Mean Penetration Resistance Research Articles

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.

Penetration Resistance of Laacher See-tephra Andosols—Evaluating Rooting Conditions of Undisturbed and Excavated Forest Soils in SW-Germany

This study discusses penetration resistance (PR) of forested Pumice-Andosol sites. PR, a key soil property influencing root growth and elongation, exerts a substantial influence on ecological site quality and tree growth. Andosols were expected to show low PR because of their unique characteristics (low bulk density, loose soil matrix). Five sites, two undisturbed and three backfilled, were sampled. The latter result from pumice excavation and were examined to quantify potential PR alterations in the aftermath of backfilling and pumice removal. Penetrologger sampling on undisturbed sites showed mean PR not exceeding 3 MPa, a literature-based, critical threshold restricting root growth, in the upper 0.80 m, indicating conditions fostering tree rooting. Backfilled sites mostly exhibited increased (> 3 MPa) PR, leading to rooting restrictions even beginning at −0.21 m. Deviations from undisturbed soils range from −15.6 to +109.3% depending on depth and age of the backfilled site. Furthermore, GIS-based data interpolation helped to identify spatial PR patterns and allowed a direct comparison before/after backfilling at one site. Statistical analysis revealed significantly altered PR after backfilling, while a concluding ANOVA provided at least significant governing factors (depth, area, clay + silt content, soil organic matter), albeit with only small effect sizes.

Influence of particle size on vertical plate penetration into dense cohesionless granular materials (large-scale DEM simulation using real particle size)

The influence of the particle size on the vertical plate penetration into dense cohesionless granular materials was numerically investigated. Simulations were performed in quasi-two-dimensional conditions by changing the mean particle diameters d50 but maintaining the plate thickness B from B/d50 = 63–2.6. The initial bulk packing fraction was kept high, irrespective of the particle size. In the smallest particle size case (B/d50 = 63), the size ratio reached almost the same level as that in the laboratory experiments using natural sand particles. The results demonstrated that the mean penetration resistance force acting on the plate tip surface increases with a decrease of B/d50, while the tangential force acting on the side surfaces does not change with B/d50. Tip resistances increase linearly with the penetration depth, while the tangential resistances increase with the square of the depth regardless of B/d50. The behavior of the resistance fluctuations changes qualitatively between B/d50 = 31 and 21. For all cases, we confirmed the formation of a wedge-shaped flow with a high forward velocity in front of the plate tip. The wedge flow width was larger than the plate thickness by almost a mean particle diameter, and was responsible for the increase in the mean resistance depending on the particle size. For the large B/d50 cases only, the resistance exhibited quasi-periodic fluctuations, which was attributable to the intermittent nucleation and disappearance of the shear bands. Moreover, we investigated the dependence of B/d50 on the band evolutions by analyzing the band thickness.Graphic abstractThe influence of the particle size on the vertical plate penetration into dense cohesionless granular materials was numerically investigated using DEM. Simulations were performed in quasi-two-dimensional conditions by changing the median particle diameters d50 but maintaining the plate thickness B. The initial bulk packing fraction was kept high, irrespective of the particle size. Upper and lower figures show the result of small (B/d50 = 63) and large particle size case (B/d50 = 21), respectively. In the small particle size case (B/d50 = 63), the size ratio reached almost the same level as that in the laboratory and the dynamics of 35.5 million particles was considered. Right and left figures illustrate instantaneous shear strain rate and local packing fraction distributions, respectively. Large qualitative change in the granular behaviors as well as penetration resistance was observed between B/d50 = 31 and 21. The intermittent nucleation and disappearance of the shear bands were clearly observed only for large B/d50 cases.

