding performance of the five AWB ratios under various suction forces was compared. The analysis confirmed the suitability of the Van Genuchten‐Mualem model for fitting soil moisture characteristic curves at different ratios. The study also examined the influences of AWB ratios on soil‐specific water capacity, hydraulic parameters, and equivalent pore size. The results showed that agricultural waste effectively increased soil‐specific water capacity, available water content, soil WHC(Water‐holding capacity), and soil pore count. Furthermore, reducing cattle manure and increasing distiller's grains enhanced these effects. For instance, when the AWB ratio was 0:5:1:4, soil‐specific water capacity increased by 47.7%, while field WHC and available water content increased by 9.9% and 3.8%, respectively. Additionally, the number of extremely small and small pores increased by 1.4% and 0.77%, respectively. These findings provide valuable theoretical guidance for agricultural waste treatment and improving soil WHC. Based on the results, it is recommended to increase the proportion of distiller's grains and reduce organic fertilizer when using agricultural waste for improving soil WHC.

Mechanical Analysis of Road Graben Slopes Based on Saturated-Unsaturated Seepage Theory

As the construction of mountainous highways continues to heat up, the stability analysis of road graben slopes becomes one of the current research hotspots. In this paper, based on the saturated-unsaturated seepage theory, the force analysis of the road graben slope under rainfall conditions and its laws are studied. Firstly, the damage mode of the road graben slope and its three damage stages of creeping deformation, sliding damage and tendency to stability are summarized according to the engineering practice and literature survey, and the right side of the road graben slope from K316+439 to K316+859 of Longlian Expressway is monitored, so as to amend the next theoretical analysis. The three stages of rainfall infiltration were analyzed, the state variables and material variables of soil water were selected according to the continuous medium theory and the soil water suction analysis was carried out. Based on the saturated-unsaturated seepage theory, the fluid-structure interaction mathematical model and soil moisture characteristic curve (SWCC) model under rainfall infiltration conditions were established, and the stress of the cutting slope under saturation conditions was analyzed. The experimental results show that for the soil at the foot of the slope, the infiltration depth of rainfall is limited due to the low permeability coefficient, and the change of seepage field is not obvious; the longer the rainfall is held, the deeper the infiltration depth is, and the rainfall will continuously replenish the groundwater, so the force on the slope of the road graben will increase continuously and finally reach the limit of damage. When the rainfall intensity is 5mm-h-1, the decline of stability coefficient for 48 h is 0.121; the initial stability coefficient of the slope is the largest when the dip angle of the weak interlayer is equal to 25∘, and the stability coefficient decreases rapidly with the rainfall time, and when the rainfall reaches 60 h, the stability coefficient tends to be stable and the equilibrium of the slope force no longer changes.

Simultaneous enhancement of soil properties along with water-holding and restriction of Pb–Cd mobility in a soil-plant system by the addition of a phosphorus-modified biochar to the soil

Soil quality deterioration and heavy metal contamination have greatly limited soil productivity in mining areas. As soil is a complex system with various properties and interactions, it is imperative to conduct a comprehensive investigation to understand the amendment's mechanisms at work in the soil in mining areas as well as effective ways to address its deteriorating quality. In this study, a potassium dihydrogen phosphate-modified maize straw-cow dung biochar (PBC) was applied as a soil amendment. Various physicochemical properties of the soil including organic matter, total nitrogen, available phosphorus, and pore characteristics were analyzed. This study also assessed soil-saturated water content and soil moisture characteristic curve. Lettuce biomass was measured and changes in various speciation of Pb and Cd in the soil, and the accumulation of Pb and Cd in lettuce were examined. Results showed that the addition of PBC increased soil organic matter, total nitrogen, and available phosphorus while reducing soil bulk density, it also increased soil porosity, saturated water content, and capillary water capacity. Soil structure analysis using CT scanning revealed that 3% PBC increased the macrospores volume fraction while 5% PBC made the pores more uniform. Lettuce biomass increased by 53.3%. 5% PBC resulted in a 56.79% and 38.30% reduction in Pb and a 44.56% and 16.60% reduction in Cd in roots and shoots of lettuce respectively. PBC facilitated the transformation of Pb and Cd from unstable fractions to stable fractions through complexation and precipitation. Overall, the addition of PBC effectively improved soil nutrients, porosity, and water-holding capacity, promoted plant growth, immobilized Pb and Cd, as well as reduced the bioavailability in contaminated-soil from mining areas. This study provides an effective strategy and a new perspective for the remediation of Pb–Cd-contaminated soils.

