Abstract: The ever-increasing weight of agricultural machines exacerbates the risk of subsoil compaction, a condition believed to be persistent and difficult to alleviate by soil tillage and natural loosening processes. However, experimental data on the persistency of subsoil compaction effects on soil pore functioning are scarce. This study evaluated and quantified persistent effects of subsoil compaction on soil pore structure and gas transport processes using intact cores taken at 0.3, 0.5, 0.7 and 0.9 m depth from a loamy soil in a compaction experiment in southern Sweden (Brahmehem Farm). The treatments included four repeated wheelings with ∼10 Mg wheel loads. Water retention characteristics ( WRC ), air permeability ( k a ) and gas diffusivity ( D s / D o ) were measured. A dual-porosity model fitted the WRC well, and there was a reduction in the volume of macropores >30 μm in compacted compared with control soil for all soil depths. Averaged for all sampling depths and also for some individual depths, both k a and D s / D o were significantly reduced by compaction. Gas transport measurements showed that the experimental soil was poorly aerated, with local anoxic conditions at water regimes around field capacity in all plots and depths, but with significantly higher percentage anoxia in compacted soil. Our main findings were that: (1) commonly used agricultural machinery can compact the soil to 0.9 m depth, (2) the effect may persist for at least 14 years, and (3) important soil functions are affected.

Abstract: Soil compaction affects pore structure and thereby plant root growth. Elongation and anatomy of seedling roots of wheat (Triticum aestivum), barley (Hordeum vulgare), rye (Secale cereale), triticale (Triticosecale Wittmack) and maize (Zen mays) grown in uncompacted bulk field (U) and compacted headland (C) Orthic Luvisol developed from loess of the same field were compared. The seedlings were grown in a growth chamber for 7 days, in cores with undisturbed silt loam taken from 5 to 10 cm depths at compacted and uncompacted sites. Transverse root sections were taken from 25 to 30 mm behind the apex following imbedding in resin. Areas of cortex and vascular cylinder in the sections were determined using the Zeiss LSM Image Examiner. Total root length was smaller in C compared with U by, approximately, 50% for barley to 79% for triticale. Anatomical responses of the roots to soil compaction were related to the general shape of roots (circular or flattened), likely induced by the shape of pores. In the circular roots of wheat, rye and maize the primary anatomical response to soil compaction were the invaginations and associated cell deformation in the cortex. This was mostly pronounced in maize, with greater inherent root diameter. However, in the flattened roots of barley and triticale deformation of root cells was observed both in the cortex and vascular cylinder with less pronounced invaginations. Depending on plant species, the area of cortex and/or vascular cylinder decreased or increased in response to soil compaction. Total cross section area of roots increased in C compared to U among the small-grain cereals, from 9.5 in wheat to 132% in rye, while no differences could be detected in maize. The results indicate that the root elongation and anatomy exhibit considerable plasticity in response to soil compaction and strength of the local environment around the roots. (C) 2012 Published by Elsevier B.V.

Abstract: Context Nowadays, harvest operations are predominantly performed fully mechanized using heavy tractors or forestry machines. The resulting soil compaction may negatively affect the soil ecosystem.

Abstract: New non-tillage or reduced tillage agricultural practises are being increasingly adopted but generally result in higher soil compaction. Due to their recognised physical influence mainly through burrow creation, it is often claimed that earthworm activity could alleviate soil compaction in these systems. To put this assumption to the test, an experimental compaction event was carried out on one plot of arable land. The abundance and biomass of earthworms were evaluated in compacted (under wheel tracks) and non-compacted (between wheel tracks) zones, seven times over a two-year period. In addition, the functional consequences of earthworm activity, defined by burrow abundance assessed in 2D and 3D and water infiltration, were measured three times over the same period. The short-term (less than three months) effects of the compaction were clear: soil bulk density increased from 1.46 to 1.57 g cm −3 , the abundance and biomass of earthworms were greatly reduced (−40% and −70% respectively) and the number and continuity of macroporosity were lower under wheel tracks at least until a depth of 30 cm. After these initial detrimental effects, we observed a rapid recovery of earthworm populations with no statistical difference between compacted and control zones more than three months after the compaction. However, the recovery of soil functional properties linked to earthworm activity, macroporosity and water infiltration, was much slower and took between 12 and 24 months. Despite these modifications, there were no significant changes in soil bulk density with time during the two-year period. This study demonstrates that earthworms are important actors in the regeneration of compacted soil. Although the complete regeneration of compacted soil by earthworms is a slow process, agricultural practises that promote earthworm density and activity should be encouraged in reduced or minimum tillage systems.

