Penetration Resistance Measurements Research Articles

An inexpensive and lightweight dynamic cone penetrometer for the characterization of shallow submerged sediments

Abstract Sediment compaction is an indicator of the health of benthic communities. At the same time, many of the extractive or cultivation activities on the coast take place in areas of special environmental interest and remove or compact the sediment by their own activity or simply by access on foot. Measurements of compaction or penetration resistance of marine or river sediments are not common, especially in submerged environments. Although there are devices, such as vane testers, that can be used in non‐submerged sediments, lightweight and inexpensive devices for measuring compaction in submerged sediments are rare. An apparatus for measuring sediment penetration resistance based on the dynamic cone penetrometers used in terrestrial environments is described and tested. The device is lightweight and inexpensive, and although it is intended for use in submerged sediments, it can also be used manually in sediments accessible by foot. In the process of testing the apparatus, the penetration resistance values of surfaced sediments have been compared with those obtained with a vane tester to estimate compaction. This new lightweight penetrometer provides inexpensive penetration resistance values as a measure of compaction in the sediment layer of greatest interest for the management of habitats and communities and makes it possible to establish criteria for action and to measure its effectiveness.

Applicability of soil‐type index for shear wave velocity‐based liquefaction assessment

AbstractThe current simplified liquefaction assessment method based on the shear‐wave velocity, Vs has uncertainties about how the fine contents change the Vs‐based liquefaction resistance. According to the simplified method, for a given Vs, the cyclic resistance ratio (CRR) increases with an increase in fine contents. However, field investigations recently revealed that for various silty sands, the correlation between CRR and Vs is soil‐type index dependent and not specific for all sand‐silt mixtures with the same fine contents. Therefore, a detailed experimental research program is performed in this study to clarify the effect of the soil‐type index on the shear wave velocity and CRR correlation. In the first part of the present study, the cyclic resistance of sand mixed with non‐plastic (NP) fines (dry weight of 0%, 5%, 15%, and 35%) was investigated using cyclic direct simple shear (CDSS) tests. Seismic cone penetration (SCPT) tests were performed inside the large‐scale box to facilitate normalized cone penetration resistance (qc1N) and shear wave velocity measurements on the soils used in the CDSS tests. A new correlation was proposed between the qc1N and normalized shear wave velocity (Vs1) using the soil‐type index Ic representing the behavior of soil. Then, CRR‐Vs1 correlation was obtained experimentally for four distinct ranges of soil‐type index. Finally, the results of this study and the proposed CRR‐Vs1 trends in other investigations were used to discuss the soil‐type dependent Vs‐based liquefaction susceptibility zones.

Using Models and Artificial Neural Networks to Predict Soil Compaction Based on Textural Properties of Soils under Agriculture

This study focuses on addressing the challenges associated with labor-intensive soil penetration resistance (SPR) measurements, which are prone to errors due to varying soil moisture levels. The innovative approach involves developing SPR estimation models using artificial neural networks (ANN) for soils with optimal moisture levels determined by van Genuchten (WG) calculations. Sampling and measurements were conducted at 280 points (0–30 cm depth), with an additional 324 samples used for model testing. Considering six scenarios, this study aimed to identify the best estimation model using key soil properties (sand, clay, silt, bulk density, organic carbon, and aggregate stability) in different combinations affecting SPR. Results from all ANN scenarios demonstrated satisfactory SPR estimation performance, with the sand and clay content scenario exhibiting the highest accuracy, characterized by a mean square error (MSE) of 0.0029 and a coefficient of determination (R2) value of 0.9707. This selected scenario were further validated with different test data, yielding an MSE of 0.7891 and an R2 value of 0.67. In conclusion, this study suggests that, by standardizing moisture levels through WG calculations, ANN-based SPR estimation can effectively be applied to soils with specific sand and clay contents.

Can we use X-ray CT to generate 3D penetration resistance data?

