Abstract: Disturbances caused by timber harvesting have critical long-term effects on the forest soil microbiota and alter fundamental ecosystem services provided by these communities. This study assessed the effects of organic matter removal and soil compaction on microbial community structures in different soil horizons 13 years after timber harvesting at the long-term soil productivity site at Skulow Lake, British Columbia. A harvested stand was compared with an unmanaged forest stand. Ribosomal intergenic spacer profiles of bacteria, archaea and eukarya indicated significantly different community structures in the upper three soil horizons of the two stands, with differences decreasing with depth. Large-scale sequencing of the ribosomal intergenic spacers coupled to small-subunit ribosomal RNA genes allowed taxonomic identification of major microbial phylotypes affected by harvesting or varying among soil horizons. Actinobacteria and Gemmatimonadetes were the predominant phylotypes in the bacterial profiles, with the relative abundance of these groups highest in the unmanaged stand, particularly in the deeper soil horizons. Predominant eukaryal phylotypes were mainly assigned to known mycorrhizal and saprotrophic species of Basidiomycetes and Ascomycetes. Harvesting affected Basidiomycetes to a minor degree but had stronger effects on some Ascomycetes. Archaeal profiles had low diversity with only a few predominant crenarchaeal phylotypes whose abundance appeared to increase with depth. Detection of these effects 13 years after harvesting may indicate a long-term change in processes mediated by the microbial community with important consequences for forest productivity. These effects warrant more comprehensive investigation of the effects of harvesting on the structure of forest soil microbial communities and the functional consequences.

Abstract: This study presents the application of different methods (simple–multiple analysis and artificial neural networks) for the estimation of the compaction parameters (maximum dry unit weight and optimum moisture content) from classification properties of the soils. Compaction parameters can only be defined experimentally by Proctor tests. The data collected from the dams in some areas of Nigde (Turkey) were used for the estimation of soil compaction parameters. Regression analysis and artificial neural network estimation indicated strong correlations (r 2 = 0.70–0.95) between the compaction parameters and soil classification properties. It has been shown that the correlation equations obtained as a result of regression analyses are in satisfactory agreement with the test results. It is recommended that the proposed correlations will be useful for a preliminary design of a project where there is a financial limitation and limited time.

Abstract: Compared with traditional cropping systems, integrated crop—livestock systems have shown greater efficiency in improving soil quality and crop yield. The objective of this study was to determine how an integrated crop-livestock system affected soil properties and corn (Zea mays L.) yield when compared with continuous corn (CC). The study was conducted from 2004-2008 on a large-scale research farm located near Pana, IL, USA. We evaluated the following soil and crop variables: soil organic matter (SOM) fractions, total nitrogen (TN) and total organic carbon (TC), soil microbial biomass carbon (SMBC), water aggregate stability, soil penetration resistance (PR), and corn yield. Three treatments were used in this study: winter cover crops (WCCs) and cool-season pastures (CSP), considered integrated system treatments and a nonintegrated CC monoculture. In the integrated system, CSP and WCC treatments combined, had significantly higher TN (P = 0.0926) than CC. Water aggregate stability was also higher in the integrated system (P = 0.0039). Greater percentages of TC and TN were represented by particulate organic matter (POM) POM-N and POM-C in the WCC treatment, followed by CSP, and CC. The PR for CSP (928 kPa) was not significantly different than WCC (921 kPa). However, both were significantly different than CC (655 kPa). Averaged across years, corn grain yield for WCC (11.5 Mg ha -1 ) was significantly higher than CC (10.8 Mg ha -1 ) (P = 0.0780). These results confirm that WCC and CSP used within integrated crop-livestock systems should improve soil quality, SOM dynamics, and crop yield despite moderate soil compaction caused from cattle presence.