The cone index is a weak predictor of soil disturbance on forest soils of the Western Carpathians

ABSTRACTSoil compaction is one of the primary causes of soil degradation. Predicting the soil disturbance by assessing the cone index of the soil is becoming popular, due to the simplicity of measuring it with a cone penetrometer. This paper is focused on assessing, whether the cone index is a suitable predictor of soil compaction on cambisols, luvisols, and rendzic leptosols. Overall, we measured penetration resistance, bulk density, moisture content, and rut depth on 250 locations in forests of the Western Carpatians. The mean penetration resistance of the undisturbed soil was 4.33 and 4.41 MPa in the ruts of the skid trails; the mean cone index of the undisturbed soil was 5.46 MPa; the mean bulk density of undisturbed soil was 0.95 g cm−3; the mean moisture content of the undisturbed soil was 24%; the mean rut depth was 6 cm, and the maximal rut depth was 38 cm. Spearman’s correlation analysis showed that the relationship between the mean rut depth and the cone index was statistically insignificant, and the relationship between the maximal rut depth and the cone index was, though significant, weak (R = −0.20).

Borçka Barajı Rezervuarında Yeni Oluşmuş Bir Sediment Birikim Sahasındaki Penetrasyon Direnç Değerlerinin Uzaysal Dağılımı

This study was conducted to analyze vertical and horizontal spatial variability of penetration resistance (PR) in recently deposited sediments at Borcka Dam reservoir. Ninety-one grids with 50 m by 10 m were located and PR was measured to a depth 80 cm by 10 cm increment (8 layers) within each grid. Spatial variation of PR was assessed by geostatistical techniques in all 8 layers. Semivariograms of PR were constructed for all the layers and corresponding kriging maps were built. The PR values were greater in surface layer (0-10 cm) and gradually decreased by depth. Mean PR was greatest (0.747 MPa) in surface layer and lowest (0.413 MPa) in 61-70 cm (layer 7). Results from exploratory statistics and geostatistical analyses showed that the PR values were more variable in surface layer compared to those in deeper layers due to that the surface layer was drier at the sampling and that affected by environmental factors in a greater extent. All the studied layers exhibited differences in spatial variation of PR as sill, nugget, and range values of corresponding semivariograms and kriging-predicted surface maps showed. The shortest geostatistical range (40.8 m) occurred of surface layer while longest (173.3 m) occurred for second layer (11-20 cm). The nugget effect was greatest (44%) in third layer (21-30 cm) while lowest (13%) in the surface layer. The same study may be repeated with more variables to understand mechanisms behind development and extent of spatial variation in these newly deposited sediments.

Spatial variability of soil penetration resistance in an alluvial delta plain under different land uses in middle Black Sea Region of Turkey

ABSTRACTThe aim of this study was to analyse the soil compaction and its spatial variability on an alluvial plain in Kızılırmak River Delta in Turkey, which is an important agricultural area where vegetable, rice, cereals and other crops have been grown under conventional tillage and irrigation over a long period. Penetration resistance (PR) was measured at 5 cm depth intervals between 0 and 40 cm soil depth, and gravimetric water content (GWC), field capacity (FC) and texture were determined for 0–20 cm and 20–40 cm. Penetration resistance values in some parts of the area were higher than the critical value for root growth limitation, the mean PR values at all depths were considerably lower than the critical value despite a relative increase in PR with soil depth. The areas with values greater than 3.0 MPa, except for 0–5 cm, were generally located in the fields with high sand content, especially near the Kızılırmak River. In contrast, for 0–5 cm, the areas with PR greater than 3.0 MPa, which is the value accepted for root growth limitation, were usually located in the west and northwest of the study area and had a high clay content.

Sampling plan for using a motorized penetrometer in soil compaction evaluation

ABSTRACT This study aimed to estimate the size of blocks of observations of resistance to penetration, obtained by a motorized digital penetrometer, and the number of blocks with semi-amplitude of the confidence interval between 5 and 20% of the mean penetration resistance, for different soil depth ranges and cone diameters. Data were collected in two contrasting plots of a crop-livestock integration experiment, located in Abelardo Luz, SC, Brazil. Ten blocks were delimited and the resistance to penetration was determined in 20 points spaced by 20 cm, using a motorized digital soil penetrometer. To estimate the mean of resistance to penetration, 12 blocks of four points per experimental plot should be used for a semi-amplitude of the confidence interval equal to 10% of the mean (1 - p = 0.95). Twenty random points may be sampled to estimate mean of penetration resistance for a semiamplitude confidence interval of 10% of the man (1 - p = 0.95). The sample size for the layer of 0-10 cm is larger than in the deeper layers (0-20, 0-30 and 0-40 cm) and smaller for cones with larger diameter.