Noninvasive imaging of soils with X-ray CT has proven to be a useful method to assess soil structure from a pore space perspective. In contrast, methods like cone penetration tests reflect soil structure from the perspective of the soil matrix as assessed by its mechanical strength. Because both the gray value (GV) obtained with X-ray CT and the penetration resistance (PR) obtained with a cone penetration test depend on soil density there should be a relationship between the two. To the best of our knowledge, no studies attempted so far to investigate the nature of the PR ∼ GV relationship and to understand how well PR and GV are correlated. We aimed at bridging that gap and carried out a combined analysis of local GV and PR with undisturbed soil cores sampled in two soil textures, i.e., loam and sand. To carry out the GV measurements, we developed a new approach which considers an adaptive volume of the zone of influence of the penetrometer tip as a function of soil density. For sand and when looking at samples individually, the correlation between PR and GV was best when the soil microscale heterogeneity was high, i.e., when dense and loose zones of soil were present on the course of the penetrometer tip. For loam, the correlation between PR and GV was not dependent on soil heterogeneity. When looking at the whole dataset, the agreement between PR and GV was better in loam than in sand, with a distance correlation metric of 0.66 for loam and 0.34 for sand, respectively. For loam, the relationship PR ∼ GV had a trend which was similar to that of a hyperbola, i.e., with escalating PR values in a narrow GV range. For sand, no particular model could be recognized. In order to provide a proof-of-concept on how to generate 3D PR maps, the co-located measurements of GV and PR were used to establish an empirical relationship and X-ray CT was used to extrapolate it in 3D. This was carried out with the loam dataset by fitting a hyperbolic function to the PR ∼ GV data pairs. This model was then used to convert GVs into PR values, at a spatial resolution equal to that of the shaft diameter of the penetrometer tip we have used. Notwithstanding the fact that the suggested approach is dependent on numerous experimental conditions and edaphic factors, we advocate for the use of 3D PR maps. These maps could be used in root-soil interactions research, for which the study and breeding of cultivars that could show plastic response in their root systems under mechanical stress is becoming more and more important. This is particularly relevant in the context of mechanized modern agriculture.

Development of a new T-bar for the geotechnical centrifuge at TU Delft

An accurate estimation of undrained shear strength of clay seabed is important for interpreting lateral pile-soil interaction response. The cylindrical T-bar is a widely used site investigation tool for profiling the undrained strength (su) of soft soils. As such, a new miniature T-bar penetrometer is designed and fabricated at TU Delft for characterization of the undrained shear strength profile of clay layer in centrifuge models, and OCR profile can be then derived from undrained shear strength profile with known pre-consolidation stress level. The miniature T-bar penetrometer head is a cylinder of 5 mm in diameter and 20 mm in length and the miniature T-bar penetrometer head is connected with a rigid shaft (Figure 1(a)). The T-bar penetration resistance along the depth of clay sample can be obtained and further interpreted into the undrained shear strength profile.
 Rate of penetration is one of the key parameters that govern the drainage behaviour of soil response around the T-bar and the resulting penetration resistance. A very low rate of penetration leads to partial pore water dissipation and thus partial drainage condition. When a very large rate of penetration is applied, the fully undrained condition is achieved. However, the effect of T-bar penetration rate has not previously been fully examined for normally consolidated and over consolicated clay in the centrifuge. In this paper, the tip resistance profile of T-bar penetration tests under different rates of penetration is analyzed to obtain undrained shear strength profile of clay soils.
 A series of T-bar tests are conducted in both normally consolidated and slightly over consolidated clay samples at 100 g. The sample drainage state is tested by varying the rate of penetration from 0.01 mm/s to 5 mm/s. The results are interpreted by two methods: (i) the conventional method by converting the measured penetration resistance to soil strength using a single bearing factor, indicating a full-flow mechanism at failure [1]; and (ii) an approach considering soil buoyancy and a reduced bearing factor arising from the shallow failure mechanism, indicating the shallow correction procedure has a significant influence on the soil strength profile inferred from a T-bar penetrometer test [2]. The interpreted undrained shear strength profile provides soil property and OCR information for further monopile tests in the centrifuge, allowing a comprehensive study of the soil-structure interaction on soft soils.

