Increase In Soil Density Research Articles

Effects of soil bulk density on sessile oak Quercus petraea Liebl. seedlings

This article presents the results of laboratory examinations concerning the effects of soil bulk density on the growth of sessile oak Quercus petraea Liebl. seedlings. The soil for the study was collected from a nursery plot and then compacted into PCV pots in eight different bulk density levels ranging from 0.81 to 1.32 g cm−3. Oak seedlings were cultivated in controlled conditions for 76 days after sowing. The growth and mass parameters of particular seedlings together with the parameters of the assimilation apparatus and roots were measured, taking into account the share of various diameter roots in the root system. For the purpose of the experiment, 120 acorns were sowed, of which 73 seedlings were cultured. An analysis of the growth of the sessile oak seedlings revealed that a change in soil density significantly affected root system development, total height of seedlings and dry mass. It was observed that the dry mass of the root system as well as the area and length of the roots decreased with an increase in soil density. Root system reduction was noted, the size of which determines the proper development of the tree and ensures its stability. Besides a decrease in the root system, an increase in soil compaction also resulted in a reduction in the number of roots of a specified diameter. The first to be affected were the smallest roots, i.e., those with diameters up to 0.2 mm, which are responsible for the uptake of mineral components. It was confirmed that even a slight increase in soil compaction might negatively result in the growth of young seedlings, impeding root system development.

Investigation of soil density effect on suction induced due to root water uptake by Schefflera heptaphylla

AbstractAn increase in soil water suction due to root water uptake is significant for stability of slopes and landfill covers as it increases shear strength of soil by 50%. Coupled effects of soil density changes in soil hydraulic properties [i.e., soil water characteristic curve (SWCC) and hydraulic conductivity] and root characteristics (root depth, vertical root distribution) found in past experimental studies may affect soil water suction, which are not fully understood. The objective of this study is to numerically investigate these coupled effects of soil density by systematically comparing suction profiles under three different scenarios: (1) changes in only soil hydraulic properties, (2) changes in only root characteristics, and (3) changes in both soil properties and root characteristics. Silty sand with two different degrees of compaction (DoC) (i.e., 82% and 89%), which are typically found on man‐made slopes in subtropical regions, is considered. Schefflera heptaphylla is selected as vegetation species, which is commonly used for ecological restoration for man‐made slopes. A laboratory experiment was conducted to quantify suction distribution in silty sand vegetated with Schefflera heptaphylla at DoC of 89%. Vertical root distribution was measured using image analysis, while an axi‐symmetric finite element analysis was conducted to calibrate transpiration rate from measured suction. Root characteristics corresponding to DoC of 82% were then deduced using observations from literature. Richards equation coupled with sink term was numerically solved using Vadose/W to simulate water flow and root uptake on a flat ground (5 m depth, 10 m wide). Soil hydraulic parameters from a completely decomposed granite soil for two different DoCs (82% and 89%) were considered. Simulations assume constant transpiration rate for a period of 10 d. With increase in soil density from DoC of 82% to 89%, computed suction increases by 110% for scenario 1 (only effect on soil hydraulic properties), whereas it decreases by at least 21% for scenarios 2 (only root characteristics) and 3 (coupled effect). Here, a higher unsaturated hydraulic conductivity and a lower actual transpiration rate balance effects of a lower desorption rate of SWCC.

Influence of agro-ecological factors on winter wheat yield in the steppe zone of Ukraine

Results of long-term research of Zaporizhia State Agricultural Research Station (southern steppe zone) as to the impact of productive moisture reserves in the soil for sowing mild winter wheat on yields in the context of global climate changes are presented. The water regime deterioration in wheat sowing on black fallow during the vegetation period within phases of plant growth was discovered. It was noted that for the autumn-winter period (termination — resumption of vegetation) wheat sowing on black fallow absorbed only 27% of precipitation. The main reasons for the low level of precipitation absorption are the deterioration of agro physical characteristics of the soil, increase of soil density and reduction of its permeability.

