Abstract: The main function of deep tillage is to alleviate subsoil compaction, but how long do the benefits of this technique remain? Traffic on loose soil causes a significant increase in soil compaction. Subsoiling and chisel plowing were carried out at 450 and 280 mm depth, respectively on a compacted soil in the west Rolling Pampas region of Argentina. The draft required, physical soil properties, root growth, sunflower ( Helianthus annus L. Merr.) yield and traffic compaction over the subsequent two growing seasons were measured. Cone penetrometer resistance was reduced and sunflower yields increased following deep tillage operations. Subsoil compaction caused changes to the root system of sunflower that affected shoot growth and crop yields. Although subsoiling and chiseling had an immediate loosening effect, it was evident that after just 2 years, when traffic intensity was >95 mg km ha −1 , re-compaction and settling had occurred in the 300–600 mm depth range.

Abstract: We tested three disturbance hypotheses in young conifer plantations: H1: soil compaction and removal of surface organic matter produces sustained changes in microbial community size, activity, and ...

Abstract: The cultivation of cover crops with vigorous root systems in crop rotation can improve the physical quality of compacted soils. The objective of this study was to evaluate shoot and root growth of soybean (Glycine max) and five species used as summer cover crops (Cajanus cajan, Cajanus cajan var. small, Mucuna aterrima, Dolichos lab lab and Crotalaria juncea) in a soil submitted to three different levels of subsurface compaction. Plants were grown in pots assembled with three PVC rings, 50 cm high and with 20 cm internal diameter, filled with a clay-textured Red Nitosol. The soil layer at 20-30 cm depth was compacted to a bulk density of 1.13, 1.34 and 1.56 g cm-3 with 0.26, 0.66 and 1.98 MPa mechanical impedances, respectively. Sixty days after plant emergence, plants were harvested and it was determined the shoot and root dry matter, root length density, and root mean diameter. In spite of altering the root system distribution along the soil profile, the subsoil physical impediment did not reduce the total root dry matter of soybean and cover crops, except for Crotalaria juncea. Mucuna aterrima was the most tolerant and soybean the most sensitive of the leguminous species to soil compaction. Crotalaria juncea roots showed a potential of forming "biopores" comparable to those of Mucuna aterrima, in spite of being relatively more sensitive to soil compaction. Mean root diameter of soybean and Crotalaria juncea showed significant correlation to root growth in the compacted soil layer.

Abstract: A statistical study of the effects of compaction delays on properties of lime-stabilized lateritic soil was conducted using two-way analysis of variance and multiple regression analysis. The reductions in mavimum dry density (MDD) and optimum moisture content (OMC) associated with compaction delays are statistically significant at the 5% level, regardless of the compactive effort employed (i.e., standard Proctor or West African Standard). The effects of compaction delays on unconfined compressive stength (UCS) are statistically significant for different compactions, lime contents, and curing. Compaction delay effects on California bearing ratio (CBR) of soil–lime mixtures are statistically significant. The t -statistics from regression analysis show that compaction delays significantly influence the measured values of MDD, OMC, UCS, and CBR. It is believed that the findings of this study will be helpful in controlling the compaction delay for lime-treated soils.

Abstract: We tested three disturbance hypotheses in young conifer plantations: H1: soil compaction and removal of surface organic matter produces sustained changes in microbial community size, activity, and structure in mineral soil; H2: microbial community characteristics in mineral soil are linked to the recovery of plant diversity; and H3: community responses are strongly modified by regional climate. Microbial biomass, respiration, carbon utilization, and phospholipid fatty acids were compared at two subtropical installations and one Mediterranean-type climate installation of the North American Long-Term Soil Productivity study. Treatments included combinations of compaction (none vs. severe), organic matter removal (none vs. complete), and weed control (none vs. complete), plus an uncut reference stand. Weed control resulted in the only consistent decline or shift in microbial indices at the subtropical sites. At the Mediterranean-type climate site, overstory harvesting resulted in declines in microbial biomass, respiration, and fungal phospholipid fatty acids that far outweighed the effects of the soil disturbance treatments. Severe compaction had no effect on community size or activity at any site. Microbial communities were generally tolerant of postharvest soil disturbance, leading to a rejection of the experimental hypotheses, with the exception of a link between microorganisms and recovery of plant