Abstract: Adoption of no-till cropping systems continues to increase worldwide due to enhanced soil and water conservation, reduced inputs and maintained crop production. Soil compaction, particularly in grazed systems, can become a concern within no-till cropping systems and occasional tillage may be a method to relieve these concerns. However, there is no data within the US Southern Great Plains examining the impact of tilling long-term no-till wheat cropping systems and the potential subsequent impacts on runoff characteristics. The objective of this study was to evaluate the impact of tilling long term no-till wheat systems on runoff water quantity and quality. The study was conducted within a field that had been in no-till wheat with occasional grazing for seven years. Seven tillage treatments were evaluated, including: no-till, conventional till, and soil aeration using roller angles of 0°, 2.5°, 5°, 7.5°, and 10°. Rainfall simulation studies providing a 7 cm h−1 storm event were conducted approximately three months after tillage. Results showed that conversion from no-till to conventional tillage increased runoff volume by 38%. Total sediment losses were at least 2.8 times greater from conventional till plots than no-till and aerated treatments. Nutrient concentrations were similar among tillage treatments. However, total P and ammonium-N loads in runoff water were significantly higher from conventional till plots compared with other tillage treatments. Aeration did not provide a consistent trend and generally provided no significant improvement in runoff characteristics compared with no-till. Initial results indicate no advantage of tilling long term no-till wheat systems in regard to runoff quality and quantity three months after tilling.

Abstract: Soil compaction negatively influences many important soil functions, including crop growth. Compaction occurs when the applied stress, R, overcomes the soil strength. Soil strength in relation to com- paction is typically expressed by the soil precompression stress, Rpc. Deformation is assumed to be elastic and reversible as long as R e Rpc. This work examined soil stress-strain behavior as measured in situ during wheeling experiments and related it to the stress-strain behavior and Rpc measured on soil cores in uniaxial compression tests in the laboratory. The data analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on soils with a wide range of texture. Contradicting the concept of precompression stress, we observed residual strain, ?res ,a tR e Rpc. These observations were supported by stress-strain data measured in uniaxial compression tests, which likewise showed ?res 9 0a tR e Rpc. Residual strain was observed in the field whenR exceeded approximately 40 kPa, and when the ratio R/Rpc exceeded roughly 0.1, although ?res was very small at R/Rpc G 0.5. These values were similar to those obtained on confined uniaxial compression curves. On the basis of our findings, we question the use of Rpc as a measure of soil strength and call for a reevaluation of the precompression stress concept.

Abstract: Ecological restoration on roadsides confers several ecological benefits, but also poses significant challenges. Native plants used in restoration efforts must survive compacted soil, harsh microclimates, prolific invasive species, and pollution from road salts and vehicle emissions. Criteria for both site and species selection need to be developed to assist practitioners in restoring roadside environments. We transplanted seedlings of 9 grassland plant species into plots within 8 highway interchanges surrounding Ann Arbor, Michigan, United States. To see if they might predict plant performance in roadside restoration, we assessed 2 indices: the coefficient of conservatism (CC) as an index of affinity to undisturbed habitat; and the number of U.S. counties in which each species occurs as an index of distribution. We measured seedling survival, height, and biomass during the first growing season, and survival 1 year after transplant. We also measured soil characteristics, air temperature, and humidity at each interchange. We found that soil characteristics largely determined plant survival. Plants were more likely to survive in sandier soils than in soils rich in silt or clay that had high bulk density, high pH, and high conductivity. Although plant survival varied among species and interchanges, neither CC nor county-level distribution was a useful predictor of survival. Our results illustrate the importance of matching plant species with local soil characteristics when choosing restoration sites, and offer guidance to transportation officials considering roadside restoration with native plants, and practitioners working to restore any heavily disturbed site.