Dirt road: A geomorphological and geochemical record of Late-Holocene human activity in the catchment of Lake Radacz (Central Pomerania, Poland)

The paper offers a discussion of the record of human activity in the relief and sediments of a selected lake catchment in Central Pomerania in Poland. One of the basic markers of human activity here is a change in the lake-water level. The dropping level (on average, 1 m/100 years) made it possible for people to develop successively exposed stretches of land along the shore. An analysis of the Polish National Archeological Records and archival maps showed that human development and impact appeared in the lakeshore zone as early as the Neolithic. In Central Pomerania, the changes were especially intensive in the Late Holocene; in the catchment of the lake under study they included a 100% increase in the length of nearby roads. In the archives of its paleoenvironmental data, most traces have been left on farming terraces, while a poorly studied form of record of human activity is a dirt road running parallel to the shoreline. Geodetic and geochemical examination has revealed that the road is a stimulant of change. Its wheeled traffic mixes the accumulated and eroded material, and this causes changes in the shoreline section: the road cutting, which is 2 m wide, deepened, while material accumulates in the form of 0.5-m-wide lateral bars. The compaction of the material brings about changes in the structure of the ground or soil (its density, porosity, compactness, moisture), which affects its level of oxygenation and waterlogging, and, consequently, its iron content. To establish this, a speciation analysis was carried out using the Fe(III)/Fe(II) ratio. It was determined that the lower the ratio, the higher the susceptibility of land to deformation owing to an increase in soil density, a drop in its water capacity, reduction conditions, and the predominance of Fe(II). The research discussed here is only a pilot study, but the authors see extensive opportunities for using speciation analysis in geoarcheology.

Behavior of geogrid–reinforced sand and effect of reinforcement anchorage in large-scale plane strain compression

This paper presents experimental investigations on the behavior of geogrid–reinforced sand featuring reinforcement anchorage which simulates the reinforcement connected to the wall facings in numerous in-situ situations. A series of large plane strain compression tests (the specimen 56 cm high × 56 cm wide × 45 cm long) was conducted. Standard Ottawa sand and 4 types of PET geogrids exhibiting 5% stiffness in the range of 750–1700 kN/m were used in this study. The specimens were tested by varying the relative density of sand, confining pressures, geogrid types, and reinforcement-anchorage conditions. Experimental results indicate that relative to unreinforced specimens, both anchored and non-anchored geogrid reinforcements can enhance the peak shear strength and suppress the volumetric dilation of reinforced soil. The studies on anchorage revealed that anchoring the reinforcement can restrain the lateral expansion of reinforced specimens, resulting in a substantial increase in shear strength and a reduction in volumetric dilation. The strength ratios of non-anchored specimens appeared to be insensitive to the reinforcement stiffness, whereas the strength ratios of the anchored specimens increased markedly with increases in soil density, reinforcement stiffness, and system deformation (i.e., axial stain). Geogrid anchorage contributed a large percentage of the total shear-strength improvement, nearly 3-times more than the contribution of the soil–geogrid interaction in non-anchored specimens. Lastly, an analytical model was developed based on the concept that additional confinement is induced by reinforcement anchorage, and the predicted shear strength of the anchored soil was verified based on the experimental data.

A modified creep index and its application to viscoplastic modelling of soft clays

Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index C αe with increasing soil density. Based on all selected and conducted experimental results, a modified creep index C* αe defined in double logarithmic plane lge-lgt, was plotted for various clays, from which C* αe can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index C* αe can naturally take into account the nonlinear C αe revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index C αe.