Soil Density in Traditional Mouldboard Tillage

Abstract Until recently, mouldboard ploughing was used as the main tillage in almost the entire territory of Ukraine and Russia. However, mouldboard technologies contribute to the formation of a “plough pan”, which contributes to additional soil compaction. The intensity of agricultural production exacerbated the problem of soil compaction by machine and tractor units. The over-consolidation of soil results in stunted plant root growth, lack of oxygen, and water and nutrient restrictions. Soil compaction can be reduced by deep local chiselling. The aim of the study was to determine the density of the soil at different depths during continuous traditional cultivation (reverse ploughing). The density of the soil was evaluated by resistance to penetration into the soil in a vegetable-forage crop rotation on an experimental field with continuous traditional tillage. The measurement of penetration resistance was carried out using an automatic electronic hardness tester “DATAFIELD”. The boundaries of the experimental field were determined, a computer map of the experimental field was compiled with automatic “grid” of plot sizes, two-dimensional mapping was carried out, and the sequence and place of measurements were developed. As a result, the level of soil compaction at different penetration depths and resistance to root growth was determined. It has been established that with constant traditional reverse tillage, the soil at a depth of more than 10 cm is sufficiently compacted. At a depth of 15 cm, a strong compaction of the soil is observed, which indicates its physical and hydrological degradation.

Impact of MHT9002HV Tracked Harvester on Forest Soil after Logging in Steeply Sloping Terrain

The article presents the results of measurements regarding the impact of the MHT9002HV tracked harvester on surface deformations and changing the physical parameters of the soil of three operational trails. The measurements were made in the terrain with a longitudinal slope of up to 14.9° (33.2%) and a transverse slope of up to 8.8° (17.9%). Spruce deadwood trees in mountain forest habitats were harvested. Static Eijkelkamp Penetrologger 0615SA and dynamic own design penetrometer were used to measure penetration resistance, soil samples were taken to determine bulk density, moisture content, and ground deformations on the trails were measured with a laser profilometer. A statistically significant increase in soil penetration resistance measured with penetrometers occurred for trails in the left rut at a depth of 16–20 cm. The change in the bulk density and moisture content proved statistically insignificant. The maximum ground deformation on the trails reached an average of 5.9 cm. The selection of a machine with low unit pressures (33 kPa), under the given favorable atmospheric conditions (there was a high temperature reaching 35 °C), with low soil moisture, protective organic layer of high thickness, and post-limbing residues, was optimal. The comparison of the results of the compactness measurements made with different penetrometers shows that the values obtained for the static penetrometer 0615SA are lower than those of the dynamic penetrometer of our own design. This is due to the lack of registration of high compactness in the memory of the 0615SA device. In the case of the impact penetrometer measurement, this problem does not occur, however, the presented solution does not allow performing a large number of measurements, and data processing in the case of such a simple solution is tedious. There is a need to develop a new penetrometer useful for determining soil compaction under similar difficult measurement conditions.

Soil and Residual Stand Disturbances after Harvesting in Close-to-Nature Managed Forests