Abstract: Soil compaction is a form of physical degradation that causes soil densification and distortion that can lead to changes in three-dimensional soil structure variability. For this reason we proposed a method for mapping compaction in three-dimensional space (3D), based on simple soil-specific depth functions. This method, denoted the ‘top down’ method, is based on a multi-step approach that starts with a framework for selecting the best depth function, considers which shape best describes the soil-specific variation by depth and ends with an interpolation of the coefficients of the function across the field. Subsequently, for each interpolated point this function is solved in order to estimate compaction in 3D space. The top down method was evaluated using a cone resistance dataset, collected at the CULS (Czech University of Life Sciences) farm in Lany. The accuracy of this method in predicting cone-index variation in the 3D space was compared with the generally accepted 3D ordinary kriging interpolation, using descriptive statistics of the predicted values and cross validation. We found that the top down method better represented observed information and generally performs better than 3D kriging with a far smaller sample size. The cross validation results suggest that ordinary kriging can predict cone-index obtaining a value of root mean squared deviation (RMSD) of 0.54 at 10% soil profiles excluded, and 0.57 at 50% exclusion; on the contrary the top down mapping method obtains an RMSD value of just 0.47, at 10% exclusion, and 0.53, with 50% exclusion. We also found that the depth function method was more representative of the observed variability in the predicted dataset, avoiding the smoothing filtering effect typical of kriging interpolation. We then created a cone-index map of the CULS Lany field with a vertical resolution of 10 cm using the top down method. The map can be seen as a series of three videos where it is possible to observe the cone-index pattern in three-dimensions.

Abstract: This paper presents and compares the results from a series of in situ density-based and modulus-based compaction control tests that were conducted during construction of a coarse-grained soil embankment. To simulate current construction practices as closely as possible, these in situ tests were performed on an embankment that was constructed and compacted by a vibratory smooth drum roller in a series of lifts. During construction of the test embankment, the compaction process was monitored using the nuclear density gauge device and a number of alternative modulus-based devices, including the lightweight deflectometer, the dynamic cone penetrometer, and the soil stiffness gauge. Comparison of the in situ test results illustrates that point-to-point variability in measured values is quite common for each of these test devices, to varying degrees for the different devices that were examined. Consistent increases in measured soil properties from pass-to-pass of the compactor are considered critical for proper control of the compaction process, with some devices faring better than others in this area of performance. The measured modulus values correlated poorly to the nuclear density gauge dry unit weights, and also correlated poorly with other measured moduli when the results from different devices were compared. This lack of agreement was likely caused by a variety of factors including: variations in the magnitude of strain and rate of strain application between the different modulus-based devices, variations in the tested volume between the different devices, and variations in the local moisture content and matrix suction conditions. Finally, the effect of soil moisture content was shown to be critically important when interpreting the results from modulus-based tests, and the utility of multiple regression analyses was explored for including this effect.

Abstract: Livestock grazing of riparian areas can have a major impact on stream banks and stream integrity if improperly managed. The goals of this study were to determine the sediment and phosphorus (P) losses from stream bank soils under varying cattle stocking rates and to identify additional factors that impact stream bank erosion in the southern Iowa Drift Plain. The research was conducted on 13 cooperating beef cow-calf farms within the Rathbun Lake Watershed in south central Iowa. Over three years, stream bank erosion rates were estimated by using an erosion pin method. Eroded stream bank lengths and area, soil bulk density, and total P (TP) content in stream bank soil were measured to calculate soil and TP losses via stream bank erosion. The length of severely eroded stream banks and soil compaction of the riparian areas of the pastures were positively related to stocking rates. There was no direct relationship between bank erosion and stocking rate. These results suggest that use of riparian areas as pasture can negatively impact the integrity of the major source areas and that the impact could be reduced through management of livestock stocking densities within these riparian areas.

Abstract: The causes, adverse effects and control of soil compaction, with special reference to Southern African conditions, are reviewed. The main causes for soil compaction are the well-rounded and -sorted fine sand fraction of the aeolian sandy soils combined with compression by soil tillage equipment. Layers with high penetration resistance decrease rooting depth and density which lead to a reduction in plant nutrient uptake, water uptake and water-use efficiency. A system of deep tillage combined with controlled wheel traffic to predetermined lanes is recommended as a measure of control. S. Air. J. Plant Soil 1985, 2:109–114

Abstract: The impact of soil compaction on the yield of maize was studied at Malakandher Farm, Khyber Pakhtunkhwa Agricultural University Peshawar Pakistan which is located at in June 25, 2011. The maize variety Jalal was used in the trial. Total area was 1 hectare having 36 plots. Each plot was 30x5 m in size. 2