Abstract: Field trials were conducted for a period of 5 years at two locations in north Queensland and with four sugarcane varieties to quantify the effect of harvest traffic on soil physical properties and sugarcane growth. The trials were conducted under rain-fed conditions. Treatments consisted of wheel traffic directly over the planted row, 0.1 m from the row and down the middle of the inter-row, by fully laden haulout equipment immediately after harvest. The equipment varied between sites, with low ground pressure tyres being used at one-site and high ground pressure tyres being used at the other site. This reflected commonly used harvesting equipment for each area. Gravimetric soil water content was 23–29 and 26.5–33% at the time of treatment application, which corresponds, to 0.7–0.9 and 0.8–1.0 of the plastic limit for the respective soils. Undisturbed cores were extracted for determination of bulk density and saturated hydraulic conductivity. Soil cone resistance was measured in the field. All measurements were made before and after impact on the plant crop and after impact on each ratoon crop. Stalk numbers, heights of stalks and number of gaps in cane rows were recorded to assess treatment effects, and final yield was measured. Experimental design was split-plot, with the main plot being position of wheel impact and the plot being split by varieties. Saturated hydraulic conductivity decreased and bulk density increased and soil cone resistance was variable in the row after traffic over the row compared with the near- and inter-row positions. Stalk numbers and heights and yield indicated little difference with respect to treatment, but there was a significant varietal difference. The varieties Q138 and Q124 were taller and had greater yield than Q117 and Q115. The effect of traffic appeared to be cumulative, as the degree of soil compactness and bulk density increased, with treatment differences becoming significant with each additional year of traffic. Traffic over the row resulted in a yield loss compared with traffic near-the-row and down the inter-row. To predict crop response to machinery traffic in the Australian sugar industry the model of Arvidsson and Hakansson [Arvidsson J., Hakansson, I., 1991. A model for estimating crop yield losses caused by soil compaction. Soil Tallage Res. 20, 319–332] was modified. Several changes were necessary, since the original model was developed for a cropping system based on annual cultivation, whereas sugarcane is a perennial crop grown in rows with no annual cultivation. The modified model was validated using data from the trials described in this paper. Agreement between measured yield loss and predicted yield loss was reasonable. This is the first attempt to provide the Australian sugar industry with a tool to assess the yield loss due to harvesting traffic and the economic cost of that loss. The model has the potential to provide, with further development, an indication to growers as to the benefit of restricting traffic to the inter-row area, restricting the number of passes by haulouts, harvesting under drier soil conditions and using high flotation haulout equipment. This should aid in more informed management decisions with respect to harvesting equipment or to the consequences of harvesting under adverse soil conditions.

Abstract: This study describes the main treatment effects of organic matter removal and compaction and a split-plot effect of competition control on mineral soil carbon (C) and nitrogen (N) pools. Treatment effects on soil C and N pools are discussed for 19 sites across five locations (British Columbia, Northern Rocky Mountains, Pacific Southwest, and Atlantic and Gulf coasts) that are part of the Long-Term Soil Productivity (LTSP) network and were established over 5 years ago. The sites cover a broad range of soil types, climatic conditions, and tree species. Most sites showed increased soil C and N levels 5 years after study establishment; however, the rate and magnitude of the changes varied between sites. Organic matter removal, compaction, or competition control did not significantly affect soil C and N contents at any site, except for the Northern Rocky Mountain site, where competition control significantly affected soil C and N contents. The observation that, after 5 years, the soil C and N contents were not negatively affected by even the extreme treatments demonstrates the high resiliency of the soil, at least in the short term, to forest management perturbations.