Close-to-nature forestry is a viable option to manage forests that are resilient to the challenges presented by climate change. The new silvicultural schemes necessitate adapting the operational side, posing challenges to productivity and the environmental effects of harvesting machinery and technologies. This study focused on analysing the disturbance of residual stands and forest soils in stands that were being restructured into multistorey, close-to-nature managed ones using low-impact forest harvesting technologies. Measurements were performed in four stands after logging, divided into 30 sample plots with dimensions of 20 × 20 m. Within the plots, the disturbance of the residual stands and changes to the soil parameters, such as the soil bulk density (g·cm−3) and soil penetration resistance (MPa), were measured. The results showed that the intensity of the residual stand disturbance reached between 13% and 23% and was not significantly (p > 0.05) affected by the intensity of the performed harvesting operations. The mean size of the wounds was between 38.99 and 233.05 cm2, and wounds were most frequently in the size category of 11–50 cm2. Regarding soil disturbance, Spearman’s correlation showed a significant relationship (p ˂ 0.05) between the longitudinal slope and soil bulk density in the rut of the trail. The relative increase in BD showed that the largest increase occurred between the stand (undisturbed) and rut locations (12.5% to 24.77%). Penetration resistance measurements were affected by low moisture content and high coarse fragment content. Subsequently, Spearman’s correlation did not show (p > 0.05) a relationship between the soil bulk density and penetration resistance. Therefore, we can conclude that, from an environmental perspective, the proposed technologies are viable options for foresters who manage close-to-nature forests, and there was less disturbance of residual stands and forest soil caused by harvesting machinery.

Impact of spatial distribution on the sensory properties of multiphase 3D-printed food configurations

The rise of 3D-printing technology is opening up new possibilities for arranging two or more sensorily distinct phases in a specific manner, and thus potentially creating new sensory experiences. Particularly interesting is the spatial configuration of multiple phases for adjusting flavor and texture perception without changing the overall composition, as such configuration would represent a step towards individualization. In the present study, different 3D configurations of two rheologically and texturally very distinct phases were investigated as to their effect on mechanical properties and sensory perception. Chocolate and cream cheese masses were arranged three-dimensionally (cube-in-cube; layered) by additive manufacturing and characterized by measuring penetration resistance as well as by hedonic, descriptive, and temporal dominance of sensation (TDS) methodologies. By comparing samples with identical phase ratios, three characteristic texture profiles could be generated. How much the samples were liked depended significantly on perceived mouthfeel/texture and product hardness. The mouthfeel was in turn determined by the 3D configuration of the phases. TDS characterization showed either two or three dominance areas of one of the phases, depending on whether chocolate or cream cheese was perceived initially. While the dominance time of chocolate increased with increasing chocolate fraction in samples with chocolate as the external phase, the dominance time of cream cheese in samples with cream cheese as the external phase hardly changed with increasing phase fraction. This was mainly attributed to the very different rheological phase properties of cream cheese and chocolate. Based on the TDS evolution at the later stages of consumption that is rather independent of the initial configuration, the renewal of the relevant interface in the oral cavity was mainly determined by the mixing kinetics of both phases, and secondarily by what phase was perceived to be dominant before a phase dominance change took place. This study shows that in defining the 3D configuration of phases with differing rheological properties, there is considerable potential for adjusting the sensory properties. This is a step towards broader coverage of consumer needs through 3D product design without the need for formulation adjustments.

Assessing Subsoil Conditions with an ASABE Conform Vertical Penetrometer-Development and Evaluation.

Soil is the habitat for soil organisms and associated soil physical and chemical processes. The subsoil is a large reserve of water and nutrients. Soil and subsoil are thus significantly involved in the yield capacity of a site and its resilience in the case of unfavorable weather conditions. Subsoil can also retain water in drought phases and stores carbon. In times of climate change and scarcity of resources, many scientific activities involve subsoil and require sensors to assess subsoil conditions and properties. An electrically driven penetrometer with an integrated soil water content sensor could be an appropriate tool for such applications; however, such a subsoil measurement tool does not exist. One major reason for this is that, when penetrating compacted subsoil, high penetration forces (including friction) act on the penetrating thin rod (diameter 1 cm). The development of a tractor-mounted subsoil penetrometer for depths up to 2 m is described in this study. An ASABE standard cone is implemented, which can access heavy compacted layers. The rod, which includes wires for embedding an FDI moisture sensor in the cone tip, is covered by a protection tube. The penetration resistance measurement can be performed without being influenced by shaft friction. The rod, along with the sensor, is implemented in a tower that can be shifted laterally and can take probes in a single line without moving the tractor. To confirm the quality of the developed subsoil penetrometer, a suitable evaluation method is presented. Typical arable soil (loamy silt) was filled in boxes and compacted homogeneously using a hydraulic stamp so that different setups of the penetrometer could be compared and evaluated. The evaluation concludes that the distance between the free cone tip and the protection shaft should be at least 10 cm to measure the penetration resistance of soil without being influenced by the protection tube. Furthermore, the developed penetrometer has sufficient stability and precision for accessing subsoil. In field trials, the subsoil penetrometer was compared with a standard penetrometer and has proved its suitability.

