Measurement Of Soil Compaction Research Articles

Development of a tire testing machine for evaluating the performance of tractor tires based on the soil compaction

Soil compaction, which is more effective than soil shear owing to the weight of tractor tires, reduces sugarcane cultivation. Instead of a field study, a single-wheel tester is more suitable for studying the tractor tire tracks on a soil bin in a laboratory. However, the soil compaction measurement is time consuming and analyzes the bulk density only at the sampling point of the track. In this study, a tire-testing machine (TTM) was developed to evaluate tractor tire performance based on soil compaction. A 3D scanner was employed to model the tractor tire track on a sandy clay loam soil, which is suitable for sugarcane planting in Thailand. Mathematical models for soil bulk density prediction were proposed and used to transform the 3D footprint model into a 3D color contour of the soil bulk density. The soil compaction effect of tractor tires at three different tread depths was evaluated. It was found that deeper treads caused higher soil bulk density than shallow treads. Static tires induce greater soil bulk density than rolling tires. This novel TTM with measurement techniques is a novel method for evaluating the tire-soil compaction in crop fields. It can also guide farmers to purchase suitable agricultural tires.

A tractor hydraulic assisted embedded microprocessor-based penetrometer for soil compaction measurement

Measurement of soil compaction in terms of penetration resistance using a hand penetrometer requires more time and effort. A tractor hydraulic-assisted embedded microprocessor-based penetrometer was developed to make the results easy to monitor and decrease human error. The developed penetrometer consisted of a driving system for pushing the penetrometer probe into the soil at a desired speed, a sensor unit (load cell and ultrasonic sensor) for measuring the force required to push the probe and the depth of penetration, and a data logging system. The embedded system of the penetrometer comprised various components: Arduino Uno microcontroller, I2C, WiFi module, and HX711 amplifier. The system was able to measure a soil penetration resistance of 5000 kPa up to a depth of 500 mm. A WiFi module helped to transmit the data to an Android mobile application. The acquired data also include date/time parameters along with latitude and longitude locations picked up from the GPS of the mobile. Its performance was assessed based on sensor characteristics such as accuracy, sensitivity, non-linearity, and non-repeatability. The average and maximum absolute variations in the cone index values measured with developed system and a hand-held digital penetrometer were observed to be 22.50% and 27.88%, respectively.

The response of potato crop to the spatiotemporal variability of soil compaction under centre pivot irrigation system

AbstractPrecision agriculture techniques were employed to study the impact of the spatiotemporal variations of soil compaction on the performance of potato crop during its various growth stages. The study has been conducted on a 30 ha centre pivot irrigated potato field, located in Wadi Al‐Dawasir area in Saudi Arabia. In situ soil compaction measurements were collected, in conjunction with Sentinel‐2A satellite data, and correlated spatiotemporally against potato crop growth and yield parameters. The univariate and bivariate Moran's function (Moran's I), the linear regression and the analysis of variance (ANOVA) techniques were used to analyse the data and examine the interrelationships. The spatial correlations between the measured variables revealed high clustering, producing Moran's I of 0.87, 0.79 and 0.57 for soil compaction, yield and normalized difference vegetation index (NDVI), respectively. Compaction‐yield relationship revealed a relatively high significant negative spatial correlation (Moran's I = 0.68). While, the spatial correlation between the average values of compaction and NDVI has negatively produced a Moran's I value of 0.45 (at 0.001 significance level), when 999 permutations were tested for all relationships. A significant positive correlation was observed between high compaction and high proportion of small size tubers, with R2 and P > F values of 0.65 and .0001, respectively. In contrast, a significant negative correlation has been obtained between high compaction and high proportion of large size tubers, with R2 and P > F values of 0.57 and .0001, respectively. Understanding the causes of disparity in the productivity of agricultural fields will help decision‐makers and farmers to take proactive actions towards better agricultural practices.