Abstract: The heavy traffic of agricultural equipment in citric orchards as a result of frequent application of pesticides and fungicides have led to soil compaction and a biological imbalance in these agricultural ecosystems, decreasing crop yields and increasing production costs The purpose of this work was to assess the effects of spontaneous vegetation (weed) management in interrows following the replacement of agrochemicals with alternative inputs known to have a low impact on the environment This experiment was conducted in a commercial orchard of ‘Murcott’ tangor ( Citrus reticulata , Blanco × Citrus sinensis , Osbeck) Highly soluble sources of NPK were substituted with a mixture of 65% rice bran + 35% castor bean meal (30% N), thermophosphate (175% P 2 O 5 ) and potassium sulfate (48% K 2 O) Synthetic pesticides were replaced with alternative pest controls, such as Bordeaux mixture and lime sulfur Mechanical mowing was used instead of herbicides, and the mowed weeds were spread under the citrus plants canopy for mulch This treatment, referred to as alternative management (AM), was performed for three years and compared with a control area, referred to as conventional management (CM), in which conventional cultivation practices and pesticide applications were maintained The soil compaction, the fruit yield and select biological parameters were used for our assessment When compared to the CM treatment, AM provided a higher vegetation cover and species diversity (especially for grasses), reduced soil resistance to penetration, better root growth in the topsoil layer, increased root colonization by arbuscular mycorrhizal fungi (AMF), increased viable spores in the soil and a higher leaf boron (B) concentration Furthermore, the infestation of the AM plots with the mealybug, Orthezia praelonga , was significantly lower, and the fruit yield was higher in the third year These results indicate that agricultural management practices focused on a reduced impact on the agroecosystem, mainly with regard to biological processes, are promising techniques for sustainable agriculture

Abstract: Crop livestock integration systems (CLIS) involving pastures of Brachiaria brizantha in autumn/winter and soybeans in summer have been considered an option to increase and diversify crop production and improve no-tillage system. This work aimed to evaluate the effect of grass desiccation timings or cattle grazing pressures on soil physical attributes and soybean yields in a crop-livestock integration system. The experiment was carried out on a dark red Latosol (Rhodic Eutrudox, US Soil Taxonomy) in southern Brazil. In the major plots, grazing pressures of 6.9, 9.4, and 16.5 animal unities per hectare were applied during 19 days to a pasture of Brachiaria brizantha cv. 'Xaraes', which phytomass was desiccated 30 days before soybean sowing (DBS). Ungrazed plots were desiccated 30, 44 and 52 DBS. Remaining phytomass of the pasture; soil bulk density, porosity and soil resistance to penetration; and yield of soybean cultivars 'BRS 294RR' and 'BRS 255RR' (sowed in subplots), were determined. Changes in soil physical attributes by animal trampling were concentrated on topsoil layer (0.0-0.05m), and soil compaction level was increased by the highest grazing pressure down the 0.2-0.3 layer. The yield of soybean cv. 'BRS 294RR' was increased with rising grazing pressures, whereas the yield of soybean cv. 'BRS 255RR' was not affected, showing that soybean genotypes had different responses to soil compaction level and, mainly, to remaining phytomass of pasture. In CLIS with high production of B. brizantha dry mass, soybean yields are closely associated to time interval between grass desiccation and soybean planting.

Abstract: Although a number of harvesting studies have assessed compaction, no study has considered the interacting relationships of harvest season, soil texture, and landscape position on soil bulk density and surface soil strength for harvests in the western Lake States. In 2005, we measured bulk density and surface soil strength in recent clearcuts of predominantly aspen stands (Populus grandidentata Michx. and Populus tremuloides Michx.) in the Chippewa National Forest in northern Minnesota. We stratified these clearcuts by the season harvested, soil texture, and topographic position. In nearly all cases, we observed higher bulk density and surface soil strength following harvesting compared with adjacent and similar but unharvested stands. Within harvested sites, fine-textured soils generally had higher surface soil strength (more compaction) than coarse-textured soils when harvested in the summer, and fine-textured sites harvested in the summer had higher surface soil strength than those harvested in the winter. Landscape position was an important factor only in fine-textured soils. Both summit and toeslope positions had higher surface soil strength following summer harvesting compared with winter harvesting. Overall, our results indicate that fine-textured soils located on both lower and upper slope positions and harvested during unfrozen soil conditions are most susceptible to compaction during logging.

Abstract: Plants require a relatively mechanically weak, open soil condition, conducive to easy and extensive root development, good aeration and water supply, when subsurface drainage is satisfactory. Conversely, much more compact conditions are desirable for good traction and the support of wheels and tracks. There are three primary ways of reducing the overall compaction of field soils by agricultural vehicles: (1) Reduction of the number of passes of conventional machinery, (2) Reduction of the vehicle mass and the contact pressure of wheel systems. (3) Confinement of the traffic to permanent or temporary wheel tracks (controlled traffic). The objectives of this study are: to define the optimum soil compaction, to explain the effects of excessive soil compaction on plant growth and soil physical conditions; to examine the methods of preventing and reducing of excessive soil compaction hazards; to present the the application of wide span tractor.