Abstract: Soil compaction effects on maize (Zea mays L.) plant population, height, and yield were studied from 2002-2005 in a no-tillage/in-row tillage study on a Hublersburg silt loam soil (Typic Hapludult) in Pennsylvania. Soil was compacted annually with a three-axle truck with 10-Mg axle load mounted with road tires (700 kPa inflation pressure) or flotation tires (250 kPa). In another treatment, soil was only compacted with road tires in the first year without subsequent compaction. Re-mediation treatments were deep (40 cm) in-row tillage before or after compaction with road tires and shallow (10 cm in 2002-2003 and 22 cm in 2004-2005) in-row tillage after compaction. Significant yield reductions averaging 17% in 3 yr out of 4 were observed for annual compaction with road tires compared with control (no-tillage without compaction). Compaction with flotation tires reduced yield significantly in 1 yr only. Yield reductions due to compaction disappeared after 1 yr. Deep tillage after compaction increased yield (17%) in 1 yr only, whereas shallow tillage did not increase yields. Yield improvements due to deep tillage were lost if it was followed by heavy traffic. Deep tillage and no-tillage without compaction gave similar yields in the first 3 yr, but no-tillage had higher yield in 2005. In-row tillage substantially reduced residue cover. Our results suggest little need for in-row tillage to manage compaction in long-term no-tillage when axle loads are no more than 10 Mg and flotation tires are used to keep inflation pressures below 250 kPa.

Abstract: Fundamentals of Plant Stress Physiology. Heat Stress. Cold Stress. Drought. Salinity. Flooding. Light. Nutrients. Soil Acidity. Soil Pollutant. Soil Compaction. Oxidative Stress. Pathogens. Methodology of Stress Tolerance Evaluation. Linking Stress Physiology/Molecular Biology to Biotechnology and Breeding.

Abstract: Intercropping pearl millet with cowpea is a common practice in semiarid areas. Under limited water environments, competition for soil water between intercropped plants may be strong. Furthermore, the increasing soil compaction problems, due to the use of heavy machinery, may intensify competition for limited resources, particularly in the topsoil. Two field trials were conducted to evaluate the water competition ability of intercropped pearl millet when subjected to drought and soil compaction during the 2004 Japanese summer. For this purpose plant water sources were determined by the hydrogen stable isotope (deuterium) technique. Plant water relations and biomass production were also evaluated. According to the deuterium concentration values in xylem sap, pearl millet water sources were changed by the competition with cowpea. Pearl millet was forced to rely more on recently supplied (irrigation/rainfall) water. In contrast, the water sources of cowpea were unchanged by plant competition. When plants were subjected to drought, the transpiration rate of pearl millet was reduced by 40 % of its monocropped potential by competition, but that of cowpea was not. Moreover, intercropped pearl millet, under drought and soil compaction, showed lower leaf water potential and biomass than their respective monocropped counterparts. Cowpea had a higher competitive ratio under wet, dry, and compaction treatments, while pearl millet was more competitive under loose conditions. In conclusion, under drought and soil compaction, water competition restricted the water use of intercropped pearl millet, forcing pearl millet to shift to the recently supplied water. In contrast, cowpea did not show any significant changes under these stress conditions.

Abstract: In 1996, a multidisciplinary group of researchers at the University of Kentucky initiated a study on the Starfire surface mine in eastern Kentucky to evaluate the effects of soil compaction and two organic amendments on the survivability and growth of high value tree species. Three types of prepared rooting medium were examined: compacted spoil, lightly compacted spoil, and uncompacted spoil. The compacted spoil was prepared using normally accepted spoil handling techniques that resulted in a smooth graded surface. The lightly compacted spoil was loose-dumped and struck-off with one or two passes of a bulldozer. The uncompacted spoil was loose-dumped and not further disturbed. In addition, organic amendments (mulches) were evaluated within the three reclamation techniques. The organic amendments used were processed hardwood bark mulch and a combination of straw and horse manure mulch. The following six species of trees were planted: white oak (Quercus alba), white ash (Fraxinus americana), eastern white pine (Pinus strobus), northern red oak (Quercus rubra), black walnut (Juglans nigra), and yellow poplar (Liriodendron tulipifera). Five of the six species, the exception being white ash, showed increased survivability as compaction was minimized. Additionally, the loose-graded techniques led to enhanced growth in height for the seedlings. The addition of organic amendments also showed additional benefit but results varied by species and by treatment. Results definitively show that strike-off and loose-dump techniques improve seedling height and survival. The data also suggest that even a small amount of traffic (i.e., one or two passes per the strike-off method) may result in enough compaction to significantly reduce survival and growth in some species, such as yellow poplar and white pine. In the backfilling and grading process, spoil material should be placed and compacted according to standard engineering practices so that the required stability and approximate original contour is achieved. However, the top 1.2 to 1.8 meters (4 to 6 feet) of material should not be graded or only lightly graded so that it is as uncompacted as possible.