Real-Time Monitoring of Soil Compaction Using Piezoceramic-Based Embeddable Transducers and Wavelet Packet Analysis

Quantitative assessment of soil compaction is of great importance to construction work, precision agriculture, and geotechnical research. Currently, measurement of soil compaction is mainly performed through field measurements, and the accuracy is highly influenced by personnel experience. In addition, most of the current methods for soil compaction measurement are capable of real-time monitoring. This paper presents an exploratory study of using a piezoceramic-based active sensing approach coupled with wavelet packet analysis to quantitatively monitor soil compaction in real time. In the active sensing approach, a pair of smart aggregates (SA) consisting of piezoceramic transducers embedded inside a host material are embedded into soil. In the pair, one SA acts as transmitter to transmit a modulated stress wave towards the other SA, which acts as receiver. The attenuation ratio of the stress wave propagating energy in soil is governed by the degree of soil compaction, so that the received wave properties of the smart aggregate sensor can be further characterized by using wavelet packet as an index to evaluate the soil compaction in real time. Integrated with remote sensing technologies, the proposed method has potential to be utilized as a real-time remote-sensing technology, which can offer a solution in the monitoring the degree of soil compaction.

3D finite element simulation of a single-tip horizontal penetrometer–soil interaction. Part I: Development of the model and evaluation of the model parameters

A fundamental step to employing a horizontal penetrometer for on-the-go measurement of soil compaction is to characterize the horizontal penetrometer resistance (PR) as affected by soil mechanical/physical properties and design/operational parameters of the penetrometer. Such complicated soil–tool interactions are preferably investigated using numerical analyses, e.g. finite element (FE) method. A symmetric 3D FE model for a single-tip horizontal penetrometer–soil interaction was developed and evaluated in ABAQUS/Explicit. In the first paper of this study, we focus on the development of the model and the evaluation of some affecting parameters, namely (i) boundary effects, (ii) element size (mesh density) around the conical tip of the penetrometer, (iii) sensitivity of the predicted PR with respect to (a) soil mechanical properties (b) tip extension (i.e. the distance between cone base and shin of the carrying tine), (c) working depth, and (iv) soil layering and the effect of working depth in relation to the tine critical depth. The elastic–plastic parameters of the soil constitutive model (Drucker–Prager) were determined from samples taken within the working depth of the penetrometer in a soil bin. The results showed that for the tested penetrometer dimensions and the given soil specifications (i) the simulated soil box should be at least 0.8m long and 0.4m wide to avoid interference from the boundaries on predicted PR; (ii) the element size around the cone should be fine enough (9mm) for a stable steady-state simulated PR; and (iii) the tip extension must be >4cm to avoid the effect of tine on PR. PR was found to be most sensitive to soil internal angle of friction and compressive yield stress, whilst Poisson's ratio had no significant effect, and Young's modulus of elasticity and soil-metal coefficient of friction showed only minor impacts on PR. Due to soil surcharge, PR increased by 30% when increasing the working depth of the penetrometer from 5 to 40cm in a homogenous soil profile. An effective radius of 6cm was found for the soil failure around the cone. The simulations showed that when the cone was located above the tine critical depth (i.e. inside the crescent failure zone), the PR was lower and the PR signal was unstable compared with when the cone worked out of crescent failure zone at the same depth. The model developed here can be used to characterize PR with respect to the state of soil strength/compaction across soil types.

Use of a triple-sensor fusion system for on-the-go measurement of soil compaction