Abstract: A field experiment was conducted during 2003–2005 and 2004–2006 at the Indian Institute of Sugarcane Research, Lucknow, India to study the effect of Trichoderma viride inoculation in ratoon sugarcane with three trash management practices, i.e. trash mulching, trash burning and trash removal. Trichoderma inoculation with trash mulch increased soil organic carbon and phosphorus (P) content by 5.08 Mg ha−1 and 11.7 kg ha−1 over their initial contents of 15.75 Mg ha−1 and 12.5 kg ha−1, respectively. Soil compaction evaluated as bulk density in 0- to 15-cm soil layer, increased from 1.48 Mg m−3 at ratoon initiation (in April) to 1.53 Mg m−3 at harvest (in December) due to trash burning and from 1.42 Mg m−3 at ratoon initiation (in April) to 1.48 Mg m−3 at harvest (in December) due to trash mulching. The soil basal respiration was the highest during tillering phase and then decreased gradually, thereafter with the advancement of crop growth. On an average, at all the stages of crop growth, Trichoderma inoculation increased the soil basal respiration over no inoculation. Soil microbial biomass increased in all plots except in the plots of trash burning/removal without Trichoderma inoculation. The maximum increase (40 mg C kg−1 soil) in soil microbial biomass C, however, was observed in the plots of trash mulch with Trichoderma inoculation treatment which also recorded the highest uptake of nutrient and cane yield. On an average, Trichoderma inoculation with trash mulch increased N, P and K uptake by 15.9, 4.68 and 23.6 kg ha−1, respectively, over uninoculated condition. The cane yield was increased by 12.8 Mg ha−1 with trash mulch + Trichoderma over trash removal without Trichoderma. Upon degradation, trash mulch served as a source of energy for enhanced multiplication of soil bacteria and fungi and provided suitable niche for plant–microbe interaction.

Abstract: The initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. In the other hand on freshly tilled soils, traffic causes significant increments in soil compaction. The aim of this paper was to quantify the interaction of the soil cone index and rut depth induced by traffic of two different weight tractors in two tillage regimes: (a) soil with 10 years under direct sowing system and (b) soil historically worked in conventional tillage system. Treatments included five different traffic frequencies (0, 1, 3, 5 and 10 passes repeatedly on the same track). The work was performed in the South of the Rolling Pampa region, Buenos Aires State, Argentina at 34°55′S, 57°57′W. Variables measured were (1) cone index in the 0–600 mm depth profile and (2) rut depth. Tyre sizes and rut depth/tyre width ratio are particularly important respect to compaction produced in the soil for different number of passes. Until five passes of tractor (2WD), ground pressure is responsible of the topsoil compaction. Until five passes the tyre with low rut depth/tyre width ratio reduced topsoil compaction. Finally, the farmer should pay attention to the axle load, the tyre size and the soil water content at the traffic moment.

Abstract: Reduced soil porosity, water content, forest floor mass and rutting are four common disturbances during timber harvesting and skidding. The present study was conducted to evaluate effects of skid trail slope and traffic frequency on soil disturbance in a temperate mountainous forest. Four levels of traffic (3, 7, 14 and 20 passes of a rubber skidder HSM 904), and three levels of slopes (gentle 20%) were applied in three replicates consequently, 36 plots with 10 m long by 4 m wide were utilized in the study. All samples were taken from four randomized 4 m-transects in each plot across the wheel track perpendicular to the direction of travel with 2 m buffer zone between lines to avoid interactions. Results showed that during skidding total porosity, soil water and Forest floor decreased significantly ( P ≤ 0.05). Average total porosity on the treatments of >20% slope reduced significantly ( P ≤ 0.05) in comparison with those of 20% and 14 passes by soil compaction. Soil water content was decreased up to 45% after skidding in comparison with undisturbed area. There was a negative correlation between water content and skid trail slope. The forest floor mass decreased on steep trail during skidding in all traffics. The amount of forest floor mass on the treatments under the 7 passes and slopes of >20% treatments (437.6 kg ha −1 ) was significantly ( P ≤ 0.05) lower than those under the 14 passes and slopes of −1 ). Rut depth were recorded in 14 passes and increased with slope (18 cm 20%). In 3 passes, increase of skid trail slope from 10% to 20% corresponded to a decrease of 15%, 22%, and 67% in total porosity, water content and forest floor mass, respectively. The results indicated that slope steepness had a strong effect on the soil physical properties. In the present study, the skidder extracted different volume of logs during skidding operation. In order to obtain better interpretation the skidder must carry a fixed load during operation.

