Abstract: Compaction characteristics of soils being very important from field application point of view, any attempt to develop correlation equation to predict the same should be rational and universally applicable. It has been reported in the literature that the plastic limit of soils bear a good correlation with their compaction characteristics. In this study, attempts have been made to use modified plastic limit to account for the proportion of fraction less than 425 μm as a parameter to correlate with the compaction characteristics of natural soils. The proposed correlation between the compaction characteristics of natural soils with their modified plastic are going to be handy tool for construction engineers in quickly assessing their suitability for compaction related purposes.

Abstract: 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.

Abstract: We evaluated effects of topsoil scarification by heavy machinery on growth of two valuable, shade-intolerant tree species — Nothofagus dombeyi (Mirb.) Oerst. (evergreen and considered to be very pl...

Abstract: Row crops such as potatoes (Solanum tuberosum L.) and carrots (Daucus carota L.) are of high economic value in the Nordic countries. Their production is becoming more and more specialized, including continuous arable cropping and heavier farm machinery, with increased risk of soil compaction. The result may be restricted root development and economic losses. Potatoes have widely branched adventitious roots, whereas carrots have taproots with fibrous roots extending from them. Under optimal soil conditions, total root length per surface area may reach more than 10 km m−2 for both species. Maximal root depth is about 140 cm for potato and more than 200 cm in carrots. Most of the root mass is usually distributed within the upper 100 cm, whereof more than 50% may be deeper than 30 cm. Soil compaction causes a dense soil with few large pores, poor drainage and reduced aeration, especially in wet soils with low organic matter content and high proportions of silt or clay. With compacted subsoil layers, roots wil...

Abstract: Aim of study: The primary objective of this paper was to compare the effects of different types of forestry machine chassis on the compaction of the top layers of soil and to define the soil moisture content level, at which machine traffic results in maximum compaction.Area of study: Measurements were conducted in eight forest stands located in Slovakia and the Czech Republic. The soil types in the stands subjected to the study were luvisols, stagnosols, cambisols, and rendzinas.Material and Methods: The measurements were focused on tracked and wheeled (equipped with low pressure tyres) cut-to-length machines, and skidders equipped with wide and standard tyres. The bulk density of soil was determined from soil samples extracted from the ruts, the centre of the skid trail, and the undisturbed stand. To determine soil moisture content, at which the soil is the most susceptible to compaction, the Proctor standard test was employed.Main results: The moisture content for maximal compaction fluctuated from 12% to 34.06%. Wheeled machines compacted the soil to 1.24 – 1.36 g.cm-3 (30.3 – 35.4 % compaction) in dried state. Bulk density of soil in stands where tracked machine operated was lower, ranging from 1.02 to 1.06 g.cm-3 (25.3 % compaction).Research highlights: All wheeled machines caused the same amount of soil compaction in the ruts, despite differences in tyres, machine weight, etc. Maximum compaction caused by forestry machines occurred at minimal moisture contents, easily achievable in European climatic conditions. Keywords: soil compaction; bulk density; soil moisture content limits; cut-to-length machines; skidders.

Abstract: Land subsidence is a worldwide problem that is typically caused by human activities, primarily the removal of groundwater. In Western Taiwan, groundwater has been pumped for industrial, residential, agricultural, and aquacultural uses for over 40 years. In this study, a multisensor monitoring system comprising GPS stations, leveling surveys, monitoring wells, and Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) was employed to monitor land subsidence in Western Taiwan. The results indicate that land subsidence in Yunlin County was mainly affected by the compaction of subsurface soils and over-pumping of groundwater from deep soils. The study area comprised western foothills, characterized by sediments containing predominantly gravel, and coastal areas, where clay was predominant. The subsidence in coastal areas was more severe than that in the western foothills, as a result of groundwater removal. An additional factor affecting subsidence was the compaction of deep layers caused by deep groundwater removal and the deep-layer compaction was difficult to recover. Based on multisensor monitoring results, severe subsidence is mainly affected by compaction of subsurface soils, over-pumping of groundwater from deep soils, and deep soil compaction.