A general approach to mapping the within-field spatial variation in soil compaction is to measure a soil strength index such as penetrometer resistance (PR) using an on-the-go mechanical sensor. In general, these types of measurements depend on a number of soil properties, such as dry bulk density (ρd), organic matter (OM) content, water content (θ) and clay content (CC), and thus only provide a composite soil parameter that is somewhat inadequate for characterising the soil compaction status. In this study, a novel sensor fusion is proposed that combines a single-probe horizontal penetrometer, a dielectric-type soil water content sensor and a γ-ray sensor (the Mole) for simultaneous measurement of PR, volumetric water content (θv) and CC, respectively. In order to examine the applicability of the system for on-the-go measurement of soil compaction in terms of ρd, experiments were conducted in two fields with CC of 148–313gkg−1. At 48 selected locations along transects where on-the-go measurements with the triple-sensor system were performed, core samples for determination of CC, OM, θv and ρd were taken within the working depth of the horizontal penetrometer. A four-parameter statistical model was developed for ρd as a function of PR, θv and CC based on the soil core (for ρd, θv and CC) and sensor measurements (only for PR) with R2=0.71 and RMSE=0.06Mgm−3. The model was employed to predict the spatial variations in ρd over one of the fields (for which a yield map was available) using the continuous sensor system data. Interpolated maps of crop yield, PR, θv, CC and ρd showed some similar local patterns at field scale. The sensor fusion system developed here can be a useful instrument for future studies on soil compaction, especially within the context of precision agriculture. Further evaluation of the sensor system over a wider range of soil texture and water content could provide an extensive data base for developing a general pedotransfer function for ρd as a function of sensor-based readily-measurable soil attributes.

Modeling of electrical resistivity and maximum dry density in soil compaction measurement

This paper presents the mathematical relationship of electrical resistivity and dry density in compacted soil through electrical signal for geotechnical investigations. Monitoring of the compacted soil through electrical conductivity plays an important role in the construction of highway embankments, earth dams and many other engineering structures. Conventionally, soil compaction is measured through the estimation of maximum dry density at optimum moisture contents in laboratory tests. This conventional testing method is very tedious and costly especially when a lot of samples are involved. In this work, a mathematical model is developed to estimate the soil compaction on-site through electrical resistivity corresponding to the percentage of moisture contents in the compacted soil. The practical usage of the derived mathematical model is demonstrated using several soil samples for various types of soil.

Impacts of Construction Activity on Bioretention Performance

Bioretention cells are incorporated as part of low impact development LID because of their ability to release influent runoff as exfiltration to the soil or evapotranspiration to the atmosphere. However, little care is taken as to the techniques used to excavate bioretention cells, and there is little concern as to the soil-moisture condition during excavation. Certain excavation techniques and soil-moisture conditions create higher levels of compaction which consequently reduce infiltration capacity. Two excavation techniques, the conventional method which purposefully smears the underlying soil surface and the method which uses the teeth of an excavator's bucket to scarify the underlying soil surface, were tested. Field tests were conducted on three soil types sand, loamy sand, and clay under a variety of antecedent soil-moisture conditions. Multiple hydraulic conductivity, surface infiltration, and soil compaction measurements were taken for each excavated condition. In all cases, the rake method of excavation tended to yield more permeable, less compacted soils than the scoop method. The difference of infiltration and hydraulic conductivity between the two excavation techniques was statistically significant p0.05 when tests were conducted in wet soil conditions. Also, the infiltration rate at the clay site was significantly lower p0.05, and the hydraulic conductivity at the sandy site was significantly lower p0.05 when the scoop methodology was used. Based on results of the experiment and because essentially no extra cost is associated with the rake method of excavation, it is recommended over the conventional scoop method. Another recommendation is to excavate under relatively dry soil conditions. The use of the rake method under dry soil conditions is expected to increase long-term exfiltration from bioretention cells.

Expanding implementation of an on-line measurement system of topsoil compaction in loamy sand, loam, silt loam and silt soils