Response to soil compaction of the electrical resistivity tomography, induced polarisation, and electromagnetic induction methods: a case study in Belgium

Context Soil compaction acts at different scales and is challenging to measure on field scales. Aims To evaluate soil compaction under a controlled traffic experiment, using three different geophysical methods. Methods Electrical Resistivity Tomography (ERT), Electromagnetic Induction (EMI), and Induced Polarisation (IP) were selected to map soil compaction. Two different ERT arrays and EMI geometries were selected with different spacings. The influences of configuration, electrode spacing, and the Depth of Investigation Index (DOI) were evaluated. Soil physical properties were measured in the Laboratory and in the field. Error models were developed to assess the accuracy of the ERT profiles and later correlated with EMI and soil physical results. Key results Penetration resistance measurements identified a compacted layer at 25 to 35 cm depth with a maximum value of 5 MPa under fixed tracks and bulk density of 1.52 Mg m−3, while lowest values were 1.4 MPa and 1.36 Mg m−3. The dipole–dipole (DD) 10 cm array was more accurate towards both soil properties and locating the zones of high resistivity. The IP method identified chargeability anomalies at the same depth as the resistivity anomalies, possibly indicating a similar origin. The EMI test was less successful in accurately determining the locations of the conductive areas. Conclusions A clear relationship between the absolute value of the resistivity/conductivity signals with the level of compaction was not found, yet patterns of lateral variations in resistivity were identified. Implications Further studies are needed to establish the concrete relationship between soil compaction and geophysical signals.

Technological Advances in Soil Penetration Resistance Measurement and Prediction Algorithms

Soil compaction is one of the most harmful elements affecting soil structure, limiting plant growth and agricultural productivity. It is crucial to assess the degree of soil penetration resistance to discover solutions to the harmful consequences of compaction. In order to obtain the appropriate value, using soil cone penetration requires time and labor-intensive measurements. Currently, satellite technologies, electronic measurement control systems, and computer software help to measure soil penetration resistance quickly and easily within the precision agriculture applications approach. The quantitative relationships between soil properties and the factors affecting their diversity contribute to digital soil mapping. Digital soil maps use machine learning algorithms to determine the above relationship. Algorithms include multiple linear regression (MLR), k-nearest neighbors (KNN), support vector regression (SVR), cubist, random forest (RF), and artificial neural networks (ANN). Machine learning made it possible to predict soil penetration resistance from huge sets of environmental data obtained from onboard sensors on satellites and other sources to produce digital soil maps based on classification and slope, but whose output must be verified if they are to be trusted. This review presents soil penetration resistance measurement systems, new technological developments in measurement systems, and the contribution of precision agriculture techniques and machine learning algorithms to soil penetration resistance measurement and prediction.

Invasion in the riparian zone: What is the effect of Pteridium arachnoideum on topsoil permeability?

Pteridium arachnoideum is a cosmopolitan, allelopathic, pervasive species which is expanding its occurrence in many regions of the tropics. Yet, the ecohydrological effects of such colonization is virtually unknown especially when it occurs in riparian zones which are expected to perform many important ecosystem services. The objective of the present study was to evaluate the influence of Pteridium colonization on topsoil permeability in riparian zones. To do that, we selected two similar riparian zones: (i) dominated by Pteridium arachnoideum and (ii) under tropical forest. We performed infiltration, water repellency (dry and wet season) and penetration resistance measurements to evaluate soil permeability. The infiltration capacity was significantly lower in Pteridium compared to riparian forest. We attribute this reduction to the significant increase in both water repellency in the dry season and soil penetration resistance in the soil under Pteridium. Water repellency, though still present in the wet season in both riparian zones, had no significant difference. Our results show that, despite the loss of biodiversity with Pteridium invasion, water repellency has a clear reduction in the wet season which likely benefits infiltration. Thus, basic hydrological ecosystem services can probably still be provided by such invaded riparian zones.