Abstract: Urbanization converts animal habitats into globally homogeneous environments. Consequently, urban communities have low diversity and are often dominated by a few species. However, proximate environmental factor(s) causing community degradation have rarely been identified among diverse and co-varying urban parameters. The present study addresses the recent loss of cicada diversity in Osaka, Japan, where cicada communities are overwhelmed by a single species, Cryptotympana facialis. A field survey across an urban-forest gradient revealed that the trend of decreasing cicada diversity toward the urban core was mostly associated with the soil hardness among the environmental variables examined. Simultaneously, the proportion of C. facialis increased with soil hardness, although this effect was partially mitigated in forest patches. Newly hatched nymphs of C. facialis exhibited greater burrowing ability than that in other native species. These findings identify soil compaction due to urbanization as a possible cause of cicada diversity loss, as it impedes the passage of nymphs to underground nests. This impact of urban soil compaction may influence ecosystem functioning of soil-dwelling arthropods and their trophically associated animals.

Abstract: Because groundwater is Earth's largest pool of freshwater, understanding the sensitivity of deep drainage to climate, soils, and land cover is critical in managing water resources. To better understand controls on this critical flux in the context of woody encroachment, we determined the sensitivity of deep drainage to climate, soil texture, soil compaction, rooting depth, growing season duration, and plant–water stress response using Hydrus-1D to simulate deep drainage. To evaluate the simulation results, we compared these results with ground measurements at two anchor sites. At both anchor sites, Hydrus-1D predictions of deep drainage matched measured values within the errors inherent in ground measurements. Sensitivity analysis suggested greatest sensitivity of deep drainage to climate (24 mm yr−1) and rooting depth (12 mm yr−1), moderate sensitivity to growing season duration (5 mm yr−1) and soil texture (4 mm yr−1), and lowest sensitivity to topsoil compaction and plant–water stress response (3 mm yr−1). The sensitivity analysis indicated the relative importance of the plant-related factors considered, which, in decreasing order, were rooting depth, growing season duration, and plant–water stress response – factors that change concomitantly as a result of forestation or woody encroachment. Further ground-truth measurements of woody encroachment effects on deep drainage are needed to confirm or refine the results of this simulation modelling study. Copyright © 2015 John Wiley & Sons, Ltd.

Abstract: Accurate measurements of soil stress are needed to evaluate the impact of traffic on soil properties and prevent soil compaction. Four types of transducer commonly used to measure vertical stress were calibrated in realistic traffic conditions in the field. The four transducer types differed in shape and dimensions, which are important factors influencing stress. Deviation of measured stress from true stress ranged from 15% underestimation to 18% overestimation, with transducer thickness to width ratio being the most important shape factor influencing the stress recorded. Changes in physical conditions in the soil above the transducers due to their installation did not influence the accuracy of vertical stress measurements. The results of this calibration are valid for correcting stress measurements in topsoil, but should be used with caution for vertical stress measurements in subsoil. All stress transducers should be calibrated in field conditions before use. More research is needed to characterise the stress distribution in the measuring face of transducers and better predict interactions between transducer and soil during loading.

Abstract: Ouimet, R., Pion, A.-P. and Hebert, M. 2015. Long-term response of forest plantation productivity and soils to a single application of municipal biosolids. Can. J. Soil Sci. 95: 187–199. After 16 to 19 yr, we revisited four experimental trials set up in the early 1990s to evaluate the long-term impact of municipal biosolids applied in forest plantations. Tree growth and the soil were sampled to determine the effects of a single application of biosolids applied at (liquid equivalent) rates of 0, 130, 200, and 400 m3 ha−1. Tree radial growth responded markedly to biosolids in the young plantations, increasing from 18 % for Pinus resinosa to 62 % for Picea glauca, and up to 700 % for Quercus sp. Increases in phosphorus (P) concentrations in the tree foliage in response to biosolids could still be detected in the conifer trials. In the top 0–5 cm soil layer, organic carbon (C), total nitrogen (N), P, and copper (Cu) concentrations and pools increased, while soil compaction and bulk density decreased. In the d...

Abstract: The influence of vibration frequency was studied in 110 small-scale compaction tests conducted using a vertically oscillating plate. The underlying soil was dry sand, or sand close to the optimum water content. The results showed that there is a resonant amplification, providing a slightly higher degree of compaction. Frequency has a major influence on soil compaction. An iterative method for calculating the dynamic response of the plate, incorporating strain-dependent properties of the soil, is also presented. The calculated frequency response agrees fairly well with measured quantities.