Shaking table tests to investigate the influence of various factors on the liquefaction resistance of sands

This paper presents the shaking table studies to investigate the factors that influence the liquefaction resistance of sand. A uniaxial shaking table with a perspex model container was used for the model tests, and saturated sand beds were prepared using wet pluviation method. The models were subjected to horizontal base shaking, and the variation of pore water pressure was measured. Three series of tests varying the acceleration and frequency of base shaking and density of the soil were carried out on sand beds simulating free field condition. Liquefaction was visualized in some model tests, which was also established through pore water pressure ratios. Effective stress was calculated at the point of pore water pressure measurement, and the number of cycles required to liquefy the sand bed were estimated and matched with visual observations. It was observed that there was a gradual variation in pore water pressure with change in base acceleration at a given frequency of shaking. The variation in pore water pressure is not significant for the range of frequency used in the tests. The frequency of base shaking at which the sand starts to liquefy when the sand bed is subjected to any specific base acceleration depends on the density of sand, and it was observed that the sand does not liquefy at any other frequency less than this. A substantial improvement in liquefaction resistance of the sand was observed with the increase in soil density, inferring that soil densification is a simple technique that can be applied to increase the liquefaction resistance.

Modeling and mapping soil resistance to penetration and rutting using LiDAR-derived digital elevation data

Soil resistances to penetration were probed with a hand-held soil cone penetrometer across ridge-to-depression transects for two contrasting study areas in Alberta, Canada: one in the foothills west of Calgary, and one in the boreal plain north of Peace River. The resulting cone index values (CI) were related to plot-measured values for soil moisture, density, texture, organic matter content, soil depth, elevation, slope, and a cartographic depth-to-water index (DTW) by way of multiple regression analysis. Elevation, slope, DTW, and the associated flow accumulation pattern were all derived from a light detection and ranging (LiDAR)-generated bare ground digital elevation model (DEM), at 1 m (3 ft) resolution. The field-determined CI values conformed to a previous formulation that related CI to soil texture, density, and water-filled pore space. In terms of topographic position, CI increased with increasing DTW, in parallel with decreasing soil moisture content and increasing soil density. The resulting best-fitted regression between CI, log₁₀(DTW), and elevation (or study area) was used to map CI and expected all-terrain recreational vehicle–specific rutting depths across the landscape. The maps so generated were in general agreement with the results of a 40 km (25 mi) long soil disturbance survey along a recreational vehicle trail section within the foothill area.

모래지반에서 표준관입시험에 따른 관입거동

본 논문에서는 표준관입시험(SPT) 중에 발생하는 관입거동을 표현하기 위한 이론식을 유도하여 나타내었다. 이를 위하여 에너지보존법칙을 도입하고 SPT 항타거동을 소형강관말뚝이 관입되는 것과 같이 모형화 하였다. 이론식에는 쉽게 결정하기 어려운 쌍곡선 매개변수(m과 <TEX>${\lambda}$</TEX>)를 포함하여 3종류의 입력정수 항으로 구성되어 있다. 최적화된 m과 <TEX>${\lambda}$</TEX>값은 3점에서의 측정값을 사용하여 시행착오법으로 구하였다. 체계적으로 측정된 기존의 자료로부터 얻어진 관입곡선과 예측 관입곡선을 비교한 결과 좋은 일치를 보여 주어서 본 이론식의 적용성이 입증되었다. 본 이론식에 의하면, 주어진 깊이에서 m값이 증가할수록 <TEX>${\lambda}$</TEX>값은 감소하고 관입곡선의 곡률과 N값은 증가하였다. 일반적으로 예측 관입곡선은 예비타 부분을 넘어서면서 거의 직선적으로 변하였으며, 이러한 경향은 모래가 조밀할수록 현저하였다. 그러므로 제안방법은 불충분하게 측정된 관입곡선으로부터 30cm 관입에 해당하는 N값을 외삽법으로 구할 수 있다. 이와 유사한 결과는 역시 간단한 직선식을 이용하여 구할 수 있다. This paper presents an equation to depict the penetration behavior during the standard penetration test (SPT) in sandy deposits. An energy balance approach is considered and the driving mechanism of the SPT sampler is conceptually modeled as that of a miniature open-ended steel pipe pile into sands. The equation consists of three sets of input parameters including hyperbolic parameters (m and <TEX>${\lambda}$</TEX>) which are difficult to determine. An iterative technique is thus applied to determine the optimized values of m and <TEX>${\lambda}$</TEX> using three measured values from a routine SPT data. It is verified from a well-documented record that the simulated penetration curves are in good agreement with the measured ones. At a given depth, the increase in m results in the decrease in <TEX>${\lambda}$</TEX> and the increase in the curvature of the penetration curve as well as the simulated N-value. Generally, the predicted penetration curve becomes nearly straight for the portion of exceeding the seating drive zone, which is more pronounced as soil density increases. Thus, the simulation method can be applied to extrapolating a prematurely completed test data, i.e., to determining the N value equivalent to a 30 cm penetration. A simple linear equation is considered for obtaining similar results.

