Analysis of Surface Deformation and Physical and Mechanical Parameters of Soils on Selected Skid Trails in the Gorce National Park

Skidding is considered to be one of the most stressful works for the forest environment. This paper presented the results obtained from the analysis of soil deformation and selected physical and mechanical parameters of soils on skid trails in the Gorce National Park. The study analyzed two horse and tractor skid trails that are in continuous use in the park. Measurements of parameters were recorded before (summer) and after (autumn) a total of 81 skidding cycles, using a profilometer and a penetrometer, and soil samples were collected for analysis. The measurements obtained from the horse trails indicated that soil compactness was considerably higher in the lower sections of the trails and on the side more loaded by horse traffic and the transported load, which was related to the trail course in the field. The values of penetration resistance were high in the middle of those trails, reaching 6.8 MPa in the layer up to 10 cm. In the tractor trail the values of soil compactness reached 7.62 MPa in the layer up to 10 cm deep and were similar across the width of the trail and deep into the soil profile, with only slight changes observed in the monitored period. As a result of skidding, there were increases in the maximum depth of ruts reaching up to 4.6% on horse trails and up to 10.8% on tractor trails. Soil erosion per 10 m of trail caused by skidding and other natural factors during the study reached 1.314 and 0.390 m3 for the tractor and horse trail, respectively, wherein volume of skidded wood on the tractor trail was 180.1, and 18.1 m3 on horse trails. This confirms that the volume of eroded soil on the trails is determined by the type of skidder used and volume of skidded wood, so it is important to choose the right kind of skidder based on the conditions in which the skidding work will be carried out.

Experimental research of equipment for burying in the ground the drip irrigation lines

The equipment for burying in the ground the drip irrigation lines was designed and built at INMA Bucharest, within a complex research project carried out in partnership with other institutes, universities and research stations in Romania. The equipment is intended for drip irrigation technology for field crops. Subsurface crop irrigation technology is a variant of the classic drip irrigation technology, in which the drip lines are buried below the soil surface, providing water directly to the root zone of the plants. The depth of burial and the distance between the drip lines depends on the type of soil and the structure of the roots of the crop. The activities prior to the experimental research consisted in determining the characteristics of the test field (soil compactness, soil moisture, geographical coordinates of location). Experimental research of the equipment aimed at determining the energy indices (working speed, traction force, traction power, working capacity and fuel consumption).

Experiment Study of the Failure Mechanism and Evolution Characteristics of Water–Sand Inrush Geo-Hazards

Water–sand inrush disasters are frequently encountered during underground engineering construction in karst terrain. The objective of this paper is to study the failure mechanism and evolution characteristics of water–sand inrush caused by the instability of filling medium in karst cavity, as well as the impacts of soil compactness, hydraulic pressure and confining pressure on the instability process. In response to this purpose, a stress-controlled seepage test apparatus in consideration of particle loss was designed, and a series of seepage tests were performed correspondingly. The test results indicate that: (1) Based on the nonlinear feature analysis of water-outflow pattern, the water–sand inrush process can be divided into the “slow flow” stage, “transition flow” stage and “pipe flow” stage by Transition Point I, II. (2) The decreasing soil compactness and increasing hydraulic pressure both exponentially facilitate the seepage-erosion process by increasing the particle-erosion ability; the increasing confining pressure extends the “slow flow” stage and shortens the duration of the “transition flow” stage, ultimately advancing the occurrence of the “pipe flow” stage; the existence of critical hydraulic pressure for the seepage-erosion progress is confirmed, the occurrence of the “pipe flow” stage is significantly advanced once the hydraulic pressure over the critical value. (3) The particle loss caused by the seepage-erosion process is the internal mechanism of water–sand inrush, the variation characteristics of water-outflow pattern are crucial external manifestations correspondingly. Therefore, with the monitoring of water-outflow pattern variation tendency as indicators, the critical status of water–sand inrush can be near-real-time identified, which offers experimental foundation for the early warning and forecast of the occurrence of water–sand inrush.

Effect of subsoiling depth on soil physical properties and summer maize (Zea mays L.) yield

The present study was carried out in 2016–2017 to assess the effect of subsoiling depth on the soil bulk density, stability of soil structure, soil physical properties and summer maize yield based on a field experiment started in 2015. Four tillage depths were studied: conventional tillage 25 cm (CT₂₅); subsoiling tillage 30 cm (ST₃₀); subsoiling tillage 35 cm (ST₃₅) and subsoiling tillage 40 cm (ST₄₀). The results showed that at the 20–50 cm depth ST₃₀, ST₃₅and ST₄₀ decreased the mean soil bulk by 4.59, 7.13 and 8.27%, respectively, and at the 0–40 cm depth reduced soil compactness by 17.62, 23.63 and 36.42%, respectively, as compared to CT₂₅. ST₄₀ reduced soil compactness in the 0–40 cm soil layer under conditions of relative drought (during the maize season growing season of 2016), ST₃₅ and ST₄₀ increased macroaggregates (> 0.25 mm), improved the stability of the aggregate structure (geometric mean diameter and mean weight diameter) (20–40 cm), increased soil water storage capacity at 40–60 cm and increased maize yield by 7.89% and 8.91%, respectively. Considering the improvement of soil properties and crop yield, ST₃₅ was the optimum method to increase maize yield and modulate soil physical properties in the North China Plain.

The Effect of Timber Harvesting on Fluctuation of Peat Water Level and Subsidence of Peat-Soil Surface

<p>A goal of timber harvesting is to increase timber production through removing the timber from the forest using some harvesting techniques. A peatland is a fragile ecosystem and may degraded easily. Logging activities may adversely affect the soil compactness that disrupt the peat drainage system as well as cause subsidence, then ultimately may cause the sustainability of peat. This study was focused on examining the effect of timber harvesting acivities in peat forest plantation. The peatland damage may in the form of increased bulk density, water level fluctuations of peat (TMA), subsidence, irreversible and carbon emissions. The objective of the study is to find out the effect of timber harvesting in peatland plantations to peat water fluctuations and subsidence. The results showed that logging activites caused : (1) The average of water table and water level are about 1.03 and 0.967 m; and (2) Subsidence about -8 to -12.5 cm with the average is -11.0 cm. </p>