Abstract: Declines in forest productivity have been linked to losses of organic matter and soil porosity. To assess how removal of organic matter and soil compaction affect short-term ecosystem dynamics, pre-treatment and year 1, 5 and 10 post-treatment soil properties and post-treatment plant community responses were examined in a boreal trembling aspen (Populus tremuloidesMichx.)-dominated ecosystem in northeastern British Columbia. The experiment used a completely randomized design with three levels of organic matter removal (tree stems only; stems and slash; stems, slash and forest floor) and three levels of soil compaction (none, intermediate [2-cm impression], heavy [5-cm impression]). Removal of the forest floor initially stimulated aspen regeneration and significantly reduced height growth of aspen (198 cm compared to 472–480 cm) as well as white spruce (Picea glauca [Moench] Voss) height (82 cm compared to 154–156 cm). The compaction treatments had no effect on aspen regeneration density. At Year 10, heigh...

Abstract: Compaction is a method of in situ soil modification to improve its engineering properties. The paper aim is to present the light falling weight deflectometer applied in a laboratory and in situ to the compaction control for noncohesive soils. It also includes a short description of the method development history and ways of results interpretation. The study resulted in the correlations between test results obtained by means of the light falling weight deflectometer and degree of compaction for 4 groups of non-cohesive soil types.

Abstract: The soil resistance to penetration and shear can be used as indicators of soil compaction and to indicate the susceptibility of a soil to erosion. The objective of this study was to quantify and compare the impact provided by different land uses in a haplic cambissol in areas of permanent preservation, from the soil resistance to penetration and shear. The experimental area was located in an area of permanent preservation, the sub-basin of the Ribeira Iguape River - SP, with different land uses: banana cultivation - CBAN, degraded pasture - PDEG, silvopastoral system - MPIS and native forest - MNAT. The test for resistance to penetration was accomplished with a digital penetrometer compaction of manual effort, to a depth of 40 cm. The soil shear strength was determined by Vane Test at a depth between 0 and 5 cm. The degraded pasture was similar to native forest, with less resistance to penetration. The banana cultivation and silvopastoral system were the land uses with the highest resistance to penetration, bringing serious risk of erosion in areas of permanent preservation. The soil under native forest had lower shear strength. The cultivation of bananas, degraded pasture and silvopastoral system were the land uses with higher shear strength of soil, indicating that the use of these soils in areas of permanent preservation is promoting the same compression.

Abstract: Soil compaction under tractors tires is becoming a major concern as larger machines are being used in recent years. The heavy duty off-road machines particularly those related to agricultural practices drastically compact the soil causing higher energy consumption and lower yield. The size and form of the tire and soil interaction as well as soil type are important in stress distribution. The objective of this study was to develop a model for soft soil responding to tire pressure and axel load using finite element (FE) technique. A 2D-axisymmetric Drucker-Prager material FE model was developed for analysis of soil behaviour under different load and tire inflation pressure. A 2D symmetric Moony-Rivilin model was also used for soil and tire interaction and compared with measured field response data available in literature. The maximum soil-tire pressure of 83.7 kpa was found for 70 kpa inflation pressure and 15kN axel load which were approximately 30% less than the stress at the tire contact patch in the field test as reported in the literature. Maximum vertical stress at contact area was 98.6 kPa for 150kPa inflation pressure and 15 kN axel load which was not statistically significant while comparing with 101 kPa previously reported 3D analysis. The maximum distributed stress was found at tire side wall. Results also showed that 2D axisymmetric model is able to monitor the soil-tire stresses with an acceptable accuracy.

Abstract: The increase in forest-wildfire events around the world has revived the old debate regarding the practice of salvage logging and its effectiveness in comparison to the unlogged, natural regeneration of burned forests. Since the logging of burned trees may have undesirable outcomes in soil systems, such as soil compaction and nutrient losses, these changes could further cause disturbances to soil microbial-community activity. The aim of this study was to examine chemical and biological changes in soil under two post-fire practices: salvage logging and unlogged, natural regeneration of burned areas, in the recently burned Byria Forest in Israel. Results indicated that salvage logging had a short- lived effect on soil chemical and biological properties that was confined mostly to the first year after logging. Soil moisture was greatly affected by salvage logging, and drier conditions were found in the logged compared to the unlogged burned areas. Moreover, logging had a negative effect on microbial biomass, with reduced biomass in the logged compared to unlogged areas, which was more evident during the first year after fire. These findings support the recommendations in the literature to postpone post-fire practices such as logging or, in turn, to combine the two practices in order to create a mosaic of burned-logged and burned-naturally regenerated areas.