Impact of Residential Prairie Gardens on the Physical Properties of Urban Soil in Madison, Wisconsin.

Prairie gardens have become a common addition to residential communities in the midwestern United States because prairie vegetation is native to the region, requires fewer resources to maintain than turfgrass, and has been promoted to help remediate urban soil. Although prairie systems typically have deeper and more diverse root systems than traditional turfgrass, no one has tested the effect of this vegetation type on the physical properties of urban soil. We hypothesized that residential prairie gardens would yield lower soil bulk density (BD), lower penetration resistance (PR), greater soil organic matter (SOM), and greater saturated hydraulic conductivity () compared with turfgrass lawns. To test this hypothesis, we examined 12 residential properties in Madison, WI, where homeowners had established a prairie garden within their turfgrass lawn. Despite a consistent trend in the difference between vegetation types, no significant main effects were found (i.e., a difference between vegetation types when averaged over depth) for any of the four soil properties measured in this study. Differences were found with depth and depended on a significant interaction with vegetation type. At the surface depth (0-0.15 m), soil beneath prairie gardens had 10% lower mean BD, 15% lower mean PR, 25% greater level of SOM, and 33% greater compared with soil beneath the adjacent lawns. These differences were not detected at deeper sampling intervals of 0.15 to 0.30 m and 0.30 to 0.45 m. Although not statistically significant, the consistent trend and direction among soil variables suggest that residential prairie gardens had changed the surface soil at a rate that marginally outpaced turfgrass and calls for controlled experiments to identify the mechanisms that might enhance these trends.

Compared performance of penetrometers and effect of soil water content on penetration resistance measurements

Modern agriculture techniques have a great impact on crops and soil quality, especially by the increased machinery traffic and weight. Several devices have been developed for determining soil properties in the field, aimed at managing compacted areas. Penetrometry is a widely used technique; however, there are several types of penetrometers, which have different action modes that can affect the soil resistance measurement. The objective of this study was to compare the functionality of two penetrometry methods (manual and automated mode) in the field identification of compacted, highly mechanized sugarcane areas, considering the influence of soil water volumetric content (θ) on soil penetration resistance (PR). Three sugarcane fields on a Rhodic Eutrudrox were chosen, under a sequence of harvest systems: one manual harvest (1ManH), one mechanized harvest (1MH) and three mechanized harvests (3MH). The different degrees of mechanization were associated to cumulative compaction processes. An electronic penetrometer was used on PR measurements, so that the rod was introduced into the soil by hand (Manual) and by an electromechanical motor (Auto). The θ was measured in the field with a soil moisture sensor. Results showed an effect of θ on PR measurements and that regression models must be used to correct data before comparing harvesting systems. The rod introduction modes resulted in different mean PR values, where the "Manual" overestimated PR compared to the "Auto" mode at low θ.

A note on the deep penetration of projectiles into concrete

A simple equation is presented herein to predict the deep penetration of concrete targets struck normally by projectiles within a unified framework. The effects of various parameters such as nose shape, impact velocity and unconfined compressive strength are considered in the formulation by the mean resistive pressure which consists of two parts, namely, cohesive static resistive pressure due to the elastic–plastic deformations and the dynamic resistive pressure arising from velocity effects. It is demonstrated that the present equation is in good agreement with available experimental data for the penetration of concrete targets. It is also demonstrated that the mean penetration resistance of concrete materials with unconfined compressive strengths ranging from 75 MPa to 150 MPa is almost the same which may have serious implication for the design of concrete targets against projectile penetration.

Application of an electronic micropenetrometer to assess mechanical stability of biological soil crusts

AbstractAn in situ determination of biological soil‐crust stability was carried out in two study sites along a sharp rainfall gradient. Penetration resistance (PR) of the crusts was measured using a newly developed light‐weight needle‐type electronic micropenetrometer. The depth‐related PR data revealed two sections possessing different structures and stability. The topcrust (0–2 mm) had significantly higher amounts of N, organic C, carbonates, and salts as compared to the underlain subcrust. The mean PR of the topcrust was 0.68 MPa for the southern study site, Nizzana‐South (≈ 100 mm annual rainfall), and it increased significantly for the northern study site, Nizzana‐69 (≈ 170 mm annual rainfall), with a mean of 1.11 MPa. A subcrust (2–30 mm) was identified that was characterized by a high amount of carbonates and a PR > 2 MPa. The electronic micropenetrometer system is a promising device for identifying areas of changing crust stability in relation to biological soil‐crust properties. The overall stability of biological soil crusts depends on the topcrust and subcrust structure. This structure is linked to abiotic and biotic factors and likely in relation to the amount of annual precipitation.