Abstract: Increased runoff rates and volumes from urbanizing watersheds are generally attributed to increased imperviousness within the watershed. While pervious surfaces in urban areas are often credited with having little runoff contribution, soil compaction can reduce infiltration capacity, leading to increased runoff. The objective of the research reported in this paper was to evaluate the hydrologic response of potential treatments for mitigating urban soil compaction. In the lysimeter study of the research reported in this paper, two Florida soils [(1) Arredondo fine sand, and (2) Orangeburg fine sandy loam] were compacted and potential mitigating treatments were applied to evaluate runoff reduction. Treatments combined two incorporation depths [(1) 10 cm, and (2) 20 cm] with three amendment cases [(1) no amendment, (2) compost, and (3) fly ash] and were applied to both soils. A set of compacted lysimeters for each soil were designated as controls and remained compacted (no treatment) throughout the r...

Abstract: Anthropogenic disturbances frequently exceed resilience of riparian forests. In small-scale restoration projects revegetation is a common technique, but its success depends on the plant species used and some environmental filters. We investigated whether grass competition and soil compaction together with seasonal drought and flooding limit the establishment of seven tree species experimentally planted in abandoned riparian pastures in Southern Mexico. We tested the effects of grass clearing and soil tilling and analyzed seasonal variation of vertical distance to water level, and changes in tree performance, microclimate, and vegetation biomass after planting. Seedling survival was low (19 ± 3 %), ranging between 3 (Brosimum alicastrum, Moraceae) and 38 % (Pachira aquatica, Bombacaceae). Survival was negatively correlated to vertical distance to water level, highlighting the importance of the short but severe dry season that may occur in the humid tropics, which reduced survival by >60 %. Flooding events also produced high seedling mortality (80 % after the two first events). Clearing but not tilling enhanced seedling survival. Clearing also significantly increased seedling growth of some species, suggesting competition release. Tilling did not have any consistent effect on growth, but it appears to counteract the positive effects of clearing. Both pre-existing and planted trees ameliorated microclimate to produce better conditions for establishment of new trees following natural regeneration. We conclude that clearing can enhance seedling establishment in riparian abandoned tropical pastures, but other revegetation treatments intended to reduce soil drying and uprooting by flooding during early establishment should be evaluated to improve the cost-benefit of restoring riparian forest.

Abstract: Open-pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re-establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P < 0.05). In white spruce stands, fine root surface area was the only parameter that increased along the productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

Abstract: Energy saving was one of the main benefits of controlled traffic system. Research on the energy conservation mechanism of controlled traffic system with medium and small scale agricultural machinery was conducted in the North China Plain, to quantify the energy benefits of controlled traffic system. Two treatments were included: zero tillage with controlled traffic (NTCN) and zero tillage with random traffic (NT). Results showed that controlled traffic system can increase soil compaction in traffic lane and reduce soil compaction in crop zone. Controlled traffic system can reduced machinery field working force significantly through lower tire rolling resistance from relatively harder permanent track, and lower tine opener working resistance from softer soil in crop zone. Compared with NT, NTCN reduced traction force by 14.6%, 13.3% and 13.3% at subsoiling, wheat and maize no-till planting. Consequently, fuel consumption was reduced in all machine operation in controlled traffic system. Compared with NT, two years total fuel consumption in NTCN was significantly reduced by 19.79 L/ha (23.7%). Besides, controlled traffic increased total annual yield and WUE by compensating yield loss in winter wheat through the yield benefit in summer maize, even though 30% of the field was occupied by the permanent traffic lanes. Although these results were preliminary, it was indicated that controlled traffic system was fuel saving system in small and medium machinery condition in North China Plain.