Soil physical properties and grape yield influenced by cover crops and management systems

The use of cover crops in vineyards is a conservation practice with the purpose of reducing soil erosion and improving the soil physical quality. The objective of this study was to evaluate cover crop species and management systems on soil physical properties and grape yield. The experiment was carried out in Bento Gonçalves, RS, Southern Brazil, on a Haplic Cambisol, in a vineyard established in 1989, using White and Rose Niagara grape (Vitis labrusca L.) in a horizontal, overhead trellis system. The treatments were established in 2002, consisting of three cover crops: spontaneous species (SS), black oat (Avena strigosa Schreb) (BO), and a mixture of white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and annual rye-grass (Lolium multiflorum L.) (MC). Two management systems were applied: desiccation with herbicide (D) and mechanical mowing (M). Soil under a native forest (NF) area was collected as a reference. The experimental design consisted of completely randomized blocks, with three replications. The soil physical properties in the vine rows were not influenced by cover crops and were similar to the native forest, with good quality of the soil structure. In the inter-rows, however, there was a reduction in biopores, macroporosity, total porosity and an increase in soil density, related to the compaction of the surface soil layer. The M system increased soil aggregate stability compared to the D system. The treatments affected grapevine yield only in years with excess or irregular rainfall.

Soil physical properties of high mountain fields under bauxite mining

Mining contributes to the life quality of contemporary society, but can generate significant impacts, these being mitigated due to environmental controls adopted. This study aimed to characterize soil physical properties in high-altitude areas affected by bauxite mining, and to edaphic factors responses to restoration techniques used to recover mined areas in Poços de Caldas plateau, MG, Brazil. The experiment used 3 randomized block design involving within 2 treatments (before mining intervention and after environmental recovery), and 4 replicates (N=24). In each treatment, soil samples with deformed structures were determined: granulometry, water-dispersible clay content, flocculation index, particle density, stoniness level, water aggregate stability, and organic matter contend. Soil samples with preserved structures were used to determine soil density and the total volume of pores, macropores, and micropores. Homogenization of stoniness between soil layers as a result of soil mobilization was observed after the mined area recovery. Stoniness decreased in 0.10-0.20 m layer after recovery, but was similar in the 0-0.10 m layer in before and after samples. The recovery techniques restored organic matter levels to pre-mining levels. However, changes in soil, including an increase in soil flocculation degree and a decrease in water-dispersible clays, were still apparent post-recovery. Furthermore, mining operations caused structural changes to the superficial layer of soil, as demonstrated by an increase in soil density and a decrease in total porosity and macroporosity. Decreases in the water stability of aggregates were observed after mining operations.