Abstract: Triticale and maize, with different structure of the root system and type of photosynthesis were examined to know changes in shoot physiology and root architecture in response to varying degree of soil compaction. In the root-box, effects of different levels of soil compaction (1.30, 1.47 and 1.58 Mg m -3 ) on a shoot and root dry matter, leaf number and area, number and length of seminal, seminal adventitious, nodal and lateral roots, leaf water potential (ψ), maximum quantum yield of PS II (Fv/Fm) and gas exchange were studied. Severe soil compaction treatments decreased leaf number, leaf area and dry matter of shoots and roots, while increasing shoot-to-root dry matter ratio. In addition, high level of soil compaction strongly affected the length of seminal and seminal adventitious roots, and the number and length of lateral roots developed on the seminal root. Along with the restriction of root growth, significant influences were observed in ψ, Fv/Fm and gas exchange. High soil compaction treatments resulted in decreased ψ, Fv/Fm, and photosynthetic rate, transpiration rate and stomatal conductance for both triticale and maize. Maize whose root growth was more heavily restricted by the soil compaction compared to triticale showed greater damages in physiological characteristics in leaves, while the impact on triticale was relatively small. The results indicated that damages in photosynthesis, water relation and shoot growth by soil compaction would be closely related to sensitivity of root systems architecture to high mechanical impedance of soil.

Abstract: Generally, soil compaction is a stress factor affecting negatively the plant growth, but its effects vary between species and with the soil compaction range. The objective of this study is to know the different growth responses of 17 woody species subjected to moderate soil compaction, because most of the studies about this subject compare the effects in treatments with a wide and discrete compaction range. We explore the effects of moderate soil compaction on a continuous scale (0.1–1.0 MPa) on seedling growth. Seedlings of 17 woody species (deciduous and evergreens) mainly from Mediterranean ecosystems were grown in near optimal conditions (light, temperature and water) in a greenhouse with a sandy substrate. In general, there was a great variability of the responses depending on the species and the studied variable. About 53% of the species showed a higher total biomass with a moderate increase in soil compaction possibly being due to a greater root–soil contact. In the same way, 41% of species increase the relative growth rate and 35% the total area. Nevertheless, in spite of these positive effects on growth, for some species (23%) there was a decrease in the root proportion with soil resistance, as result of soil strength. These effects of moderate soil compaction could sum up in two general responses of woody plants: growth increment and architecture distortion. This might be relevant as a lower root investment may be a disadvantage under drought conditions. Finally, a simple conceptual model is proposed to understand the general effects of soil compaction on growth and biomass allocation.

Abstract: Summary Grassland covers large areas at the treeline of the Alps, but management effects on the amount, distribution and turnover of soil organic matter (SOM) in this region are largely unknown. Our aim was to elucidate such effects for two management types using soil fractionation in combination with radiocarbon dating. Two Swiss grasslands sites at approximately 2020 m elevation (MAT +2.2°C, MAP 1050 mm) were used, which were hay meadows until 60 years ago when one was changed to grazed pasture. The sites are located in close vicinity to each other and have similar climate and parent material. Soils at each site were shallow (maximum 20 cm) and had high stone contents and thus a limited carbon (C) storage capacity. Total soil organic carbon (SOC) stocks in the two soils were similar (6.11 ± 0.69 and 6.07 ± 0.91 kg C m−2, respectively), as were proportions of readily available SOC and Q10 values measured by means of respiration in the laboratory. Grazing caused lower soil nutrient contents and slight soil compaction. Carbon in labile fractions and its radiocarbon age were particularly useful to distinguish management effects. Significantly more SOC was located in the pasture topsoil (0–4 cm) with a higher share of particulate organic C. Particulate and microaggregate-associated C was slightly younger under pasture, indicating incorporation of recent plant tissue by cattle. At both sites, 14C-derived mean residence times of SOC increased in the order particulate < micro-aggregate < silt and clay-associated matter and were greater below 4 cm than in the topsoil. Age differences in old silt and clay C could not be attributed entirely to management effects. We discuss pitfalls for turnover estimates of bulk soils introduced by choosing non-unique fractions. Together, the data suggest that a change from haying to cattle grazing may cause a strong decoupling of microbial processes within the soil’s architecture and that in such ecosystems SOM under pastures may be more vulnerable to environmental disturbances.