Effects of five years conservation tillage for hedging against drought, stabilizing maize yield, and improving soil environment in the drylands of northern China.

Continuous tillage cultivation positioning trials can provide the basis for maintaining soil health, improving resource utilization efficiency and crop productivity, and achieving sustainable agricultural development. In this study, changes in soil stability and water-holding capacity characteristics were measured under different tillage cultivations from a multi-year microscopic perspective and analyzed to evaluate selected key indicators. Continuous monitoring of rainfall utilization efficiency and yield was carried out for five years. Here, we discuss the role of conservation tillage in buffering and stabilizing rainfall precipitation pattern on the fluctuation and uncertainty of soil water retention and water supply capacity and soil quality. The study was carried out on dryland areas of the Loess Plateau in northern China with eight tillage systems established in 2016: no-tillage (NT); no-tillage and straw (NTS); subsoiling (SU); subsoiling and straw (SUS); rotary tillage (RT); rotary tillage and straw (RTS); conventional tillage (CT); and conventional tillage and straw (CTS). All treatments were applied in conjunction with continuous cropping for five years. The evaluated soil parameters were mean weight diameter (MWD), geometric mean diameter (GMD), >0.25 mm aggregate content (R0.25) of water-stable aggregates (WSAs), soil moisture characteristic curve (SMCC), specific soil water capacity (Cθ), soil organic matter (SOM), rainfall utilization efficiency (RUE), and maize yields for five consecutive years. The MWD, GMD, and R0.25 of SUS were 27.38%, 17.57%, and 7.68% more than CTS (control), respectively. Overall, SOM, average annual RUE, and average annual yields increased by 14.64%, 11.89%, and 9.59%, respectively, compared with 2016. Our results strongly suggest that conservation tillage can considerably improve these characterization indicators. SUS was more effective than CTS in the 0-40 cm soil layer at hedging against drought in the area, stabilizing crop production, and achieving sustainable agricultural development.

The ecosystem wilting point defines drought response and recovery of a Quercus-Carya forest.

Soil and atmospheric droughts increasingly threaten plant survival and productivity around the world. Yet, conceptual gaps constrain our ability to predict ecosystem-scale drought impacts under climate change. Here, we introduce the ecosystem wilting point (ΨEWP ), a property that integrates the drought response of an ecosystem's plant community across the soil-plant-atmosphere continuum. Specifically, ΨEWP defines a threshold below which the capacity of the root system to extract soil water and the ability of the leaves to maintain stomatal function are strongly diminished. We combined ecosystem flux and leaf water potential measurements to derive the ΨEWP of a Quercus-Carya forest from an "ecosystem pressure-volume (PV) curve," which is analogous to the tissue-level technique. When community predawn leaf water potential (Ψpd ) was above ΨEWP (=-2.0MPa), the forest was highly responsive to environmental dynamics. When Ψpd fell below ΨEWP , the forest became insensitive to environmental variation and was a net source of carbon dioxide for nearly 2 months. Thus, ΨEWP is a threshold defining marked shifts in ecosystem functional state. Though there was rainfall-induced recovery of ecosystem gas exchange following soaking rains, a legacy of structural and physiological damage inhibited canopy photosynthetic capacity. Although over 16 growing seasons, only 10% of Ψpd observations fell below ΨEWP , the forest is commonly only 2-4 weeks of intense drought away from reaching ΨEWP , and thus highly reliant on frequent rainfall to replenish the soil water supply. We propose, based on a bottom-up analysis of root density profiles and soil moisture characteristic curves, that soil water acquisition capacity is the major determinant of ΨEWP , and species in an ecosystem require compatible leaf-level traits such as turgor loss point so that leaf wilting is coordinated with the inability to extract further water from the soil.

