Soil Compaction after Increasing the Number of Wheeled Tractors Passes on Forest Soils in West Carpathians

Soil disturbance and compaction are inherent in ground-based harvesting operations. These changes are affected by numerous factors, related mainly to the technical parameters of the machines, soil conditions, and the technology used. This study aimed to analyze the changes of surface layers of soil caused by skidder traffic without loads on the Cambisols of Western Carpathians. We observed changes in the soil bulk density and penetration resistance. The results showed that only machine traffic caused a 0.32 to 0.35 (g cm−3) increase in soil bulk density. Besides machine traffic, bulk density was affected by soil moisture content. Penetration resistance of soil increased by 0.15 to 1.04 (MPa) after traffic of 40 machines. Penetration resistance showed a lower increase after traffic, and regression and correlation analysis proved a relationship between penetration resistance, skeleton content, and penetration depth, besides the number of machine passes (r = 0.33–0.55). Observing the changes in the physical properties of soils caused by machine traffic allows for a more detailed view of the effects of forest harvesting machinery on forest soils.

Effects of Breccia and Water Contents on the Mechanical Properties of Fault-core-zone Materials: an Experimental Investigation Using Artificial Specimens

Determining the mechanical properties of fault-core-zone materials is challenging because of the low strength of such materials, which affects field sampling, specimen preparation, and laboratory testing. We overcame this problem by preparing and testing mechanical properties of 132 artificial fault-core-zone specimens consisting of mixtures of breccia, sand, clay, and water. The unconfined compressive strength (UCS), elastic modulus (E), and penetration resistance value (PRV) of these fault-core-zone materials were measured, and the effects of breccia content and water content on mechanical properties were assessed. Results show that UCS is inversely proportional to breccia content and water content, and that E is inversely proportional to water content. Furthermore, the inverse relationship of UCS with water content varies with breccia content. UCS is proportional to both PRV and E, and the relationship for each varies with breccia content. High coefficients of determination (R2 = 0.62–0.88) between the parameters suggest that breccia content, water content, and PRV are potentially useful parameters for estimating the mechanical properties of fault core zones.

Properties of Shotcrete According to Accelerator Types and Mixing Ratios

Shotcrete should be attached to the ground and should have stable strength for a long-term. It should develop strength earlier for rapid work. Therefore, in this study, three types of accelerators—aluminate, cement mineral, and alkali-free—were selected and mixed to secure the initial strength. Depending on the type and mixing rate of each accelerator, slump, air amount, and compressive strength were used to evaluate the basic properties, boiling water absorption test, and chloride ion penetration resistance to conduct durability analysis. The mixing of aluminate-based and cement-mineral-based accelerators was effective in improving the initial strength, and alkali-free accelerator was effective in improving the long-term strength. The mixture to which accelerators were not mixed showed the highest water-tightness.

Ecomorphic Structure Transformation of Soil Macrofauna Amid Recreational Impact

The level of reacreation load on the components of urban green areas is increasing, so identifying the effective management tools in these ecosystems is becoming crucial for ensuring the maintenance of soil biota habitats. The purpose of this study is to reveal a pattern of structuring community of soil macrofauna under a recreational impact based on an ecomorphic approach. The article assesses the level of recreational transformation of the soil macrofauna of public green spaces in the city of Melitopol on the territory of Novooleksandrivskyi Park. For research purposes, a testing site was allocated in an area with a high level of recreational load, with samples taken within this site. To collect soil macrofauna and assess soil properties at each point of the testing site, soil and zoological tests were carried out and the following soil indicators were measured: temperature, electrical conductivity, humidity and soil penetration resistance, litter depth and grass stand height. The community ordination was performed using two approaches: OMI and RLQ analysis. The study found that the ecological niches of soil macrofauna in recreational conditions are spatially structured. The main factors for structuring the ecological niche of soil macrofauna within the study area are soil penetration resistance in the range of the entire measured layer, soil moisture, and distance to trees. As for the number of species, the basis of the coenomorphic structure of soil macrofauna are silvants (45.5%) and pratants (24.2%). As for the species abundance, the basis of the coenomorphic structure of macrofauna comprises pratants (64.5%), slightly less stepants (19.1%) and silvants (16.1%), and sporadic occurrence of paludants (0.2%). Such coenomorphic structure can be considered as ecologically labile. Zoophages, hemiaerophobes, and megatrophs are tolerant to a high level of recreational load. The area corresponding to the highest level of recreational load is vacant. This indicates factual absence of soil macrofauna species that could exist amid intense recreational exposure

Characterization of the soil compaction based on the mapping of the apparent electrical conductivity

Based on the measurement of soil penetration resistance (PR), it is possible to identify compacted soil layers, where root growth may be harmed, affecting crop development and yield. The objective of this work was to analyze the use of management zones (MZ), delimited on the basis of mapping of the spatial variability of the soil apparent electrical conductivity (ECa), in the differentiation of soil compaction levels. The work was carried out in a 25.8-ha no-tillage area, cultivated under a center pivot. The ECa was measured under two soil moisture conditions (13.7 and 16.45%), using the Terram® equipment. Soil penetration resistance (PR) was measured using the SoloStar PLG5500 penetrograph. Based on the spatial variability ECa mapping, management zones (2, 3, and 4 zones) were delimited. The mean PR values ??of each MZ were compared by the t-test of means. It was possible to differentiate mean values ??of penetration resistance (PR), which vary from 0.9 to 2.10 MPa, from the characterization of management classes generated on the basis of the ECa spatial variability. The highest stratification of PR values ??was obtained as a function of sampling directed at delimited management zones when the soil had lower moisture content (13.7%). The highest mean PR values ??were obtained for the split of the ECa map into at least three classes. It was identified that for the study area there is no need to perform any mechanical decompaction operation.

Physical properties of a soil under a pig slurry application and organic matter activators

To investigate the effects of organic matter activators combined with a pig slurry on a soil’s physical properties, a field experiment was carried out in a monoculture of corn (2015–2017). Three pig slurry application variants complemented with the activators in question, i.e. with PRP SOL spread directly on the soil surface (SOL), with Z’fix added to the slurry during the pig housing (ZF) and with a combination of both PRP SOL and Z’fix (ZF_SOL), were compared with just the pig slurry (C) under an equal dose of nitrogen and a uniform growing technology. According to the results, a positive effect of the penetration resistance with the pig slurry and the activators of organic matter (Z’fix and PRP SOL) was not proven. The saturated hydraulic conductivity was demonstrably better achieved with the Z’fix activator, but PRP SOL activator also provided a certain improvement. The largest change in the unit draught was observed in the ZF_SOL application (20% increase). The results seem ambiguous; however, they give a good indication of the activators’ effect in practice. Nevertheless, the findings would certainly benefit from further verification.

Knowledge Based Prediction of Standard Penetration Resistance of Soil Using Geotechnical Database

The current study aimed at predicting standard penetration resistance (N) of soil using particle sizes and Atterberg's limits. The geotechnical database was created subsequent to the field and laboratory testing. The sample collection points were distributed in a mesh grid pattern to have uniform sampling consistency. Artificial Neural Networks (ANN) were trained on the database to build a knowledge-based understanding of the interrelation of the given soil parameters. To check the efficacy of the model, the validation was carried out by predicting standard penetration resistance (N) for another 30 samples which were not included in the training data (444 samples). The trained ANN model has been found to predict N values in close agreement with the N values measured in the field. The novelty of the research work is the standard penetration prediction employing basic physical properties of soil. This proves the efficacy of the proposed model for the target civil engineering application. Doi: 10.28991/CEJ-SP2021-07-01 Full Text: PDF