Experimental and numerical investigation of the sintering rate of snow

AbstractSintering rates in snow were investigated by measuring changes in penetration resistance with time and by using a numerical snow metamorphism model. Periodic Snow Micro Penetrometer (SMP) measurements were performed on uniform snow samples covering a wide range of densities. The mean penetration resistance of snow increased with time according to a power law with an average exponent of 0.18. Simulated changes in the bond-to-grain ratio for simplified spherical ice grains followed a power law with an average exponent of 0.18, showing that the mean penetration resistance, as measured with the SMP, closely relates to bond-to-grain ratio in snow. For lower-density snow samples, consisting mostly of dendritic snow morphologies, the measured increase in penetration resistance was lower. This is likely the result of two competing processes: (1) strengthening of the snow sample due to the creation and growth of bonds and (2) weakening of the snow sample due to the formation of unbonded small rounded particles at the expense of larger dendritic forms. On the other hand, the rate of increase in penetration resistance for snow samples consisting of closely packed depth hoar was similar to that of rounded grains.

A survey on the soil penetration resistance and soil moisture content in field experiments

Various forms of physical soil degradation, including soil compaction, have been widely investigated both in Hungary and abroad. Soil compaction is a world-scale problem, which may be triggered by both natural and artificial factors and may adversely influence the effectiveness of crop production. In the long run this unfavourable change in the physical condition of the soil may result in extra expenses, higher energy consumption and excessive environmental damage. The effect of conventional tillage on the physical condition of the soil was assessed on six farms for three years in the framework of field experiments. In this study the physical condition of the soil was examined in terms of soil penetration resistance and moisture content. Significant differences between the experiments were revealed when penetration resistance (PR) was examinated at a depth of 20–30 cm, but not at other depths. In 2004 the mean PR values exceeded 3 MPa in experiments A, B and E. In 2005 significant differences were observed between the experiments at a depth of 30–40 cm, but no adverse compaction was detected at any depth in any of the experiments. In 2006 significant differences were observed between the experiments at depths of 0–10 cm and 10–20 cm, though even in that year no adverse soil compaction was detected. In the first year significant differences in soil moisture content were revealed at depths of 10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm, and in 2005 at depths of 20–30 cm and 30–40 cm. In 2006 no significant differences were found between the experiments at any depth. The highest soil moisture contents were recorded in all the experiments at a depth of 30–40 cm. All in all, the results of both penetration resistance and moisture content were indicative of favourable soil conditions. During the period investigated adversely compact layers that would hamper moisture transport were not found in any of the experiments.

Changes in distribution patterns of soil penetration resistance within a silage-corn field following the use of heavy harvesting equipments

Soil compaction caused by heavy wheeling reduces water infiltration, root development, and yield, and increases bulk density and soil strength. The objective of this study was to determine changes in spatial variability patterns of soil penetration resistance before and after using the silage machine in a corn-growing field. Soil penetration resistance was measured in a 100 × 400 m field with 10 m intervals just before and after harvesting. Measurements were taken from the 20 cm top layer on rows and inter-rows throughout each transect. The mean penetration resistance of 1353 measurements before and after harvesting was 2097 and 3116 kPa, respectively. Average bulk density within the field increased from 1.14 g cm-3 to 1.46 g cm^{-3}, but wet aggregate stability decreased from 33.4% to 17.9% following harvesting. Punctual kriging analysis was performed to prepare distribution maps of soil penetration resistance with 1 m intervals within the field. The patterns of variation in soil penetration resistance following harvesting showed remarkable differences compared to pre-harvesting.

