Soil properties affected by passing the machines in skid trails and establishment of natural regeneration and herbaceous palnts in these routes after the harvesting operation could be a suitable opportunity to study the reaction of different plant species to soil conditions. This study has been done in district 1 of Nav forest, Guilan/Iran. The skid trails where have been abandoned without traffic for 10 years were chosen among the available skid trail routes. Soil samples were taken and type and the number of natural regeneration in skid trials and adjacent forests (natural forests) wre recorded. The results showed that among soil physical properties, soil bulk density, porosity, saturation moisture percentage and soil texture differed significantly between skid trail routes and natural forest. The natural regeneration of cappadocia maple, hornbeam and alder showed significant difference between natural forest and skid trails routs, while natural regeneration of beech and Velvet maple did not show any significant differences. The regeneration of alder was significantly higher in skid trail routes compared to natural forests, but for hornbeam and maple this regeneration was better in natural forest. Among soil physical properties, bulk density, porosity and soil texture showed significant correlation with amount of natural regeneration and among tree species, cappadocia maple showed the higher correlation with soil physical properties. This study showed that the natural regeneration of some species is affected by soil physical properties. In addition to the determination of natural regeneration responses to soil physical properties, the results of this study could be used in silviculture and forest management.

A field experiment was conducted to investigate the effects of sewage sludge and of time lapse after sludge application on soil physical properties. Four sewage sludge treatments (0, 25, 50, and 100 ton/ha) in a complete randomized block design with three replications were applied and mixed to a depth of 20 cm. Wheat was planted and soil physical properties were measured 23, 85, 148, and 221 days after sewage sludge application. Sewage sludge application significantly increased MWD, hydraulic conductivity, final infiltration rate, moisture percentage at 1/3 and 15 bars, and plant available soil moisture, while it significantly decreased soil bulk density. In general, the best results obtained with the 100 ton/ha sewage sludge treatment. Time lapse after sewage sludge application caused soil physical properties to approach the values of the control. However, even 221 days after sludge application, the 50 and 100 ton/ha treatments had significantly different values compared with the control treatment. The results in this research show that sewage sludge can help to improve soil physical conditions and this effect persists over long periods. This effect is specially important with plant available soil moisture and infiltration.

Accurate، rapid، and low-cost instruments for in situ measurement of soil physical properties can simplify generation of their maps in different scales for site specific management of soil and water resources in these areas. One of these instruments is electromagnetic induction device (EM38) that has shown many capabilities in determination of some soil physical properties، both at the surface and in depth. Main objective of this study was to investigate EM38 capabilities in determination of some soil physical properties such as weighted and volumetric water contents (12θm «> and 12 θv)»>، clay، silt، and sand percentages، temperature، apparent bulk density (12ρb«>)، and porosity (n) in saline pistachio orchards of Ardakan، Yazd province. For this purpose، 90 EM38 reading points and 25 soil sampling points were selected in the region. Disturbed and un-disturbed soil samples were collected from four discrete depths (0-30، 30-60، 60-90، and 90-120 cm) and the mentioned parameters were determined. Afterwards، relationships between EM readings and different soil properties were calculated through simple and multiple regression methods. Results of this study showed no significant correlations between EM38 readings and clay، sand، silt contents and temperature، while significant correlations were found between horizontal EM38 readings (EMh) and 12 ρb»> with R2 of 0. 68 and 0. 65 for 0-30cm and 0-60cm soil depths، respectively. Additionally، relationships between EM38 and 12θv «>of 0-30cm، 0-60cm، and 0-90cm soil depths were significant with R2adj of 0. 69، 0. 74 and 0. 78، respectively. Based on these relationships، maps of 12ρb،» > 12θv«> and porosity (n) of different soil depths were prepared and interpreted. Results of this study، however، show suitability of EM38 instrument for low-cost and rapid mapping of some soil physical properties such as moisture، bulk density، and porosity.