A previously developed model for on-line prediction of soil compaction indicated as bulk density (BD), was limited in use for a sandy loam field. This study was undertaken to investigate the possibility of modifying this model for new soil textures, namely loamy sand, loam, silt loam and silt soils. Using the on-line measurement system of BD, measurements were carried out in four fields with different average textures of loam, sandy loam and silt loam and silt loam/silt fields. The on-line measurement system used consisted of a subsoiler, whom draught ( D) was measured with a single shear beam load cell and depth ( d) was measured with a wheel gauge consisted of a swinging arm metal wheel equipped with a linear variable differential transducer (LVDT). The soil gravimetric moisture content (MC) was measured with the oven drying method. The on-line measured BD was compared with measured BD with Kopecki rings (core sampling method) (736 samples), to validate the potential use of this sensor in the new studied soil textures. Results showed that the BD model can be used for on-line measurement of soil compaction for the selected textures. It was found that the correction factor ( M) of this model was mainly sensitive to variable MC, and slightly sensitive to clay content. The M at field scale varied between 0.994 (silt loam/silt soil with an average MC of 0.279 kg kg −1) and 1.171 (loam soil with an average MC of 0.105 kg kg −1). At almost the same texture, M varied between 1.171 for an average MC of 0.105 kg kg −1 and 1.122 for an average MC of 0.186 kg kg −1, which proves the domination of MC effect on M. The multiple linear regression (MLR) analysis (analysis of variance (ANOVA)) performed between MC and clay and M retained MC as M predictor ( P < 0.001, R 2 = 0.86). This MLR resulted in similar prediction accuracy of compacted zones as compared to the linear regression model between MC and M. In a variable texture field, the corrected BD model resulted in remarkable spatial similarity of BD between the corrected on-line and core sampling method. Therefore, it can be concluded that the BD model with the new M can be used for on-line measurement of soil compaction in loamy sand, sandy loam, loam, silt loam, and silt soils at different MC, bearing in mind that the difference in clay content is minimal (83–175 g kg −1).

Comparing Peak and Residual Soil Pressures Measured by Pressure Bulbs and Stress-State Transducers

Measurement of soil compaction caused by vehicle loading is difficult and often subject to extreme variability. Two types of soil transducers were compared in an experiment conducted in a Norfolk sandy loam soil in the USDA-ARS National Soil Dynamics Laboratory's (NSDL) soil bin facilities. Stress-state transducers (SSTs), electronic transducers developed at the NSDL for measuring six directional pressures and determining the stress state, were used for this experiment. Rubber bulbs connected by a rubber hose to a dial pressure gauge, which measure hydrostatic pressure, were also used in this experiment. Both transducers were buried at depths of 7.5, 15, or 23 cm and were used to measure soil pressures caused by a 30.5L-32 tire with dynamic loads of 19 or 37 kN. The SSTs were buried by inserting them into an excavated hole, while the rubber bulbs were inserted with a special tool designed to leave the soil surface and surrounding soil undisturbed. Peak values of mean normal stress (calculated from measurements of pressure) from the SSTs and hydrostatic pressure measured with the rubber bulbs were found to be affected by both loading and burial depth. Similar magnitudes and variation were observed for each transducer. Residual pressure, defined as the pressure remaining after loading was removed, was found to be affected by both loading and burial depth when measured with the rubber bulbs. Continued development and testing of the rubber bulb transducers could provide a simple method of determining levels of compaction that could damage soils and thus prevent excessive trafficking.

Field Calibration and Spatial Analysis of Compaction-Monitoring Technology Measurements

To implement compaction-monitoring technologies (i.e., continuous compaction control and intelligent compaction), robust and versatile specifications are needed. These specifications require field calibration of the various machine sensor outputs to in situ soil compaction measurements. The goal of this study was to provide insights into (a) the nature of compaction-monitoring measurements, (b) how the measurements are related to soil properties determined from in situ compaction control tests, and (c) how compaction-monitoring technology may be addressed in specifications for using the technology in practice. To accomplish this goal, testing was conducted on one-dimensional test strips with several nominal moisture contents for developing statistical regression models that relate machine drive power and compaction meter value data to engineering and index properties of soil. In addition, a two-dimensional test area with variable lift thickness and moisture content was constructed and tested by using both compaction-monitoring technology and in situ devices (e.g., nuclear moisture-density gauge, portable falling weight deflectometer). The spatial distribution of the data was investigated. The significance of this research is that it represents the first documented field calibration of both one-dimensional and two-dimensional tests areas on similar soils and introduces a new approach to generating pass-fail criteria based on compaction-monitoring technology.