Abstract: Improper cropping and overgrazing have led to land degradation in semi-arid regions, resulting in desertification. During desertification, vegetation changes have been widely observed, and are likely controlled to some extent by soil water. The purpose of this study was to investigate changes in soil physical properties, organic C, and vegetation induced by land-use changes, with special reference to the dynamics of available soil water. We selected four study sites in a typical Mongolian steppe grassland: grassland protected from grazing, grazed grassland, abandoned cropland, and cultivated cropland. Grazing exclusion increased the cover of perennial grass, with little increase in the root weight. Since there was no difference in available water between the grasslands with and without grazing, there appears to be no serious soil compaction due to overgrazing. On the other hand, vegetation cover and the number of species were poor in both abandoned cropland and cultivated cropland. However, the root weight was greater in abandoned cropland. Although the abandonment of cultivation appeared to increase organic C, available water did not differ significantly in comparison with cultivated cropland. The silt contents were significantly lower in abandoned and cultivated cropland than in both grasslands, suggesting the effects of wind erosion. In addition, the silt contents were positively correlated with the volume fraction of storage pores for available water. Therefore, the lower silt contents may constrain the volume of available water in abandoned cropland. Moreover, the unsaturated hydraulic conductivity results indicated that the diameters of storage pores for available water at the present study sites were smaller than those suggested by previous studies. Although the differences in vegetation cover by different land-use types were observed at every site, differences in the volume of available water were observed at between abandoned cropland and cultivated cropland. The reason why the no differences in available water between grazed grassland and grasslands protected from grazing may be short time of grazing exclusion for 2 years for evaluating the effects of exclusion on soil properties.

Abstract: In this study, strength attributes and compaction susceptibility of the main classes of Brazilian Latosols (Oxisols), under native vegetation, were studied using the load bearing capacity models relating precompression stress, compression index and water potential through statistical regression models. These models were developed based on the results of the analysis of undisturbed soil samples collected at the B horizon at the different sites. The results showed that the maximum value of the compression index was 0.53 for the Acric Red Latosol, indicating its higher susceptibility to soil compaction. The Dystrocohesive Yellow Latosol had the highest load bearing capacity, while the Acric Red Latosol had the lowest one. The Dystrocohesive Yellow Latosol due to its high load bearing capacity and bulk density (mechanical resistance) behave similarly to hardsetting soil, in which the plants root system has severe physical restrictions to explore deeper horizons during the dry periods. Differences in the load bearing capacity and compaction susceptibility were found to be influenced by soil structure which is associated with clay mineralogy in these very weathered-leached soils and water potential. The study also showed that soil compression index is influenced by water potential and clay mineralogy also. Our work has laid a foundation for estimation of compaction susceptibility of Latosols.

Abstract: The small-scale effects of plant morphology in improving soil quality and reducing runoff and soil loss have remained unclear, especially in some arid environments with sparse vegetation. We selected three representative species with contrasting morphologies (Artemisia gmelinii; Ajania potaninii; Pulicaria chrysantha) to examine the effects of plant morphology on soil quality, runoff, and soil loss in the dry-warm river valley of the upper reach of Minjiang River, SW China. Runoff events were monitored from July through October 2006 using runoff plots on a micro scale (<40 × 40 cm2) on a south-facing slope. The observation duration for rainfall and runoff events can be divided into two stages. Higher runoff depth, but lower soil loss per event occurred at the second stage as compared with the first stage due to the differences in rainfall, plant, and soil surface characteristics. The two herbs, A. gmelinii and P. chrysantha, had greater improvements on soil quality yielding high soil nutrient content and low soil compactness, while the effectiveness of the small shrub, A. potaninii, was minimal. Relative to bare surface (control treatment), the effectiveness of reducing runoff depth per event was 64.9, 66.6 and 38.0%, and reducing soil loss 65.5, 59.3 and 69.9% for A. gmelinii, A. potaninii, and P. chrysantha, respectively. All three plant species can improve soil quality and reduce runoff and soil loss, but their effects vary, which implies that plant morphology has to be considered while selecting species for ecosystem restoration.