Measurement of the hydraulic properties of chalk using centrifuge permeameter; the study of chalk hydraulic properties under accelerated gravitational force

In this study, a geotechnical centrifuge has been used to study the unsaturated hydraulic properties of rock samples from the chalk aquifer, SE England. This method allows rapid measurement of hydraulic properties in a controlled environment, in contrast to previous studies on the chalk unsaturated zone, which required either an extended period (years) of data monitoring in the field or extended experimental periods (weeks) in the laboratory. Three types of specially built sensors were used to monitor water flow through chalk samples: a water pressure transducer to measure matric potential, frequency domain reflectometry probes to measure the volumetric water content and pressure transducers to measure the volume of water passing through the sample. Chalk samples were tested during wetting and draining processes to understand any hysteresis occurring during periodic recharge of the aquifer. Before undertaking physical tests of chalk samples in the centrifuge, a theoretical model of chalk hydraulic behaviour under centrifugal force was developed. This model was used to define and justify the instrumentation plan of the physical model and predict the shape of the soil moisture characteristic (SMC) curve and unsaturated hydraulic conductivity ( K u ) function. The results were then evaluated and compared with the experimental results. These results show that chalk samples can be successfully tested under centrifuge conditions and hydraulic properties can be measured, including soil moisture characteristic curves and hydraulic conductivity. Supplementary material: Calculation spread sheets are available at https://doi.org/10.17033/DATA.00000283

Retraction Note: Prediction of soil moisture characteristic curve based on Internet of Things and enterprise e-commerce operation

E-commerce has an important influence on China’s economic and social development. The rapidly emerging Internet of Things and other emerging information technologies can promote the revolutionary innovation and development of e-commerce products and industries. Online direct sales channels fully apply the Internet of Things technology and e-commerce. The operations and channels have more power to apply the Internet of Things technology. If offline business operations have stronger advantages than online e-commerce operations, the Internet of Things technology and the diffusion process are incorporated into the database model; when the proliferation of the Internet of Things remains local, e-commerce operations can only obtain higher efficiency and benefits after applying the Internet of Things technology online, to closely integrate the new generation of information technology with traditional operating strategies. At the same time, government support policies have played an important role in promoting the application of a new generation of information technology. The particle gradation, stress status, dry density, etc., in the soil moisture characteristic curve prediction system may change with the operation of the soil in the atmosphere, and these influencing factors are important measurements that affect soil permeability and land water quality characteristics. The prediction of soil moisture characteristic curve, soil permeability, and soil erosion resistance are linked together, and the study of the influence of these influencing factors on soil permeability and soil moisture characteristics on soil water retention is useful for exploring the mechanism of soil erosion and soil erosion. Sexual control measures have very important guiding significance. Therefore, this paper uses the Internet of Things technology to conduct a detailed study on the prediction content of the soil moisture characteristic curve and the process of enterprise e-commerce operations.

English

The hydraulic properties of soil are very important to determine the soil relationship with water. The Soil Hydraulic Properties (SHP) are used to determine the soil water relationship as it is very crucial for estimation of water holding capacity of soil. In real field conditions, most widely used model for soil moisture retention curves is van Genuchten model. The soil samples were taken randomly from five different depths with three replications of each depth. Moreover, two samples at the depth of 5-35cm and 35-155cm were selected for evaluation of integrated approach to find soil characteristic curves. Soil moisture characteristic curves calculated by integral approach were compared with, soil moisture curves measured by pressure plate apparatus, and Soil Plant Air Water (SPAW) hydrology a computer based Model. The accuracy of results were evaluated by determination of Root Mean Square Error (RMSE), Normalize Root Mean Square Error (NRMSE) and Willmott’s index of agreement (£). A good agreement was observed between integrated approach, high-pressure technique and SPAW model results. In case of integrated method versus high-pressure technique the RMSE was 9.51×10-3 for 5-30cm depth and 8.32×10- 3 for 30-155cm depth. The NRMSEs was 6.52 ×10-2 for 5-30cm depth and 6.1×10-2 for 30-155cm depth, similarly £ was 0.881 and 0.893 for both depths 5-30cm and 30-155cm respectively. Regression coefficient (R2 ) for 5-35cm depth for sorptivity (s) and wetting distance (d) were 0.991 and 0.988 respectively and at depth of 35-155cm, R2 for (s) was 0.990 and for wetting distance (d) was 0.994. In case of integrated method versus SPAW hydrology the RMSEs was 1.3×10-2 for 5-30cm depth and 1.15×10-2 for 30-155cm depth. The NRMSEs for was 9.33 ×10-2 for 5-30cm depth and 7.15×10-2 for 30-155cm depth and similarly £ was 0.852 and 0.863 for both depths respectively. Results indicated a good relationship between high-pressure technique, SPAW hydrology results and integral method. However, integrated approach is best approach to determine the soil moisture characteristics curves of undisturbed and unsaturated soils