Abstract: Soil compaction is a major threat to natural resources. However, little information is available on the impacts of soil compaction on arthropod diversity especially relative to different types of vegetation, land use and restoration activities. In response to this dearth of information, we studied soil compaction, as well as percentage soil moisture and mean leaf litter depth, associated with four vegetation types: natural vegetation (fynbos, the historic condition), agricultural land (vineyards), invasive alien trees, and vegetation cleared of invasive alien trees (recovering vegetation). Our study took place in the Cape Floristic Region, South Africa, a biodiversity hotspot, yet also an area of intense viticulture and heavy invasion by alien plants. We sampled soil surface-active arthropods using pitfall traps, and compared species richness and abundance in different vegetation types with various levels of soil compaction and other soil variables. Overall, vineyards had the highest soil compaction while natural fynbos and aliens had low and comparable compaction. For both arthropod species richness and abundance, the order of the four vegetation types was, from highest to lowest: natural fynbos, alien cleared sites, vineyards, and alien infested sites. Level of soil compaction negatively correlated with arthropod species richness but not with abundance. Neither soil moisture nor leaf litter depth on their own significantly affected arthropod species richness or abundance. While alien trees overall had a strong negative effect on both arthropod species richness and abundance, and much more so than vineyards, the situation is reversible, with removal of aliens being associated with rapid recovery of soil structure and of arthropod assemblages. This is an encouraging sign for restoration.

Abstract: In mechanized timber harvesting, it is common practice to build brush mats from logging residues on skid trails. Protective effects of brush mats against soil compaction are documented by several studies. On the other hand, a large quantity of nutrients is concentrated on the skid trail. Fully mechanized harvesting has been criticized frequently for this reallocation of nutri- ents. Is there really a risk of nutrient leaching below skid trails or imbalances? Are the nutrients redistributed through nutrient uptake by roots of adjacent trees? Effects of fully mechanized thinning on soil, water and nutrient balance were examined in a seventy years old spruce stand on a nutrient poor site in Bavaria. Sections of the trails were covered with brush mats, while other sections remained uncovered. For five replications, soil physical properties, soil chemistry, matter and water balances and the density of fine roots were measured in the middle of the trail, under the tire tracks, at the transition of trail and stand and inside the stand over a period of two years. Logging operation caused soil compaction. The macropore volume decreased and both hydraulic conductivity and air permeability were severely reduced. The nutrients were largely kept in the forest ecosystem. Results of the soil moisture monitoring indicate that, within the sections covered by a brush mat, tree roots extracted water from the soil between the tracks. Without cover, the trees scarcely extracted water from this area. Hence, building a brush mat can facilitate water availability and thus enable redistribution of nutrients.

Abstract: Ouimet, R., Pion, A.-P. and Hebert, M. 2015. Long-term response of forest plantation productivity and soils to a single application of municipal biosolids. Can. J. Soil Sci. 95: 187-199. After 16 to 19 yr, we revisited four experimental trials set up in the early 1990s to evaluate the long-term impact of municipal biosolids applied in forest plantations. Tree growth and the soil were sampled to determine the effects of a single application of biosolids applied at (liquid equivalent) rates of 0, 130, 200, and 400 m3 ha-1. Tree radial growth responded markedly to biosolids in the young plantations, increasing from 18 % for Pinus resinosa to 62 % for Picea glauca, and up to 700 % for Quercus sp. Increases in phosphorus (P) concentrations in the tree foliage in response to biosolids could still be detected in the conifer trials. In the top 0-5 cm soil layer, organic carbon (C), total nitrogen (N), P, and copper (Cu) concentrations and pools increased, while soil compaction and bulk density decreased. In the deepest soil layer sampled (20-40 cm depth), the total N and calcium (Ca) pools were reduced by the biosolids treatments, while the pool of exchangeable acidity increased. Our observations indicate that a single application of liquid biosolids up to 400 m3 ha-1 (30 t ha-1 DM) in young forest plantations is a sustainable practice without undue risk to such podzolic soils.

Abstract: This study examined the characteristics of heat and water transfer in structurally modified urban soils. To satisfy our goals, we measured the temperature and moisture content of anthropogenic soils to a depth of 50 cm. Field observations was carried out for three sets (each of two pedons) of soils in the Tokyo Metropolitan area. Each pedon had the same turf coverage but different profile modifications in the green areas. Soil temperature, soil moisture, and precipitation data were collected during the summer (July–Sept) and winter (Oct–Feb) every 10 min. From the results, we calculated the thermal diffusivity and thermal conductivity in each pedon. Soil temperature showed a clear daily variation down to 30 cm depth. Temperature transmission to deeper layers was faster in pedon having stronger soil compaction and more artificial fragments than in pedons with weaker soil compaction and fewer concrete fragments. This finding suggests that strongly compacted soil has a relatively high thermal conduct...