Abstract: This study had as objective to evaluate the effects of crops succession and rotation on physical properties and crops yield on an Oxisol (clayey Haplortox) under no-tillage system, in Rio Grande do Sul State, Brazil. The treatments included four cropping sequences, used from 1998 to 2001: 1) succession wheat / soybean, 2) rotation corn / oat / corn+ Cajanus cajan L. Millsp / wheat / soybean / wheat, 3) rotation Cajanus cajan L. Millsp / wheat / soybean / wheat / soybean / oat, and 4) rotation Crotalaria juncea L. / wheat / soybean / oat / corn / wheat. In October of 2000 and 2001, soil samples were collected to determine physical properties. In all years, the crops yield was measured. The Oxisol cultivated under notillage had a high compaction degree, with soil bulk density greater and macroporosity smaller than the critical limit for clay texture. The largest limitations were observed below the layer of 0 to 0,03m, because in the uppermost layer soil mobilization by successive operations of fertilization and sowing increases soil porosity and reduces soil density. Thus, greater volume of pores is observed between soil saturation and field capacity, responsible for soil aeration, and between field capacity and wilting point, responsible for storage of plant available water. The use of cover crops once every three years was not efficient to reduce soil compaction. The yield of the subsequent crops was influenced positively in the rotation with Crotalaria juncea, while the other cropping systems did not differ from crop succession.

Abstract: There is a growing demand for the estimation of load support capacity of soils on a larger scale in mitigating compaction and other degradation forms of agricultural soils. In this study, we examined the relationship between load support capacity and soil mineralogy, using four latosol (oxisol) types. Our results showed that soil color could be used as a first discriminator of load support capacity in latosols. Hematitic (reddish) latosols were observed to have lower load support capacity when compared to the goethitic (yellowish) soils. We observed that the clay mineralogy is associated with soil structure development and consequently with the load support capacity of the soil. Our study has laid a foundation for large-scale estimation of strength attributes in latosols indicated by their structure, which is associated with their quite stable and simple mineralogy.

Abstract: Most agricultural land has been compacted to some degree by heavy machinery or livestock trampling. This legacy is expected to influence the success of tree seedling recruits in farmland areas where natural regeneration is being encouraged. We investigated the impact of soil compaction on seedlings of a woodland eucalypt (Eucalyptus albens) and an annual grass competitor (Vulpia myuros) in a laboratory experiment. Replicate soil cores were created at five bulk density levels; 1.0, 1.1, 1.2, 1.3 or 1.4 Mg m−3 with a soil water content of 20%. The depth of root penetration declined linearly with increasing bulk density, resulting in a decrease in root depth of around 75% in the most compacted soil compared with the least compacted soil for both species. Shoot length and primary root length did not vary between soil bulk density levels for either species, but seedlings responded to increasing levels of compaction with oblique (non-vertical) root growth. Results suggest that young seedlings of both E. albens and V. myuros will be more susceptible to surface drying in compacted than uncompacted soils and therefore face a greater risk of desiccation during the critical months following germination. Any competitive advantage that V. myuros may have over E. albens is not evident in differential response to soil compaction.

Abstract: Effects of soil compaction, organic matter removal, and rehabilitation on lodgepole pine (Pinus contorta Dougl. ex. Loud.) and Douglas-fir (Pseudotsuga menziesii var. menziesii) were studied after three growing seasons in a long-term soil productivity study established on three calcareous soils in southeastern British Columbia. Effects of soil compaction and organic matter removal on tree growth were site and species specific. Moderate soil compaction increased the diameter and height increment of both species within the stem-only harvest treatment on all three sites, particularly at the coarser textured site (Emily Creek). Compaction tended to reduce tree mortality. Growth of both species was reduced by forest floor removal in the noncompacted soil at Mud Creek and Emily Creek and by whole-tree harvest in the moderately compacted soil at Mud Creek and Kootenay East, possibly due to treatment-induced water limitation. Whole-tree harvest and forest floor removal stimulated lodgepole pine and Douglas-fir growth in the noncompacted soil at Kootenay East. The rehabilitation treatment (established by tilling a heavily compacted soil) reduced lodgepole pine tree mortality on all sites and increased rootcollar diameter and height increment at Mud Creek and Kootenay East. Our findings may provide early growth indication and help assess long-term tree growth trends at these and other long-term soil productivity or related sites.