Laboratory measurements of small strain properties of dry sands by bender element

The S-wave and P-wave velocities in dry sands are simultaneously measured by a single pair of bender elements (BE) incorporated into a standard resonant column (RC) apparatus with a torsional shear (TS) function. The small strain properties, including shear modulus G 0 , constrained modulus M 0 and Poisson's ratio υ , are determined for specimens at various densities and confining pressures. The results show that the G 0 values obtained from the BE tests agree well with those from RC and TS tests, indicating the reliability of the signal interpretation and the testing system. Furthermore, the G 0 data of the present test series is in good agreement with the data from the literature. The results also show that G 0 increases faster than M 0 as the soil density and the confining pressure increase. In terms of Poisson's ratio, it decreases with an increasing soil density and confining pressure and generally lies in the range of 0.18–0.32 for the tested sands. Empirical equations are established to approximately estimate Poisson's ratio from the measured G 0 or M 0 values.

Research on the Nonlinear Hysteretic Response Characteristics of Intelligent Vibratory Roller under Horizontal Excitation Mode

This paper introduced Bouc-Wen model to describe the elasticoplastic deformation of compacted soil on horizontal excitation, converts it to a direct polynomial expression using Taylor Expansion based on one order approximation. A 2-def dynamic model was established in terms of the simplified Bouc-Wen model. According to the first order approximation, the equivalent damping coefficient and equivalent stiffness coefficient were deduced through the harmonic linearization method. By means of numerical simulation, during the beginning of compaction ultra harmonics occur in drum, its spectrums present in addition to the fundamental wave only rich odd harmonics. With the increase of soil density during the compaction process, the slipping of the drum on the soil surface may be induced, the drum occurs from periodic motion to quasi periodic motion, its response spectrums and hysteretic loop would change along with the excitation amplitude-frequency changes. In theory the conclusion of the article is valuable to ensure the compaction quality and improve compaction efficiency.

Uplift capacity of single piles and pile groups embedded in cohesionless soil

Understanding the pile behavior and predicting the capacity of piles under uplift loading are important topics in foundation design. Experimental model tests have been conducted on single piles and pile groups embedded in cohesionless soil and subjected to pure uplift loading. The experimental tests were conducted on straight-shafted vertical steel piles with an outer diameter of 26mm in a steel soil bin. The tested piles have embedment depth-to-diameter ratios (L/d) of 14, 20, and 26. The sand bed is prepared at three different values of relative density of 75%, 85%, and 95%. Single piles and pile groups containing two, four, and six piles embedded in sandy soil were tested, and the results are presented and discussed in this paper. The influences of pile embedment depth, relative density of soil, and arrangement of piles in a group on the uplift capacity of piles are investigated. The study revealed that the behavior of single piles under uplift loading depends mainly on both the pile embedment depth-to-diameter ratio and the soil properties. An empirical equation is suggested to represent the load–displacement relationships of single piles embedded in sandy soil under uplift loading. When the net uplift load per pile in a group is equal to a single pile load, the upward displacement increased in the pile group due to interaction effects between piles. The obtained group efficiency under uplift loading is illustrated and found to be in a good agreement with previous studies. The uplift group efficiency of a closely spaced pile group decreased with an increase in the number of piles in the group. The group efficiency under uplift loading improved slightly with an increase in the relative density of soil, whereas it decreased with an increase in the pile embedment depth-to-diameter ratio. It is believed that the experimental results presented in this study would be beneficial to the professional understanding of the soil–pile-uplift interaction problem.

Impact of soil compaction on root development and yield of meadow-grass

Abstract The field experiment was carried out on a smoothstalked meadow-grass to analyse the effect of tractor traffic on herbage production and root morphology. The multiple passes of tractor changed physical properties of soil. Increase in bulk density and penetration resistance of soil under smooth-stalked meadow-grass was recorded up to the depth of 30 cm. The tractor traffic resulted in changes in smooth-stalked meadow-grass yields. During the second and the third harvest it was found that wheel traffic decreased plant yields. For the first harvest the opposite effect in herbage production was noticed. The tractor traffic significantly changed the root morphometric properties in the upper, 0-5 cm, soil layer. Intensive tractor traffic (four and six passes) significantly increased the root length in diameter range of 0.1-0.5 mm. There were no differences in both mean root diameter and specific root length what indicated that traffic treatment applied did not change the root diameter. The results indicate that smooth-stalked meadow-grass could be recommended for compacted soils when intensive traffic is present.