Abstract: Soil water content and management systems can promote changes in compressibility parameters. The objective of this research was to study the effects that water content and sugarcane management systems have on the compaction degree and compressibility parameters of a cohesive Yellow Argisol. Four sites were selected in the surroundings of the sugar mill Triunfo, in the state of Alagoas, Brazil; one site with irrigation and a second without irrigation, a third with vinasse application and a fourth under native forest, taken as representative of the original soil condition. Samples from each site were collected at 0-0.2, 0.2-0.4 and 0.4-0.8 m depths and at 0-0.2 and 0.2-0.4 m, to determine alterations in the soil compaction and compressibility parameters, respectively. Management systems with and without irrigation increased the degree of soil compaction and resistance of aggregates to rupture as compared to those of the soil under native forest, resulting in an increase in the soil load support capacity. The increases in the soil water content reduced precompaction pressure and enhanced the compression index, resulting in a lower soil load support capacity.

Abstract: Soil degradation processes may be of various kinds, including soil compaction. The present study was carried out with the objective of assessing the sensitivity of agricultural or recently abandoned soils in Maputo province of Mozambique to compaction. The assessment is based on the maximum of bulk density attained using the Proctor test (MBD). In this study the soil texture is expressed by silt plus clay (S + C) or clay (C). The relations between the soil texture and MBD, and between soil texture and critical water content (CWC—soil water at which MBD is attained) were determined. Selected soils range from 10 to 74% of S + C and 9 to 60% of C. The results suggest there is a relationship between the considered parameters, being that between S + C and MBD or CWC, the best. For MBD the relationship is represented by two quadratic equations with the boundary in between these being a S + C value of 25% and C value of 20%. Based on the obtained results, one can conclude that the selected parameters may be a useful basis for estimation of the sensitivity to compaction of the Maputo province's soils. It is recommended that similar studies be carried out for soils under forest land and for soil of other provinces to establish the national physical degradation hazard as a function of soil parameters determined routinely and at low cost. The suggested parameters are texture and soil organic matter (SOM).

Abstract: The effects of the passage of forwarders on soil and damage to spruce root systems along an experimental trail were studied. The site was characterized by medium-textured soil of the pseudogley type under favorable moisture conditions. Due to the passages, the soil was compacted down to a depth of 20 cm, soil porosity was decreased by 5% (volume) and soil aeration was decreased by more than 5%. Substantially higher values of mechanical soil resistance occurred (estimated by penetrometric measurements) in a soil pit situated in a rut after passages. Pressure measured by sensors placed at a depth of 10 cm below the soil surface reached values ranging from 0.09 to 0.11 MPa in plots uncovered with slash and 0.03–0.07 MPa in plots covered with slash after two to four passages, and 0.06–0.07 after six to ten passages. Soil surface deformations occurred in the upper soil layers through tire impression. This resulted in the origin of ruts, whose depth and width was dependent on the type of tires, their load, surface conditions, type and texture of soil, soil moisture and number of passages. Pressure in the soil layers imposed by the tire of a given type, inflation and load changed in relation to depth, ground cover, soil properties and reinforcing components on the soil surface. Sap flow in coarse roots actually treated by a moving heavy load clearly and immediately responded with a sharp increase followed by a similar decrease (peak flow) after several minutes. On average, the flow rate decreased by about 8% after the first treatment compared to the untreated state, and remained the same after passing the peak during the second pass when the maximum load was applied. However, this decrease amounted to about 40%, when compared to the “relative zero flow” after root severing. This indicates serious local damage to the conducting system. Even when loading directly damaged rather small fractions of the total root systems, it opened tree tissues to subsequent fungal infection, whose impact could be very serious in future years. Flow in stem sections oriented in the opposite direction to the trail and the flow in stem sections and root buttresses oriented toward the trail (but where roots were not actually growing below the trail or grew deeper in the soil), neither responded to the treatment or responded insignificantly. Sap flow responded only in surface roots below trails, occurring down to a depth of about 10 cm below the original soil (litter) surface. This occurred only when a significant part of the roots (with the total projected area of treated root branches more then 500 cm2) were under the tires. This indicates the protective ability of soils and also, a possible method of artificial root protection.