Practical Implications of the Availability of Multiple Measurements to Classify Agricultural Soil Compaction: A Case-Study in The Netherlands

Soil compaction is a severe threat to agricultural productivity, as it can lead to yield losses ranging from 5% to 40%. Quantification of the state of compaction can help farmers and land managers to determine the optimal management to avoid these losses. Bulk density is often used as an indicator for compaction. It is a costly and time-consuming measurement, making it less suitable for farmers and land managers. Alternatively, measurements of penetration resistance can be used. These measurements are cheaper and quicker but are prone to uncertainty due to the existence of a wide array of thresholds. Classifications using either measurement may provide different outcomes when used in the same location, as they approximate soil compaction using different mechanisms. In this research, we assessed the level of agreement between soil compaction classifications using bulk density and penetration resistance for an agricultural field in Flevoland, the Netherlands. Additionally, we assessed the possible financial implications of misclassification. Balanced accuracy results indicate that most thresholds from the literature show around 70% agreement between both methods, with a maximum level of agreement of 76% at 1.8 and 1.9 MPa. The expected cost of misclassification shows a dip between 1.0 and 3.0 MPa, with an effect of crop value on the shape of the cost function. Although these results are specific to our study area, we believe they show that there is a substantial effect of the choice of measurement on the outcome of soil compaction studies.

Soil Compaction in Harvesting Operations of Phalaris arundinacea L.

Tillage and harvesting operations of perennial forage crops have problems with soil compaction. The effects of this phenomenon are soil deterioration with reduced crop performance and yield. This study aims to assess soil disturbance by measuring the level of compaction caused by the harvesting operations of Phalaris arundinacea L. P. arundinacea is a species that lends itself to biomass production and phytoremediation of contaminated soils; it adapts to difficult soil conditions, outperforming other species in terms of ease of planting, cost, maturity time, yield, and contamination levels. The crop was sown in three plots of the experimental teaching farm of the University of Tuscia, Viterbo, Italy. Following a detailed analysis of the chemical–physical characteristics of the soil, minimum tillage was chosen in order to concentrate on harvesting operations, which were carried out with a disc mower coupled to a tractor. This was followed by penetration resistance and soil moisture measurements to verify the incidence of the operations and the effect of the type of crop on compaction. On the study site, measurements were taken at points that the wheels of the tractor had gone over and at points that they had not. The soil analysis results indicate different chemical–physical characteristics between the two areas, the texture being frankly sandy to clayey. Penetration resistance measurements indicated differences for the first 20 cm between the part that was covered by the tractor’s tyres and the part that was left touched but also between the three plots. Moisture influenced penetration resistance. This study provides an evaluation of the first data obtained from a project that will last four years and which will explore the dynamics between soil, cultivation, and harvesting operations, giving a fundamental basis for further investigation of further harvesting operations and soil characteristics, which are crucial for planning and managing crops and reducing impacts on the soil in order to preserve it.