Relationship of soil moisture characteristic curve and mechanical properties in Entisols and Inceptisols of Iran

The objective of this research was to investigate the relationship between soil moisture characteristic curve (SMCC) and confined compression curve (CCC), and the ability to estimate the SMCC from the CCC. Five provinces of Iran have been chosen as sampling sites and soil samples (150) were collected from these areas, and some properties of the soil samples were determined. The Gardner model has been fitted to the measured SMCC and CCC. The Gardner model's stress-void ratio coefficients, as well as the CCC properties, were used to estimate the soil moisture at five levels (five classes of variables) through the Gardner model using artificial neural networks (ANNs). A more accurate estimation of the water content was obtained by combining the basic soil properties, and three key properties of soil compression. In addition, the integral root mean square error (IRMSE) in the training and testing steps was reduced from 0.107 and 0.111 to 0.095 and 0.096, respectively. In conclusion, the use of CCC data to estimate the SMCC at all levels of the input variables indicated very favorable results with an increase in the accuracy of the water content estimation between 4% and 16% in both training and testing steps.

RETRACTED ARTICLE: Prediction of soil moisture characteristic curve based on Internet of Things and enterprise e-commerce operation

E-commerce has an important influence on China’s economic and social development. The rapidly emerging Internet of Things and other emerging information technologies can promote the revolutionary innovation and development of e-commerce products and industries. Online direct sales channels fully apply the Internet of Things technology and e-commerce. The operations and channels have more power to apply the Internet of Things technology. If offline business operations have stronger advantages than online e-commerce operations, the Internet of Things technology and the diffusion process are incorporated into the database model; when the proliferation of the Internet of Things remains local, e-commerce operations can only obtain higher efficiency and benefits after applying the Internet of Things technology online, to closely integrate the new generation of information technology with traditional operating strategies. At the same time, government support policies have played an important role in promoting the application of a new generation of information technology. The particle gradation, stress status, dry density, etc., in the soil moisture characteristic curve prediction system may change with the operation of the soil in the atmosphere, and these influencing factors are important measurements that affect soil permeability and land water quality characteristics. The prediction of soil moisture characteristic curve, soil permeability, and soil erosion resistance are linked together, and the study of the influence of these influencing factors on soil permeability and soil moisture characteristics on soil water retention is useful for exploring the mechanism of soil erosion and soil erosion. Sexual control measures have very important guiding significance. Therefore, this paper uses the Internet of Things technology to conduct a detailed study on the prediction content of the soil moisture characteristic curve and the process of enterprise e-commerce operations.

Application of Differential Evolution Cuckoo Search Algorithm in Parameter Optimization of VG Equation

Van Genuchten (VG) equation is the most commonly used equation of soil moisture characteristic curve, and the accuracy of its parameters directly affects the calculation accuracy of soil moisture motion equation. In order to obtain the parameters of the equation more accurately, this paper establishes an optimization model of the VG equation parameters. This optimization model uses the advantages of the cuckoo search algorithm and the differential evolution algorithm to combine the two into a new hybrid cuckoo search algorithm, namely DECS algorithm, and uses this algorithm to solve the parameter optimization problem of VG equation of soil moisture characteristic curve. By collecting and analyzing the relevant experimental data of various soil qualities, the dehumidification and moisture absorption curves of three different soil qualities were selected for simulation calculation. The results show that in the experiment of solving the parameter estimation problem of the VG equation, the DECS hybrid algorithm has better exploration and development capabilities than the cuckoo search algorithm. The hybrid algorithm has relatively significant performance in terms of calculation accuracy and convergence.