Site classification of Turkish national strong-motion stations

Since 1973, the General Directorate of Disaster Affairs of Turkey has deployed several strong-motion accelerographs at selected sites. Within the framework of the project entitled Compilation of National Strong Ground Motion Database in Accordance with International Standards, site conditions were investigated within the upper 30-m depth by surface seismic and standard penetration tests. Preliminary characterization of the sites is made by making use of both geophysical and geotechnical criteria of NEHRP Provisions and Eurocode-8 site classification systems. The liquefaction susceptibility of those sites which comprise saturated cohesionless deposits is also determined. Mean shear-wave velocity, mean penetration resistance, site class, and liquefaction susceptibility of each site are tabulated. The Turkish strong-motion database supplemented by detailed information on site conditions is a valuable source of information particularly for those studies that put emphasis on the relationship between site conditions and strong-motion parameters.

Deformation of snow during a carved ski turn

Abstract Skiing sports have experienced a significant boost in the 1990s when the classical ski geometry was replaced by a deep side cut ski, the carving ski. The geometrical and mechanical characteristics of modern carving skis are adjusted to typical turn radii, such that the skis cut through the snow surface with minimized skidding. As a ski passes over the snow surface in a carved turn the inclined skis penetrate the snow surface until the contact area suffices to allow snow of a given resistive strength to support the load exerted by the ski. In this study we measured the mean resistance pressure the snow exerts to an inclined plate penetrating the snow surface as a function of penetration depth. The tests were carried out on several groomed ski pistes of different snow types. We found that the mean penetration resistance pressure for homogeneous snow increased linearly with the penetration depth. Hence, the snow resistance of different snow types can be characterized by the slope A and the offset pressure B of this linear function. For groomed, homogeneous snow pistes values of the coefficient A lie typically between 5 and 40 MPa m − 1 , values of the coefficient B lie typically between 0 and 400 kPa. Moreover, the slope A increases with increasing edging angle, but if the edging angle surpasses a threshold angle found between 30° and 45° the mean snow resistance pressure falls due to frequent shear fractures, by which the snow is pressed out of the indent. The overall trend in snow resistance curves can still be approximated by a linear function, but the slope A falls to values in between 2 and 20 MPa m − 1 . The offset pressure B strongly depends on surface characteristics of the snow, which often deviate from the subjacent snow due to exposure to the sun's radiation or to skier's traffic. If the snow surface is considerably softer than lower snow layers, then the offset pressure B of the overall snow resistance function may even be negative. This study provides the so far missing experimental data for models of the ski–snow interaction in carved turns.

Physical and mechanical properties of a clayey soil as affected by tillage systems for wheat growth

The effect of tillage systems on soil physical properties of a clayey soil was studied. Tillage systems consisting of conventional tillage I (CT1), conventional tillage II (CT2), reduced conventional tillage (RCT), reduced tillage (RT) and no tillage (NT) were carried out in autumn after harvest of sugar beet. Significant differences between tillage systems were recorded on the measured properties, apart from moisture content, at 15–30 cm soil layer. The CT1, CT2 and RCT systems resulted in similar penetration resistance and bulk density values below the 15 cm soil depth, while the RT and NT systems resulted in higher but similar values. The mean penetration resistance values were less than 1 MPa in the CT1, CT2 and RCT systems at the 0–15 cm depth, while they were 1.41, 1.84 MPa in RT and NT, respectively. The mean total porosity increased with tillage from 8.2 to 28% when compared with NT. The CT1, CT2 and RCT systems resulted in lower moisture content at the 0–15 cm depth. The lowest moisture content occurred in RCT (24.4%) and the highest in NT (30.9%), while it was 30.3% in RT system. The lowest and highest mean weight diameter values were reported for the RT (1.36 mm) and NT (2.37 mm) systems, respectively. The lowest wheat grain yield was obtained in NT (4.14) and the highest in CT1 (5.24 Mg ha−1). A significant difference occurred between only NT and the other systems. When both grain yield and advantages of reduced tillage are considered, the RT system is recommended.