Abstract: Soil compaction generally reduces crop performance because of degraded soil physical and biological properties, and possibly inappropriate soil nutritional status. The effects of varying compaction, and phosphorus (P) and zinc (Zn) supplies on the growth of Berseem or Egyptian clover ( Trifolium alexandrimum ), and accumulation of P and Zn in shoots and roots were investigated in a pot experiment using a surface layer of a Typic Torrifluvent (USDA), Calcaric Fluvisols (FAO) soil. Plants were treated with three soil compaction levels, three rates of P and three rates of Zn in a factorial combination. Phosphorus accumulation in shoots did not change up to bulk densities of 1.65 Mg m −3 and declined at bulk density of 1.80 Mg m −3 . Increasing the levels of Zn and P resulted in a significant increase in shoot dry mass (from 0.3 to 0.8 g pot −1 ), and root length (from 11.4 to 32.5 m pot −1 ). Shoot and root growth were reduced by soil compaction particularly at low P and Zn application rates. Shoot dry mass was reduced from 0.8 to 0.3 g pot −1 , and root length from 43 to 5 m pot −1 at bulk densities of 1.4 and 1.8 Mg m −3 , respectively. However, the accumulation of P (from 0.06 to 0.15 g kg −1 ) and Zn per unit length of roots (from 0.8 to 1.8 μg pot −1 ) increased as soil compaction increased. As the Zn supply increased, Zn accumulation per unit length of roots, and total Zn accumulation increased. Severe compaction reduced P and Zn accumulation in shoots and also decreased shoot dry mass, and root length compared to lower soil compaction levels. The present study suggests that Zn and P supply can moderate the adverse effect of soil compaction on clover performance.

Abstract: This report describes an intelligent compaction demonstration project on Minnesota Department of Transportation (Mn/DOT) TH 53 in Duluth, Minnesota, and the associated field and laboratory testing. The project was conducted during September 2005, using a Caterpillar Model CS-563E vibratory soil compactor, equipped with Intelligent Compaction [both Compaction Meter Value (CMV) and energy or power] and global positioning system (GPS) technology. A Prima light-weight deflectometer (LWD), dynamic cone penetrometer (DCP) and Humboldt GeoGauge were used to collect in situ companion test data at 42 locations. Mn/DOT conducted gradation, moisture content and Procter tests. Location and CMV were downloaded for comparison with the in situ testing. CMV data were compared to the in situ data on a point-by-point basis and on the basis of the overall distribution. In general, poor correlations were obtained on a point-by-point basis, likely due to the depth and stress dependency of soil modulus, and the heterogeneity of the soils. Good correlations were obtained between CMV values and DCP measurements for depths between 8-in. and 16-in. deep. The Caterpillar Compaction Viewer software, although still in development at the time of testing, is functional and is well integrated with GPS. It is easy to extract data and do more sophisticated analyses. Surface-covering documentation adds value by identifying potential problem areas where compaction is limited by material, moisture or subgrade deficiencies. LWD testing protocol must be followed to obtain useful results, since measurements vary significantly between successive tests. Relatively good correlations were obtained between LWD and GeoGauge. The GPS technology used for the demonstration is not adequate to distinguish between lifts.

Abstract: Steppe desertification due to vehicle travel is a severe environmental issue in Mongolia. We studied natural vegetation recovery on abandoned vehicle tracks in the central Mongolia steppe through vegetation surveys and stable isotopic techniques. The following issues were addressed: (i) invasion of pioneering plant species, (ii) alteration of soil surface features, and (iii) contribution of revegetated plants to soil organic matter (SOM). The pioneering plant species that firstly invaded the abandoned tracks are those that could germinate, root and survive in the compacted track surface.Salsola collina is one of these candidate plants. Due to revegetation, soil surface hardness was reduced. With the improvement of surface microenvironmental conditions, other plants began to colonize and establish; concomitantly species richness and species diversity increased. Carbon isotope ratios of SOM at the top surface layer indicated that C4-derived carbon contributed more to SOM in the early phase of recovery and decreased with further recovery