Protective measures are needed to reduce the negative impacts of soil compaction. Water diversions are one of the management tools to reduce the negative impacts of ground skidding and helping soil recovery. In this research, the effects of constructed water bar were studied on the process of soil physical properties recovery in skid trail in west of Guilan. Seven years after logging completion and conservation of skid trail by constructed water bar, changes in soil physical properties were evaluated in two slope classes and three traffic classes in 40 m2 sample plots at wheel tracks and between them. Control samples were selected within 30 m from the edge of the skid trail. Soil samples were collected using a cylinder to a depth of 10 cm. Soil penetration resistance and rut depth were measured by analog hand-held soil penetrometer and rut 5 meter leveling rod, respectively. Influence of slope and traffic changes on soil physical properties was investigated in two treatments, three replications, and 72 samples. The results showed that the slope of the skid trail, traffic intensity and their interaction have significant effective on bulk density, total porosity, penetration resistance and rut depth. Mean bulk density, total porosity and penetration resistance in slope below 10% and low traffic treatment were not significantly different from control area. Overall, the results of study indicated that after log skidding, water bar construction had positive effects on soil physical properties of low slope and traffic trails.

To find the best treatment of cow manure mixing using the best tillage methods and improving sugarbeet yield and soil bulk density and chemical properties, a randomized complete block design the form of a strip plot was replicated three times. Three rates of manure (0, 20, and 40 t/ha) and five tillage methods were used. The analysis of two years of combined data showed that cyclotiller with the mean of 61093 kg/ha and sweep had the highest yield and effect on soil bulk density. Soil chemical properties like soil organic carbon, soil phosphorus, and soil potassium were also measured for data analysis. The results of two-years analyses of data also showed that the cow manure treatments caused more yield of sugarbeet and improved soil physical properties like reducing soil bulk density and soil compaction. Also, using secondary soil tillage machines of cyclotiller and sweep can improve the mixing of manure with soil and soil physical properties and yield of sugarbeet and sugar percentage. In other words, using a cyclotiller and sweep raised the yield and sugar percentage of sugarbeet and reduced soil compaction.

The present study was done to investigate a few decades application of raw municipal wastewater on soil physical quality and biological yield of wheat in Harsin. In this way, the main soil physical properties, which effect on soil physical quality, and total concentrations of some heavy metals in the soils of ten sites, that have been irrigated by wells water or wastewater, were statically analysed. The results showed that the use of wastewater, while added organic matter to the soil, improved aggregate stability, reduced soil bulk density, and increased other soil physical properties, including: saturated hydraulic conductivity, total porosity and saturation percentage. The total concentrations of Zn and Fe in the lands that had been irrigated by wastewater were significantly more than in the lands had been irrigated by wells water, while, concentrations of Cr, Pb and Ni were not significantly different. In general, application of wastewater improved the soil physical quality and meanwhile increased biological yield of wheat in the study area.

Reasonable estimation of soil physical properties is very important for optimal management of soil and water resources. Estimation of soil physical properties is usually time consuming and expensive. Geostatistical methods can be used as suitable tools to estimate such properties. In order to analyze spatial variability of soil properties in Dareh Viseh rangelands, a number of 78 soil samples from 0-30cm soil depth were taken and transferred to laboratory. Some soil properties including clay, silt, sand and bulk density were measured in laboratory. After normalizing the data, the semivariograms were obtained and evaluated. The Kriging, inverse distant weighting and radial basis function methods were then evaluated for the obtained data. To compare these methods, the cross validation method was used by statistical parameters of Mean Absolute Error (MAE) and Mean Bias Error (MBE). The results showed that the Kriging method can provide more reseanable predictions for silt, sand and bulk density, while the radial basis function provides better estimate to predict clay content in the study area.

The main purpose of this study was to assessment the effects of long-term irrigation with pollutant water on soil physical properties of two water treatment as pollution water and well water during two years (2013 & 2014) on Gharesoo River located in Doroodfaraman district, in 20 km south of Kermanshah. This study was performed in three soil layers 30, 60 & 90 cm with three replications in randomized complete block design. In this study, soil physical properties including saturation hydraulic conductivity (Ks), soil moisture characteristic curve and parameters (θFC, θPWP & AW), bulk and practical density (ρb & ρa) and porosity (η) were determined. The results of statistical analysis showed that there was no uniform trend between various parameters. Using of the pollutant water was caused a significant difference at 5% level on saturated hydraulic conductivity but on the other physical properties of soil no significant difference were found. The results showed that irrigation with pollution water in loam soil increased saturation hydraulic conductivity ratio significantly but it decreased the moisture in FC, PWP and also bulk and practical density. It can be concluded that the use of pollutant water increased the soil porosity.