Effects of deep ripping and organic matter amendments on Ap horizons of soil reconstructed after coal strip-mining

Deep ripping is a common management technique used to shatter dense subsurface soil horizons that limit percolation of water and penetration of roots. Most studies have concentrated on the effects of deep ripping on subsoils, with few examining the effects on surface soil horizons. A study was conducted on reclaimed fields (undisturbed soil Albic Luvisol) at the Highvale coal mine approximately 80 km west of Edmonton, Alberta, Canada, with objectives to evaluate the effect of deep ripping, with and without the use of organic matter amendments, on the physical and chemical properties of Ap horizons of reconstructed minesoils. Significant treatment effects were identified for particle size distribution (all fractions), plasticity index and the October mean penetration resistance (PR), but effects on bulk density, soil water content at the time of sampling, water retention characteristics and modulus of rupture were non-significant. Soil chemical properties significantly affected included pH, soluble Ca and Mg, exchangeable Na and K, exchangeable Ca:Na ratio and loss of ignition. Addition of subsoil to the Ap horizon as a result of deep ripping likely caused the changes. They are expected to make the seedbed more difficult to cultivate and manage unless specific management practices such as organic matter additions are adopted to overcome the detrimental changes in soil properties that have occurred. Key words: Manure, peat, reclamation, soil properties, subsoiling, surface horizon, tilth

Engineering Properties of Sewage Sludge in Trinidad

Abstract Some physical and engineering properties of five sewage sludges collected from different locations in Trinidad were measured in the laboratory. The properties assessed were dry bulk density, fibrosity, water content, solids content, the Atterberg limits, saturated hydraulic conductivity, density–water relations, penetration resistance, shear strength and compressibility. Air–dry bulk density of the sludges ranged from 0·37 to 0·83 Mg/m3while the solids content varied from 65·4 to 90·3%. Most of the parameter values differed according to the organic matter content of the sludges. The exception to this general trend was the sludge from Trincity. The sludges exhibited very high liquid limits ranging from 165% for the Valencia sludge with the highest organic matter content of 30·9% to 66% for the Santa Cruz sludge with the lowest organic matter content of 10·8%. Proctor compaction test results showed that mean compaction for 5, 15 and 25 Proctor compaction blows varied from 0·51 Mg/m3for Valencia to 1·19 Mg/m3for Santa Cruz sludge. Mean penetration resistance after compaction also varied from 1·70 MPa in the Valencia sludge to 4·05 MPa for the Santa Cruz sludge. Mean shear strength varied from 59·7 kPa in Valencia to 99·7 kPa in Santa Cruz sludge. The corresponding saturated hydraulic conductivity measured on compacted sewage sludges also varied from 16·6 to 0·11 cm/h for the Valencia and Santa Cruz sludge, respectively. The compressibility of the sludges defined in terms of a compression index increased from 0·50 for the Santa Cruz sludge to 1·02 for the Valencia sludge. Generally, the sewage sludges were found to display an engineering behaviour similar to mineral soils, differing only in the magnitudes of the measured parameters. The implications of the measured parameter values on the choice of method for use or disposal of these sewage sludges are discussed.

Soil bulk density, penetration resistance, and hydraulic conductivity under controlled traffic conditions

Adverse soil physical conditions that limit soil water infiltration, root development, and crop yield could develop when using a no-tillage system, especially in humid regions or for irrigated crops. This study determined the effects of tillage treatments and controlled traffic on soil bulk density ( BD), penetration resistance ( PR), hydraulic conductivity ( HC), water content, and organic matter concentration. Treatments were no-tillage with residues left standing (NT-ResSt) or shredded (NT-ResSh), and no-tillage after wheat and conventional tillage after sorghum (NT-CT). Determinations were made at traffic furrow, non-traffic furrow, and row positions after grain sorghum ( Sorghum bicolor (L.) Moench) harvest in 1992. The grain sorghum had been grown in rotation with winter wheat ( Triticum aestivum L.) under limited irrigation conditions on Pullman clay loam (Torrertic Paleustoll) at Bushland, Texas, from 1986 to 1992. Tillage treatments did not significantly ( P = 0.05) affect any determined variable. Mean PR was greates (1.23 MPa) in the traffic furrow, but sampling position did not affect BD. Differences in HC were significant ( P = 0.05) only due to sampling depth, but tended to be greater in row than in furrow positions and with the NT-CT treatment than with other treatments. These results show that adverse soil physical condition (increased BD and PR) development is limited to designated traffic zones when using no-tillage for irrigated crop production.