Abstract: The Intelligent Compaction Control (ICC) consists of continuous compaction control/monitoring compaction using rollers with adjustable compaction energy ( amplitude, frequency, and roller speed ). In ICC, a number of parameters are measured: displacements/amplitude of the roller (up and down) using the drum mounted accelerometer, frequency, roller speed, and various relative bearing capacity or equivalent stiffness/density values. This paper gives an introduction to ICC and application of ICC for highway embankment projects in Kansas. Three test sections on two routes were compacted using a Bomag Variocontrol (BVC) intelligent roller that produces real time stiffness values of compacted soil. Traditional compaction control measurements included density testing using a nuclear gage, moisture measurements using a speedy moisture tester, and soil bearing capacity measurements using a Dynamic Cone Penetrometer (DCP). The results showed that the intelligent compaction (IC) roller continuously measured the stiffness of soil under compaction and thus, was able to identify locations with lower stiffness in the spatial direction. In general, density increased with multiple passes of the IC roller. The IC roller stiffness was fairly sensitive to the moisture content and the percent compaction obtained in the field. Poor correlation was observed between the BVC stiffness and the CBR values calculated from the DCP results.

Abstract: The present invention includes a device and method for more particularly evaluating the compaction of soil by automating the use of a prior art dynamic cone penetrometer such that user error and error caused by field conditions are eliminated. Recordation of penetrometer data previously not recorded is made more precise by the present invention such that standardized measurement results. The device further includes means for facilitating the determination of compaction of soils through keyhole openings and a means for automating the collection and processing of the generated compaction data.

Abstract: The Pantanal is one of the faunistic provinces considered as a priority area for invertebrate conservation. However, it is one of the areas in Brazil where the local fauna is less assessed, thus needing more scientific information that could allow political decisions to be made regarding conservation. The continuous pressure for new pasture areas leads to improper habitat occupation and destruction, like fragmentation of forest areas in the region. Such alterations can cause different impacts on the local fauna, including the soil arthropods. The main objective of this work was to compare the morphospecies composition, diversity and density of the soil arthropod fauna between a secondary single species forest (Cambarazal) and a cultivated pasture with exotic and native grass species, using only pitfall traps as sampling method. We found a great variation on the vegetal cover among environments. A higher humidity in the forest soil was observed, as well as a greater compaction of the soil in the cultivated pasture. A total of 3635 individuals were collected, belonging to 214 different morphospecies. 139 morphospecies were collected in the forest (37% exclusive to this environment), while 134 morphospecies were collected in the cultivated pasture (35% exclusive). The diversity was higher in the forest (H′ = 1.634) than in the cultivated pasture (H′ = 1.253). However, considering the area as a whole (forest and pasture) the global diversity was increased. In this paper we discuss about the effects of environmental changes on soil arthropod diversity and propose a hypothetical model for invertebrate management in mosaic ecosystems.

Abstract: . Four experiments studying ground preparation for the restoration of disturbed land to a woodland cover are described. They provide consistent evidence to suggest that methods of soil replacement which minimize compaction are preferable to conventional methods followed by deep ripping to relieve compaction induced in the placement operation. In addition, soil loosening using an excavator is more effective than that achieved by ripping. The research supports modern guidance which advocates ‘loose tipping’ as the best method of ground preparation for a woodland or forestry after-use on sites reclaimed after dereliction or mineral extraction.

Abstract: Thesis (M.S.)--Humboldt State University, Natural Resources, Rangeland Resources and Wildland Soils, 2006

Abstract: The objective of this research was to evaluate compaction of a Red-Yellow Latosol subjected to forestry traffic including two types of skidder: a wheeled-clambunk skidder and a tracked one. This study tries to remedy the lack of information on this subject, considering that mechanized traffic can result in several impacts on the environment. These impacts are related to soil compaction and water resources quality, resulting in reduction of forestry productivity. The soil physical parameters analysed were: soil dry bulk density, total porosity and soil penetrometer resistance. A 2x3x3 factorial statistical design was used, including type of skidder, pattern operation and soil depth, using the Dunnet test at 5% significance level. The statistical analysis included the test of interaction between types of machines and the number of machine travels. Results showed that the loaded wheeled-clambunk skidder traveling once or twice caused effects of compaction on soil up to 15 cm depth. In the same condition, the tracked-skidder traveling twice also produced significant effect on soil compaction. In the 15-50 cm depth, only two travels of the wheeled-clambunk skidder caused soil compaction.