Comparison between The Measured and Predicted moisture contents as affected By Some Soil Improvements

Predicted equation were used for best fitting between measured and calculated moisture contents of two soils texture located at Ninevah governorate under the effect of soil improvements . Soil samples were sieved by 2 mm sieves and saturated to measure the soil moisture characteristic curve of 10, 33,100, 200,400, 600,800,1000 and 1500 Kpa. By using both pressure plates and membrane and pressure compared its value by using predicted equations. Results indicated that the values of both Θs and Θr were highest of P3O0 treatment for the clay texture compared with the loamy texture soil.The values of m, n and α of VanGenuchetn equation. for the first location were lower than the second to location and the value of n was higher than both m and α.The value of a of Van&Mua was higher than bmfor the first location than the second one.The value of a of Van&Bur equal to a value of Van&Mua .while b and bˉ were variable and b was lower than bˉ for both locations. The values of a, c and hr were higher for P3O2 treatment of Fred &Xing .compared with the lower values of P0O0 for both location, On the other hand,the a value of Pere&Fred was equal to the same value of both Van&Mua and Van&Bur and the b value equal to Van&Bur and c value was variable and similar to m values of VanGenuchetn .Best fitting between the measured and calculated values at higher suction by Fredlund & Xing equation for both location and at lower suction by (VanGenuchetn, Van&Mua, Van&Bur and Pere&Fred ). Equation VanGenuchetn gave best first to the measured value at 33 Kpa for the second location.while equation Van & Bur gave best first at 100-400 Kpa for both location and Pere&Fred at 33 Kpa for first location.

Effect of biogas waste applications on soil moisture characteristic curve and assessment of the predictive accuracy of the Van Genuchten model

Biogas production has recently become an important issue in countries where alternative energy sources are gaining importance. The study investigates the use of waste, the final product of production, as a soil conditioner and fertilizer for sustainable soil management. The study examines the effects of different amounts of biogas waste [0 (B0), 1 (B1), 2 (B2), 3 (B3) and 4 (B4) ton da-1] on some soil properties and soil moisture characteristic curve (pF). In addition, the van Genuchten model, which has been long and widely used in many studies for the prediction of hydraulic properties, was compared with the pF curves that were obtained using the predicted and real values obtained from the applications. The results of the study showed that although biogas waste applications were more effective in the wet region of the moisture characteristic curve, B3 was the most effective dose that improved the physical properties of the soil. The B4 application had a decrease of about 16% in the penetration resistance and an increase of about 21% in the wilting point compared with those of the control group. The decrease in the macro pore volume due to biogas waste applications was not statistically significant, while biogas waste applications caused a statistically significant increase in the micro pore volume (P <0.05). Among the van Genuchten model parameters, the moisture content in saturation (θS) and residual water (θr) had realistic results in all biogas waste applications. Moreover, the air entry value (1 / α) was estimated to be 41.667 cm in the B0 application and 55.556 cm in the B4 application. In conclusion, high-accuracy estimates were obtained using the van Genuchten model with a R2 value of 0.901 and root mean square error (RMSE) value of 0.061 cm3 cm-3 in the moisture characteristic curve of the control (B0) soil.

The use of pore volume characteristics and soil moisture release curve to determine physical quality of soils with different gypsum contents

"A newly proposed concept of soil physical quality and its development as a guide to assess the extent of soil degradation or improvement and to determine appropriate soil management. The study aimed to: evaluate the soil physical quality index of gypsiferous soils under different management systems as well as determine the optimal pore size distribution and the optimum moisture-tension curve based on the quality of the physical soil properties under different management systems and diagnose the distribution of pore sizes and moisture-tension curves that could be used to predict the changes in the physical quality of gypsiferous soils because of the applied agricultural management pattern. Physical indicators measured on undisturbed soil samples collected from 15 selected sites in Salah Aldeen Governorate, with different gypsum content (30 to 301 g kg-1 soil). The results showed that the best distribution of measured pore size (h) S *, (Normalized pore volume) was for a group of soils that were largely similar in terms of shape and location parameters. Accordingly, the optimal pore distribution considered representative of these soils. The results showed the possibility of using the (Dexter-S) indicator correctly and in coordination with the distribution of pore size and the soil moisture characteristic curve to calculate the physical soil quality in soils of different gypsum content.