Abstract: The specific objectives of this research were to quantify the effects of certain environmental factors on the relative strength loss of soil—cement subjected to compaction delay and to develop a numerical tool that can be easily used by engineers and contractors for determining a maximum compaction delay time for a given project. These objectives were addressed through extensive laboratory work and statistical analyses. The laboratory work involved testing an aggregate base material and a subgrade soil, each treated with two levels of cement. Environmental factors included in the experimentation were wind speed, air temperature, and relative humidity; three levels of each factor were evaluated in combination with three compaction delay times. The primary response variables in this research were relative compaction and relative strength. The findings indicate that relative strength is sensitive to variability among the selected independent variables within the ranges investigated in this research, while re...

Abstract: Testing rehabilitation strategies for arid rangelands: Overgrazing by domestic cattle has caused loss of plant diversity and primary productivity in rangelands of the Arid Chaco (Argentina). The objective of our study was to evaluate a number of rehabilitation strategies that might increase the density of forage grasses in an overgrazed rangeland in this region. Based on the hypothesis that soil compaction, lack of seeds and litter cover constrain plant establishment we performed a field factorial experiment, that combined soil pitting, seed addition and the combined effect of competition release and litter addition. During four years, we evaluated seedling and plant density of added grasses and all forage grasses. Seed addition was the only factor that increased seedling and plant density, with Pappophorum spp. and P. philippianum accounting for the main variation in seedling and plant density, respectively. During the third year (a dry year), there was 70-80% decrease in plant density in all treatments, although the differences due to the addition of seeds was still apparent. Our results suggest that, in addition to adverse climatic conditions, the lack of seeds in the soil bank restricts the recovery of overgrazed rangelands in the Arid Chaco. Pappophorum philippianum seems to be a promising species for the rehabilitation of these rangelands.

Abstract: At the paramo El Granizo (Colombia), strategic for the capital district because of its hydric regulation and actually dedicated in a high percent to agricultural activities and cattle raising, an exploratory study was performed. The purpose of the research was to determine the effect caused by these activities on some physical and chemical soil characteristics. As references, areas without traces of human actions, areas with agricultural performances and / or livestock and areas in a resting period, were evaluated. It was proven that the agricultural practices cause negative effects on the soil characteristics of the paramo. As consequences, soil compaction, increase of bulk density and the decrease of moisture retention, stand out. In reference to the altered chemical properties, it was detected that the levels of nitrogen, of phosphor and the relation of bases were altered, influencing negatively the paramo´s natural conditions. In general it was observed that the augmentation of the farming frontier at the paramo makes that the soil is compacted in some cases and, in others, eroded and that the water retention, its main function, decreases, causing the well known negative consequences.

Abstract: Nacrtak Extracting logs from stump to landings causes extensive damages to forest stand and soil. In this research two parcels adjacent to each other were selected in order to assess the effect of traditional and mechanized methods of logging on regeneration and soil compaction. A skid trail and a mule trail with similar longitudinal slope, skidding direction and total volume of extracted wood were chosen in the parcels. The cylindrical sampling method was used to determine wet and dry soil bulk density and the samples were taken at 0–10 cm and 10–20 cm depth from skid and mule trails. The results showed that soil dry bulk density increase in skid and mule trails compared to control at 0–10 and 10–20 cm depth, was significant (p<0.01). This increase in mule trail at 0–10 cm depth was significantly higher than at 10–20 cm depth (p<0.01), but percentage of soil dry bulk density increase compared to control in skid trail at 0–10 cm and 10–20 cm depths was not significantly different. Soil dry bulk density increase compared to control at 0–10 cm depth of mule trail is higher than skid trail, but at 10–20 cm depth the skid trail is higher than mule trail. Systematic random sampling method was used to determine damages to different regeneration groups due to logging operations. The results showed that damages to each regeneration group seedling and small sapling in mule logging method were significantly lower than mechanized logging method.