On-the-go measurement of soil water content and mechanical resistance by a combined horizontal penetrometer

A combined horizontal penetrometer was designed for the on-the-go and simultaneous measurement of soil water content and mechanical resistance. The maximum sampling rate for both sensors was 10 Hz and the maximum operating depth was 20 cm. For the water-content sensor, its measurement principle depends on the electric field of the fringe-capacitance. In order to evaluate the applicability of this combined penetrometer, four experiments in the field were carried out. These experiments included: (1) soil water content profiles test; (2) soil compaction measurement test; (3) effect of the operating velocity on the water content and resistant force measurement; (4) effect of operating depth on the force measurement. The experimental results show that the combined horizontal penetrometer is a practical tool since it can provide more useful information of soil physical properties.

Development of on-line measurement system of bulk density based on on-line measured draught, depth and soil moisture content

On-line measurement of soil compaction is needed for site specific tillage management. The soil bulk density ( ρ) indicating soil compaction was measured on-line by means of a developed compaction sensor system that comprised several sensors for on-line measurement of the draught ( D) of a soil cutting tool (subsoiler), the soil cutting depth ( d) and the soil moisture content ( w ). The subsoiler D was measured with a single shear beam load cell, whereas d was measured with a wheel gauge that consisted of a swinging arm metal wheel and a linear variable differential transducer (LVDT). The soil w was measured with a near infrared fibre-type spectrophotometer sensor. These on-line three measured parameters were used to calculate ρ, by utilising a hybrid numerical–statistical mathematical model developed in a previous study. Punctual kriging was performed using the variogram estimation and spatial prediction with error (VESPER) 1.6 software to develop the field maps of ρ, soil w , subsoiler d and D, based on 10 m × 10 m grid. To verify the on-line measured ρ map, this map was compared with the map measured by the conventional core sampling method. The spherical semivariogram models, providing the best fit for all properties was used for kriging of different maps. Maps developed showed that no clear correlation could be detected between different parameters measured and subsoiler D. However, the D value was smaller at shallow penetration d, whereas large D coincided with large ρ values at few positions in the field. Maps of ρ measured with the core sampling and on-line methods were similar, with correlation coefficient ( r) and the standard error values of 0.75 and 0.054 Mg m −3, respectively. On-line measured ρ exhibited larger errors at very dry zones. The normal distribution of the ρ error between the two different measurement methods showed that about 72% of the errors were less than 0.05 Mg m −3 in absolute values. However, the overall mean error of on-line measured ρ was of a small value of 2.3%, which ensures the method accuracy for on-line measurement of ρ. Measurement under very dry conditions should be minimised, because it can lead to a relatively large error, and hence, compacted zones at dry zones cannot be detected correctly.

An Automatic Depth Control System for Online Measurement of Spatial Variation in Soil Compaction, Part 4: Improvement of Compaction Maps by using a Proportional Integrative Derivative Depth Controller

The spatial variation in soil compaction is inaccurately measured online (on-the-go, tractor-based continuous measurement) if the measured depth d is not controlled at minimum variations. A depth control system is needed for controlling the depth of the subsoiler used as a tool for online measurement of soil compaction indicated as dry bulk density ρ d . A proportional integrative derivative (PID) controller with a filter on the derivative-action that provided the best results in a previous part of this study was implemented. For continuous interpolation of online measured dry bulk density and sensor depth, kriging was performed with Variogram Estimation and Spatial Prediction with ERror (VESPER 1·6) software to develop maps with irregular grid of 0·3 m by 10 m. The VESPER 1·6 software was also used to generate the field maps of dry bulk density with 10 m by 10 m grid. To verify the online measured dry bulk density maps, the 10 m by 10 m online measured dry bulk density maps were compared with maps measured by the conventional core sampler method. Results showed that compaction maps developed with 10 m by 10 m grid were totally different from corresponding maps developed for continuous data of 0·3 m by 10 m grid. The PID controller considerably reduced the variation range in depth of the sensor. In comparison with the conventionally measured soil dry bulk density map, the spatial variation of online measured dry bulk density was improved when the PID controller was implicated. In addition, the PID controller with low soil moisture content variation led to a strong similarity between draught and soil dry bulk density. The automatic depth control system also assisted tracing the tramlines on compaction maps developed by elimination of possible variation in measured soil dry bulk density that could result from variable depth. The PID controller eliminated a partial similarity between compaction and depth maps that occurred without the depth control system.