Correction to: Assessing an efficient hybrid of Monte Carlo technique (GSA-GLUE) in Uncertainty and Sensitivity Analysis of vanGenuchten Soil Moisture Characteristics Curve

Correction to: Assessing an efficient hybrid of Monte Carlo technique (GSA-GLUE) in Uncertainty and Sensitivity Analysis of vanGenuchten Soil Moisture Characteristics Curve

Assessing an efficient hybrid of Monte Carlo technique (GSA-GLUE) in Uncertainty and Sensitivity Analysis of vanGenuchten Soil Moisture Characteristics Curve

Studying model uncertainty and identifying the parameter uncertainty in the modeling of water flow through the soil is useful to improve water and soil management. This research aimed to assess the uncertainty of the parameters of soil water retention curve (SWRC) models using an efficient hybrid of the Monte Carlo technique e.g. generalized likelihood uncertainty estimation (GLUE). GLUE estimates the parameters of vanGenuchten, vanGenuchten-Mualem, and vanGenuchten-Burdine models for four soil classes. Also, to evaluate the relative importance of the model parameters, generalized sensitivity analysis (GSA) was performed. The results of the uncertainty analysis showed that among the studied models, the vanGenuchten-Mualem model with the indices of S = 0.05, T = 0.4, d-factor = 0.25 and, PCI = 100 was considered as the most accurate model with the least uncertainty. Also, the results of GSA were demonstrated that alpha and n parameters were sensitive parameters in the models. Consequently, identifying the uncertainty of the SWRC model structure and its parameters, relevant models with higher accuracy can be used in the study of soil water processes, and better water resource allocation.

Validation and Modification of the Van Genuchten Model for Eroded Black Soil in Northeastern China

The soil water characteristic curve is highly related to soil physical characteristics, which may be affected by the soil erosion degree. To explore the applicability of the soil moisture characteristic curve model in northeastern China, two erosion degrees, (1) lightly and (2) severely eroded black soil sampled from 15 sites, were collected. The soil water contents at eight soil water suctions were measured and the parameters of the Van Genuchten (VG) model were estimated. Then, two input sets—SSCBD (sand, silt and clay percentages and bulk density) and SSCBDθ33θ1500 (SSCBD, and water contents at 33 and 1500 kPa suction) based on the Rosetta model were compared for the VG model prediction. The results showed that the parameters in the VG model had significant difference under the two eroded soils of the saturated water content (θs), but the opposite was true for the residual water content (θr), the scale parameter (α) and the shape parameter (n). In addition, the θs and θr had no significant differences but the opposite was true for the α and n under the two input sets. The simulated soil water content values of the VG model parameters derived from the Rosetta model underestimated the measured ones, except the water contents at 0 kPa. Therefore the relationships between m and n were modified for accuracy. The validation results showed that the VG model performed well when the sand content was less than 80% for the input set of SSCBD. Using the input set of SSCBDθ33θ1500 can lead to higher simulation accuracy and wider applicability compared with SSCBD under black soil.

Soil Organic Carbon and Soil Physical Characteristics as Affected by Land Uses under Semiarid Irrigated Conditions

ABSTRACT Rice-Wheat rotation is the dominant land use in the state of Punjab, resulting in over exploitation of ground water resources. Thus, it is necessary to evaluate other land uses that requires less water and are sustainable. The present investigation was planned with four land uses viz., fallow (FLU), rice-wheat (ALU), grasses (GLU) and pear (PLU) with respect to their effect on soil organic carbon and soil physical characteristics in surface and subsurface depth in district Ludhiana, Punjab. The soil organic carbon (SOC) content was higher by 10, 30.9 and 24.9% under rice-wheat, grasses, and pear than that under fallow. The grasses showed higher soil moisture characteristics curve (SMCC) and lower bulk density (Db) than that under rice-wheat. The larger mean weight diameter (MWD) were observed under pear, grasses and fallow than that under rice-wheat by 0.21, 0.51 and 0.41 mm, respectively. The saturated hydraulic conductivity (Ks) was higher in magnitude by 56.1, 55.4 and 28%, respectively under PLU, GLU and FLU over ALU. Of the evaluated land uses, pear and grasses proved to be more sustainable by retaining more moisture, maintaining better soil physical characteristics and SOC under semiarid irrigated conditions in the state on long term gradual response.