Soil Penetration Resistance Influenced by Eucalypt Straw Management under Mechanized Harvesting

This study aimed to evaluate the impacts of mechanized harvesting and soil tillage on soil penetration resistance (PR), influenced by the eucalypt straw management under sandy clay Oxisol in Southern Brazil. The study was conducted in a eucalyptus production area under Oxisol in Paraná State, Brazil. The treatments consisted of two harvesting systems: harvester + forwarder (HF) and feller + skidder (FS) both applied in areas under coppicing and stand renewal eucalypt cultivation systems. For stand renewal areas, eucalypt straw was managed on the soil surface at levels of 100, 50, and 0% before soil tillage. PR and soil moisture measurements were made in points distributed in regular grid for all treatments. This grid also was used to evaluate the geospatial behavior of PR in the stand renewal areas. During the measuring of PR, the averages (± confidence interval) of soil moisture up to 0–0.60 m depth were 0.20 ± 0.01 and 0.24 ± 0.01 in coppicing and stand renewal areas, respectively. In areas under coppicing, the PR mean ± confidence interval at 0–0.05 m layer in HF (1.28 ± 0.24 MPa) was lower than in FS treatment (2.11 ± 0.44 MPa). However, the PR values were similar between treatments in stand renewal areas, regardless of the forest straw level on the soil surface. For both harvesting systems, there was a lack of spatial dependence of PR up to 0.40 m soil depth, indicating some physical and mechanical homogenization induced by the soil tillage in the layer. Eucalypt straw contributed to mitigating effects of harvest traffic on PR level in coppicing forest systems. However, different levels of eucalypt straw managed before soil tillage did not influence PR levels in stand renewal forest systems.

Within-field spatial variations in subsoil bulk density related to crop yield and potential CO2 and N2O emissions

Subsoil compaction is an increasing problem in modern agriculture, but is not easily recognized in practice, also because of possible within-field spatial variations. This paper addresses the question of how within-field spatial variations in soil bulk density and other soil characteristics relate to within-field spatial variations in crop yield and potential CO2 and N2O emissions from soil. Four fields (5 to 20 ha each) were selected at the suggestion of crop farmers, and sampled using a random soil sampling design (100 samples per field). Undisturbed soil samples were taken at depth of 5–10, 30–35, and 50–55 cm and soil bulk density and potential CO2 and N2O emissions measured under controlled conditions. At each sampling point, also top soil (0–20 cm) samples were taken for determination of pH, texture, SOM, and (micro)nutrients, and soil penetration resistance measurements and visual assessments of soil structure were made. Wheat yields were recorded with harvesters equipped with GPS and yield recorders.Mean soil bulk density in the sub-soil (30–35 cm) ranged between fields from 1.36 ± 0.08 to 1.60 ± 0.11 g cm−3. Mean wheat yields ranged between fields and years from 7.6 ± 0.6 and 11.3 ± 2.4 Mg ha−1. Semi-variogram analyses showed that crop yields and soil properties were mostly spatially dependent; nugget-to-sill ratios were < 25% with ranges of 137 to 773 m. The ratio of CO2 emissions to N2O emissions was negatively related to soil bulk density, especially following N application.In conclusion, within-field spatial variations in subsoil bulk density were successfully related to spatial variations in crop yield and potential CO2 and N2O emissions. The ratio of CO2 emissions to N2O emissions had a much greater response to spatial variations in soil bulk density than wheat yield. Our study suggests that N2O emission factors may depend on (sub)soil bulk density.

Cover Crop Grazing Effects on Soil Compaction Indicators in Western and Central Kansas