An Automatic Depth Control System for Online Measurement of Spatial Variation in Soil Compaction, Part 1: Sensor Design for Measurement of Frame Height Variation from Soil Surface

A swinging arm type of frame height sensor was designed to measure the distance variation between the soil surface and the frame of a sensor system developed for the online measurement (tractor-based continuous measurement) of the spatial variation in soil compaction. A linear variable displacement transducer (LVDT) with a 0·2 m stroke length was used to connect the frame to a metal wheel of the frame height sensor at the axle of the wheel. An analytical–statistical hybrid model was developed for the direct calculation of the frame height variation. Tests were performed on four surfaces: asphalt road; rough dirt track; and agricultural silty clay loam soil (bare soil and soil with stubble present). The results were compared with ultrasonic measurements to validate the sensor. An excellent correspondence of distance measurement was found between the two sensors with a standard error (SE) of 0·0033 m and with a high determination coefficient R2 of 0·93. However, the measurement of the frame height was found to be exaggerated when using the wheel-LVDT sensor on the dirt track, which was attributed to the wheel sinkage in the loose soil. Although the standard error between the wheel-LVDT measurements and ultrasonic distance measurements was still low (0·0049 m) for the dirt track, this was higher than that found on the asphalt road. Similarly, the trajectories of the frame height measurement performed on the field showed a good correspondence between the wheel-LVDT sensor and the ultrasonic sensor. The wheel-LVDT sensor measured a slightly larger height than the ultrasonic sensor, with mean deviations ranging between 0·018 and 0·021 m. In comparison with the standard error (0·035 m) of the measurement line with maize stubble, lower standard errors of 0·0064 and 0·0088 m with high R2 were found for the bare soil surface without and with subsoiler, respectively. Pressing of the stubble by the relatively large mass of the wheel of 175 N made the measurement of frame height variation with the wheel-LVDT sensor apparently less affected by stubble compared to the measurement with the ultrasonic sensor. Therefore, the wheel-LVDT sensor can be used more accurately than the ultrasonic sensor, in fields covered with plant residues and stubble, providing the input for the position control of the tractor three-point linkage aiming at online measurement of soil compaction at constant depths. Based on a certain soil type, moisture content and dry bulk density, correction factors need to be selected and subtracted from the wheel-LVDT sensor output to compensate for the extra distance measured due to the wheel sinkage on a bare soil surface.

Terramechanics research in the Soil Section of the Scottish Institute of Agricultural Engineering

This is a documentary article describing the Institute's work concerning terramechanics. A brief history of the Soil Section outlines its purpose in relating the characteristics of agricultural machinery, the physical properties of soils and crop growth behaviour. The facilities of the Soil Section are described and its success in developing a high-resolution gamma-ray probe to measure soil bulk density and a recording penetrometer is described. Soil compaction measurements have been carried out for alternatives to the conventional tractor wheel and use of a drop-cone to measure soil plastic limit has been developed. Current efforts are focused on performance measurements of multiple-wheel configurations, four-wheel-drive tractors, consideration of soil compaction under modern crawler tracks and research on the effects on crop yield of soil loosening below normal ploughing depth. Development of prediction models for soil compaction is a major interest.

Laboratory Measurement of Soil Compaction and Plastic Flow

Laboratory Measurement of Soil Compaction and Plastic Flow