Soil Properties in Natural Forest Destruction and Conversion to Agricultural Land,in Gunung Leuser National Park, North Sumatera Province

Destruction of the Gunung Leuser National Park area of North Sumatera Province through land clearing and land cover change from natural forest to agricultural land. Less attention to land use and ecosystem carrying capacity of the soil can cause soil degradation and destruction of flora, fauna, and wildlife habitat destruction. Environmental damage will result in a national park wild life will come out of the conservation area and would damage the agricultural community. Soil sampling conducted in purposive sampling in natural forest and agricultural areas. Observation suggest that damage to the natural forest vegetation has caused the soil is not protected so that erosion has occurred. Destruction of natural forest into agricultural are as has caused damage to soil physical properties, soil chemical properties, and biological soil properties significantly. Forms of soil degradation caused by the destruction of natural forests, which is an increase in soil density (density Limbak) by 103%, a decrease of 93% organic C and soil nitrogen decreased by 81%. The main factors causing soil degradation is the reduction of organic matter and soil erosion due to loss of natural forest vegetation. Criteria for soil degradation in Governance Regulation Number 150/2000 can be used to determine the extent of soil degradation in natural forest ecosystems.

Soil compaction in forest soils

Soil compaction is a widespread degradation process in forest sites. Soil degradation occurring on the structural formation of a natural soil system by rainfall or mechanical outer forces generally results in soil particles to be rearranged tighter than its previous status. In this case, soil compaction -defined as the increase in bulk density of soil- develops with negative effects on soil-plant-water relations. With the compaction, the density of soil increases while the porosity rate decreases, creating a harder formation in soil and consequently lower degree of hydraulic conductivity. Higher soil compaction usually occurs in densely used places including recreational areas, settlements, logged forests, fruit gardens, agro-forestry systems and nurseries. The compaction may occur naturally, but it can also be started by outer factors such as soil preparation tools, heavy equipments, tire traffic, livestock grazing or fires. Besides causing deterioration on physical and hydrological features in growing environments of plants, soil compaction may also lead to physiological degradation of plants and changes on the balance and amount of growth hormones of plants, which, in turn, may limit nutrient uptake. In this study, possible reasons for compaction problem observed in forested soils and its negative effects on soil physical, chemical and microbiological characteristics as well as on the physiology of plants were evaluated.

The relationship between plant species richness and soil aggregate stability can depend on disturbance

AimsPlant diversity has been shown to significantly increase topsoil aggregate stability of machine-graded ski slopes. We hypothesise that this effect is specific for these disturbed sites and that at sites of low and no disturbance the effect decreases.MethodsWe determined plant species richness, cover percentage of five functional groups, root (length) density, and biomass as well as soil aggregate stability, gravimetric soil moisture, soil density, and particle size distribution at different levels of disturbance (i.e. graded and un-graded ski slopes and the surrounding area).ResultsPlant species richness, vegetation cover, aggregate stability and soil moisture were significantly reduced on machine-graded slopes compared to control plots but hardly on un-graded slopes. On the contrary, machine-grading increased soil density and friction angle compared to un-graded ski slopes. The influence of species richness on aggregate stability was only positive on gravely soils and graded ski slopes. Aggregate stability increased linearly up to approximately eight plant species, 70% vegetation cover and 0.006 g cm−3 root density.ConclusionsOur study showed that the relationship between plant diversity and aggregate stability was strongest on slopes with high disturbance and relatively low species numbers. We suggest that high plant diversity, vegetation cover and root density need to be established after major human disturbance such as grading.