Abstract: Some forms of soil compaction occur on arable lands both in Hungary (1.82 million ha) and in Croatia (0.97 million ha) having negative impacts on agricultural production. Tillage-induced subsoil compaction has oft en occurred in the Pannonian region in relation to traffi c-induced compaction. Soil compaction has become a soil management problem during the last decade as a result of the occurrence of periods of water-logging as well as droughts. Th is study contains an evaluation of factors relating to subsoil compaction, as indicator of climate eff ects on arable fi elds. Th is paper is based on soil condition monitoring and measuring that was started 32 years ago and on short and long-term experiments modelling and checking the extension of compaction in the soil. Th e survey comprised 1526 monitoring places and 38 experimental plots. Th e following fi ve points were chosen for monitoring: 1) root zone state (to a depth of 0-60 cm); 2) occurrence of compacted layer (indicating likelihood of risk); 3) extension of the compacted layer (indicating the degree of damage); 4) long term eff ects of tillage (soil state deterioration or improvement), and 5) tillage-induced water-logging and drought damage impacts on yield loss. Th e main objectives of the experiments were: 1) occurrence and the extent of tillage-pan damage in soils of diff erent susceptibility to compaction; 2) consequences on water management in each of the years covered by the experiments; 3) soil quality consequences, and 4) alleviation of pan-compaction by mechanical and biological methods. Long-term fi eld monitoring and experimental work have both convincingly proven a correlation between subsoil compaction and the degree of climatic damage. In view of the fi ndings, trends in soil tillage can be grouped into the following two categories: climate damage mitigating and climate-stress increasing ones. Th e formation and location of compacted layers provided information concerning the depth, the method and the type of tillage applied, along with the expected risk for crop production under extreme climate conditions.

Abstract: The soil compaction promoted for animal trampling and traffic of machines, is one of great impediments to attainment of raised pasture productivities. However, the soil-pasture relationship studies have not taken in consideration the biological soil descompaction, as well as its effect in productivity. This study objective was to evaluate dry mass production of Tifton 85 grass in function of different soil compaction degrees and potential of structural quality recovery of an Red-Yellow Argisol, promoted by forage plant. The experiment was carried out in green house, in delineation entirely randomized, with the tifton 85 grass crop in the following degrees of compacting: 64%, 84%, 90%, 93% and 100%, gotten for the assay of Normal Proctor. The attributes had been evaluated the soil physical- hydric, least limiting water range and forage dry mass production. Tifton 85 grass recovered the structure of Red-Yellow Argisol. The soil descompaction promoted adequate soil biophysics conditions to forage development. The dry mass production increased with the cutting succession independent of initial degree of soil compaction. KEY WORDS: Biological soil descompaction, Cynodon sp., least limiting water range, recovery of pastures.

Abstract: The compaction process can promote changes in the physical attributes of soil, to the point of limiting the genetic potential for the development of more sensitive agricultural crops or cultivars. The goal of this study was to evaluate, on a clayed Red Latosol (Oxisol), the response of production parameters of different varieties of soybean ( Glycine max ) and physical attributes of soil under tillage farming, and with additional compression. The study was conducted at C-Valley Agroindustrial Cooperative, in Palotina (Parana State). Two treatments of soil were evaluated: no-tillage without additional compaction (PD-C0) and no-tillage with additional compaction (PD-C1), and five varieties of soybeans: (1) Coodetec 204, (2) Coodetec 215, (3) Monsoy 5942, (4) Embrapa 48 and (5) Spring. A completely randomized experimental design in a 5 x 2 factorial scheme was adopted. The attributes of soil evaluated were: bulk density, total porosity, macro- and microporosity. In the plants, the following parameters were assessed: harvesting dates, plant height, height of insertion of the first pod, mass of one thousand grains and productivity. The results showed that the parameters for the production of soybean cultivars were not influenced by the different levels of soil compaction, and the differences observed were due to the characteristics of the cultivars themselves.

Abstract: This paper reports sheep camping influences on soil chemical and physical properties, and pasture dry matter (DM) production of an acidic soil on the southwest slopes of New South Wales, Australia. The experiment was conducted in the spring (October-November) of 2005 on a long-term field experimental site after 13 yr of rotational grazing. The factors considered were sheep camping (distance from the camping site), pasture type (perennial vs. annual pastures) and lime application (limed vs. unlimed treatments). Over 13 yr of rotational grazing, significant amounts of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) were deposited near the sheep camping site via the deposition of animal excreta. Total C increased from 32.8 g kg-1 20 m away from the camping site to 41.9 g kg-1 at the camping site in 0-5 cm soil depth. The Colwell P increased from 44.0 to 125.9 mg kg-1 from the non-camping area to the camping site in 0-5 cm soil depth. The most interesting result from the current study is that soil ...