Grazing cover crops (CCs) on no-till (NT) croplands in western and central Kansas could increase the profitability of crop production in these water-limited environments. However, little information exists about potential soil compaction associated with grazing CCs in these cropping systems. From 2019 to 2021, two studies investigated the effects of grazing CCs on soil bulk density and penetration resistance in NT cropping systems. At the Kansas State University HB Ranch near Brownell, KS, CCs grazed with yearling heifers were compared to ungrazed CCs and fallow under NT or occasional tillage (OT). In another study, CCs grazed with yearlings or cow-calf pairs were compared to ungrazed CCs across seven site-years on producer fields in western Kansas (Alexander and Hays) and central Kansas (Marquette 1 and 2). Soil bulk density and penetration resistance measurements were made at the time of subsequent grain crop planting following CCs. At Brownell, CC management, tillage, and their interaction had no significant effect (P > 0.05) on soil bulk density. Across years, bulk densities with fallow, ungrazed CCs, and grazed CCs were 1.11, 1.15, and 1.15 g/cm3at the 0- to 2-inch soil depth, respectively. Soil bulk densities with NT and OT were 1.14 and 1.14 g/cm3 at the 0- to 2-inch soil depth, respectively. Similarly, CC grazing had no significant effect on soil bulk density and penetration resistance across the seven on-farm sites-years. At the western Kansas locations, soil bulk density averaged 1.23 g/cm3 at the 0- to 2-inch soil depth with grazed or ungrazed CCs. At the central Kansas locations, soil bulk density averaged 1.31 and 1.36 g/cm3 at the 0- to 2-inch soil depth for grazed and ungrazed CCs, respectively. Bulk density measured at 2- to 6-inch depth was not different between grazed and ungrazed CC in either study. At Alexander, penetration resistance was 0.52 and 0.52 MPa with grazed and ungrazed CCs, respectively. Penetration resistance was 0.36 and 0.34 MPa with grazed and ungrazed CCs, respectively, at Marquette 1. Results showed that grazing CCs never increased soil bulk density or penetration resistance compared to ungrazed CCs. Based on these findings, grazing CCs on NT fields can be a strategy for producers to balance profitability and soil health.

Characterization of the soil compaction based on the mapping of the apparent electrical conductivity

Based on the measurement of soil penetration resistance (PR), it is possible to identify compacted soil layers, where root growth may be harmed, affecting crop development and yield. The objective of this work was to analyze the use of management zones (MZ), delimited on the basis of mapping of the spatial variability of the soil apparent electrical conductivity (ECa), in the differentiation of soil compaction levels. The work was carried out in a 25.8-ha no-tillage area, cultivated under a center pivot. The ECa was measured under two soil moisture conditions (13.7 and 16.45%), using the Terram® equipment. Soil penetration resistance (PR) was measured using the SoloStar PLG5500 penetrograph. Based on the spatial variability ECa mapping, management zones (2, 3, and 4 zones) were delimited. The mean PR values ??of each MZ were compared by the t-test of means. It was possible to differentiate mean values ??of penetration resistance (PR), which vary from 0.9 to 2.10 MPa, from the characterization of management classes generated on the basis of the ECa spatial variability. The highest stratification of PR values ??was obtained as a function of sampling directed at delimited management zones when the soil had lower moisture content (13.7%). The highest mean PR values ??were obtained for the split of the ECa map into at least three classes. It was identified that for the study area there is no need to perform any mechanical decompaction operation.

A hybrid method for characterizing tillage-induced soil physical quality at the profile scale with fine spatial details

Robust methods are needed to assess tillage-induced changes in the physical quality of agricultural soils. Most soil physical quality (SPQ) evaluation procedures are based on the analysis of a limited number of soil cores randomly sampled in the soil profile. Such procedures likely fail to properly capture the spatial patterns in soil structure induced by tillage implements and vehicle traffic, resulting in a misleading SPQ diagnosis. We propose a hybrid method that couples high-resolution soil penetration resistance measurements with soil core sampling to derive high-resolution data grids of SPQ indicators encompassing the soil profile structural heterogeneity. The method builds on strong experimental relationships between soil penetration resistance and bulk density, and between bulk density and the soil hydraulic properties. We tested our method on a silt-loam soil with three tillage treatments (moldboard plowing, deep loosening with a tine cultivator, and minimum tillage), each including a zone impacted by the wheel traffic. The results allow visualization and analysis of the effect of tillage treatments and vehicle traffic on the soil SPQ indicators with a high level of spatial detail. The proposed methodology can be used to compare various soil management techniques or to monitor the temporal evolution of SPQ. As such, it can be a valuable tool to guide agricultural soil management. Furthermore, the generated high-resolution soil physical parameter grids could be used to parameterize numerical hydrodynamic models and estimate water and solute fluxes with distributed parameters representing the actual soil profile heterogeneity.