Application of Magnetic Resonance Techniques to evaluate soil compaction after grazing

Abstract Grazing constitutes one of the most important processes of soil degradation due to compaction, and it affects both vegetation and soil in arid and semiarid ecosystems. Compaction modifies the soil structure and causes an increase in the proportion of small aggregates, which consequently leads to an increase in bulk soil density. Com-paction also produces a decrease in soil organic carbon content. The soil becomes more densely packed, causing reductions in porosity and storage capacity.Magnetic Resonance Imaging (MRI) was used to obtain a relative estimate of soil water content and porosity. The signal intensity from proton density images, which corresponds to the amount of water present in a sample, is lower in compacted soil. As calculated from the image signal intensity, the porosity percentage is also lower in grazing soils in comparison with natural recovery soils.H NMR relaxometry studies demonstrate shorter T2 and T1 relaxation times in graz-ing soil samples, suggesting lower pore sizes in these soils. Moreover, the grazing samples have a monomodal distribution of T1 with a narrow band, indicating greater homogeneity in the pore sizes. The bimodal distribution of T2 complements this result and indicates a greater proportion of smaller-size pores with greater homoge-neity between them.There is a significant positive correlation between the porosity values determined by both methods, which demonstrates the validity of the MR technique. The relaxation times also show positive and significant correlations with analytical porosity.The application of MR techniques to soil compaction studies demonstrated the natu-ral recovery of the physical properties of deteriorated soil after grazing damage in pastoral systems brought about by complete animal exclusion for ten years.

Persistência do efeito de intervenções mecânicas para a descompactação de solos sob plantio direto

A compactação tornou-se uma das principais causas de degradação do solo em áreas agrícolas, estando diretamente relacionada ao sistema de manejo do solo adotado e, muitas vezes, demandando práticas de descompactação para mitigar esse problema. Este trabalho objetivou avaliar a duração do efeito de intervenções mecânicas, como a aração e escarificação do solo associadas à ação de semeadora de plantio direto equipada com mecanismos rompedores de solo tipo discos e discos + facão, como práticas mitigadoras da compactação de um solo manejado sob o Sistema Plantio Direto (SPD), por meio da avaliação de atributos físicos do solo e do esforço de tração. O estudo foi realizado no município de Coxilha, na região Norte do Rio Grande do Sul, localizado nas coordenadas geográficas de 28°10'18,7" S e 52°22'39,89" O, sobre um Latossolo Vermelho, em experimento instalado no ano de 2001 em área com histórico de oito anos sob SPD. Nessa área foram realizadas intervenções mecânicas anuais, mediante a aração e escarificação do solo, anteriores à implantação da cultura de verão. Os tratamentos de manejo do solo constituíram- se da testemunha, com manutenção ininterrupta do SPD por 16 anos e por seis períodos de tempo de condução desse sistema (7,5; 6,5; 5,5; 4,5; 3,5; e 2,5 anos) após a escarificação ou aração, aplicados nas parcelas principais. Nas subparcelas foram aplicados dois tratamentos de dispositivo de aplicação do adubo no sulco de semeadura (discos duplos defasados e facão + discos). O delineamento experimental adotado foi de blocos completos casualizados com parcelas subdivididas e três repetições. Os resultados indicaram a existência de compactação na camada subsuperficial do solo, situada entre 7 e 15 cm, evidenciada por aumentos na densidade e redução na porosidade total e macroporosidade do solo em todos os tratamentos avaliados. Observou-se que a intervenção mecânica apresenta potencial efêmero para mitigar a compactação e melhorar a estrutura do solo, com duração de até dois anos e meio dos atributos porosidade total e macroporosidade após a escarificação, e a densidade do solo depois da aração. Nos demais atributos avaliados, tais benefícios deixaram de ser perceptíveis em período inferior a dois anos e meio após a intervenção mecânica, o que não provocou alterações na força exercida na barra de tração do trator agrícola, comparativamente à testemunha. Contudo, o mecanismo facão + discos de rompimento do solo na semeadora foi efetivo em alterar os atributos avaliados, aumentando a macroporosidade, diminuindo a microporosidade, a densidade do solo e o esforço de tração e auxiliando, assim, na mitigação da compactação do solo.