Soil quality can be considered as a comprehensive index for sustainable land management assessment. Studying the most important soil physical properties and combining them as an index of soil physical quality (SPQI) could be used as an appropriate criteria for evaluating and monitoring soil physical changes. In this regard, this study was conducted to determine the most important soil physical properties and calculate the SPQI of medium to coarse-textured soils of Khorasan-Razavi province.
Torogh Agricultural and Natural Resources Research and Education Station of Khorasan-Razavi province is located in south-east of Mashhad city (59° 37' 33"-59° 39' 10" E, 36° 12' 31"-36° 13' 56" N). Soil texture variability in this research station is one of its outstanding features. The soil textures are classified into loam, silt loam, silty clay loam, clay loam, and sandy loam. More than 90% of agricultural soils in Khorasan-Razavi province are classified in these five texture classes. Using the available data, 30 points with different soil textures and OC contents were selected. The soil samples were collected from 0-30 cm soil depth at each point. Intact soil cores (5 cm diameter by 5.3 cm length) were used for sandbox measurements, and disturbed soil samples were used to determine other properties. Required laboratory analysis and field measurements were conducted using standard methods. In this research, 35 soil physical properties as total data set (TDS) including: soil moisture release curve (SMRC) parameters, particle size distribution and five size classes of sand particles, soil bulk and particle density, dry aggregates mean weight diameter (MWD) and stability index (SI), S-index, soil porosity and air capacity, location and shape parameters of soil pore size distribution (SPSD) curves, relative field capacity (RFC), plant available water measured in matric pressure heads of 100 and 330 hPa for the field capacity (PAW100 and PAW330), least limiting water range measured in matric pressure heads of 100 and 330 hPa for the field capacity (LLWR100 and LLWR330), integral water capacity (IWC) and integral energy (EI) of different soil water ranges were measured and calculated for 30 soil samples. The most important soil physical properties were selected using principal component analysis (PCA) method by JMP (9.02) software. Selected physical properties as minimum data set (MDS) were weighted and scored using PCA results and scoring functions, respectively. In this study, three types of linear scoring functions were used. The soil physical quality index (SPQI) was calculated by two scoring and two weighting methods for each soil sample and the differences between these four SPQIs were tested by sensitivity index.
Principal component analysis results showed that among 35 soil physical properties (TDS) which were studied at this research, six properties of mean pore diameter (dmean), PAW100, total porosity (PORT), EI LLWR330, SI and PAW330 accounted for about 90% of the variance between soil samples. Weight of the selected properties (MDS) was calculated by the ratio of variation in the data set explained by the PC that contributed the selected property to the total percentage of variation explained by all PCs with eigenvalue ˃ 1. In this research, the parameters of PAW100, total porosity (PORT), SI and PAW330 were scored using scoring function of more is better, EI LLWR330 was scored using scoring function of less is better and dmean was scored using scoring function of optimum by two scoring methods with score ranges of 0.1-1 and 0-1. Considering unweighted and weighted MDS and two ranges of scores, four SPQIs were calculated for each soil sample. The results showed that SPQIs which were calculated by the MDS derived from PCA method and scoring weighted MDS at the range of 0-1, had the highest sensitivity index and could represent the differences between the studied soil samples better than other SPQIs. By this method, maximum and minimum SPQI values for the studied soils were 0.82 and 0.12, respectively. SPQI is a relative comparison criterion to quantify the soil physical quality which could be applied only for the studied soils with specific characteristics.
The results of this research showed that minimum data set (MDS) explained about 90% of the variance between soil samples. Combining MDS into a numerical value called soil physical quality index (SPQI) could be used as a physical comparison criterion for the studied soils. From the SPQI based on the MDS indicator method, soil quality was evaluated quantitatively. Soil samples with grade I, II, III, and IV accounted for 10%, 36.7%, 30%, and 23.3% of the soil samples, respectively.

Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions.