Time domain reflectometry (TDR) is a widely used method for measuring the dielectric constant (Ka) and bulk electrical conductivity (σa) in soils. The TDR- measured σa and Ka can be used to calculate the soil solution electrical conductivity, (σp). A theoretical model describing a linear relationship between bulk electrical conductivity, σa, and dielectric constant, Ka, in moist soil was already presented. By using this linear relationship, the pore water electrical conductivity, σp, can be estimated in a wide range of soil types without soil- specific calibration. The objective of this study was to evaluate the linear model presented previously for TDR. The previous study was on light texture soils but in this study we used clay, clay loam, loam, silty clay and silty clay loam textures. The results showed that the linear model performed well for light texture soils but not for heavy textures. Such poor result for heavy texture is mainly due to this fact that dielectric constant pore water was lower than 80 which was proposed as default by model. This study showed that for heavy texture soils dielectric constant of pore water is smaller than light textured soils.

Wenner direct contact method is a method of estimating apparent electrical conductivity (ECa) of agricultural soils in situ. This method can be affected by factors such as quality of electrodes in contact with soil, type of employed electric current, moisture content, clay content and compaction of soil. In this research, the effect of electrode type (rod and plate) and electric current type (direct and alternating) on accuracy of estimating soil ECa has been investigated to design a soil EC mapper. A prototype soil EC meter based on direct contact method has been made. The device assessed by a completely randomized experimental design with factorial layout. The independent variables were soil salinity (five levels), electrodes type (two levels) and current type (two levels).Four soil types with different clay contents from regions around Mashhad city (Khorasan Razavi, Iran) have been used with three replications. The results analyzed with SPSS17 software and validated with 1:1 soils water extract EC’s. Significant difference between electrodes types and electric current types was observed. The correlation coefficients of direct contact measured EC’s with soil water extract EC’s was between 0.94 and 0.99 for all treatments. Based on the results of this research, plate type electrodes and AC current were recommended for the design of tractor rear mounted soil EC mapper.

The issue of soil salinity is one of the snags for increasing agricultural productivity, which must be inhibited by appropriate devise and scientific management. One way to identify salty areas of farm lands is to prepare salinity maps. In this study, a prototype soil apparent electrical conductivity measuring and mapping device, was designed and built. This device employs direct contact method of electrodes with soil (Also called Wenner method). The system inputs include power supply voltage, location signal from a GPS receiver and signal of voltage between the electrodes. The outputs include the apparent electrical conductivity with respective to geographical coordinate that created in a TEXT file, and then transmitted through a RS-232 serial port to a PC.Electrical conductivity data calibrated and mapped using ESAP-95 software package. To evaluate the device, electrical conductivity map of a land with area of 0.8 Ha surveyed in two ways: using the on the go EC mapper and capturing soil samples manually. The results of these two methods were then compared. Assessment of the device in a clay-loamy soil with low salt level, showed a good correlation with the laboratory EC, having mean error (ME) of -15.27mS.cm-1. Point to point comparison between surveyed data and laboratory EC’s shown that in 67 percent of measurements the errors were under 10 percent. These errors are acceptable mainly due to unknown soil variables and in comparison with other research findings.

Soil salinity is an important environmental issue that reduces soil productivity. For optimal management of soil resources, quantitative monitoring of soil salinity, temporal changes and spatial analysis of the factors affecting it are necessary. The purpose of this study is to extract the soil salinity distribution map and its spatial analysis after more than normal rainfall in the rainy year of 1997-98 in western Iran. Using Landsat satellite imagery and GDVI index and algorithm written in Google Engine system, soil electrical conductivity map was extracted and classified into five salinity classes. The results showed that in general, soil salinity has decreased in the study area. Areas with high salinity that are in the low altitude class have not changed. If the precipitation factor in this study period is the most important factor in changes in salinity distribution, this factor could not have a great effect on the salinity class, but the medium salinity class had the most changes. Move the soil surface of this class down. For the ellipse, three times the standard spatial deviation of the northwest to the southeast was obtained, which shows that more than 99% of the salinity dispersion follows the spatial arrangement of altitudes, precipitation and dispersion of soil categories in this direction. Statistics of 0. 4566 of Moran index and P_Value showed 0. 00 spatial salinity of soil salinity in the west of the country.

Electrical conductivity and acidity of soil are the most important chemical factors of soil for agriculture. The nature of soil is in such a way that its change has a continuous form. The method that can take into account this continuity will be able to show a better picture of change in soil characteristics. Objectives of this research are to investigate the relations between measured electrical conductivity and soil acidity of Qom plain, and clustering, compare the clustering methods, determine the optimum numbers of cluster, and to zone the clusters in the study area. Accordingly, two fuzzy clustering methods FCM and GK, were used for data mining and clustering of 465 measured data. For estimating the appropriateness and comparison of two methods, some criteria including Partition Coefficient, Classification Entropy, Partition Index, Separation Index and Xie and Beni's Index were used. Data mining results showed that the optimum number of clusters for FCM and GK method was 15 and 17, respectively. After investigating the results of clustering and based on the criteria of appropriateness, it was indicated that GK was the best clustering method. According to this method, 295 data from 465 measured samples had more than 40 percent of membership function. So, 9 clusters from 17 clusters had more than 20 members. Then salinity-alkalinity zoning based on GK method to show the clusters distribution better in the study area was prepared. This prepared fuzzy map explained that most of Northwest and west belonged to cluster 1 and eastern parts of study area include belonged to cluster 17. Based on this, salinity-alkalinity and the ensuing soil degradation in east of study area is more likely than the west of it.

An empirical electrical conductivity assessment of nanofluids comprising CuO nanoparticles water-based in different concentrations, particles size and various temperatures of nanofluids has been carried out in this paper. These experimentations have been done in deionized water with nanoparticles sizes such as 89, 95, 100 and 112 nm and concentrations of 0.12 g/l, 0.14 g/l, 0.16 g/l and 0.18 g/l so nanofluids obtain in temperatures such as 25oC, 35oC, 45oC and 50oC for investigation of their electrical conductivity. It is observed that, in water-based nanofluids, the electrical conductivity increases with increasing in both nanofluids temperatures and concentration respectively in the range 25-50oC and 0.12-0.18g/l. But in nanoparticles size rising in nanofluids we observe that electrical conductivity has a few increase when nanoparticles have 95nm diameters, so decrease for biggest nanoparticles such as 100 and 112nm. It seems that there is an optimum in electrical conductivity with resize of nanoparticles.

Introduction: One of the main factors affecting plant growth is soil compaction. More attention should be paid to soil compaction than the past. Soil compaction not only destroys the soil structure, but also leads to a heavier soil structure with natural cavities. The rolling resistance reduces energy and occurs when the tire moves on a soft soil and rolling resistance of the tire is brought about by two processes of soil deformation and wheel change. This force is influenced by the design of the tire, the parameters of the tire, and the characteristics of the soil. The apparent electrical conductivity (ECa) indicates the direct conductivity of direct current in the soil. The electrical conductivity is effective on chemical and physical properties, including the amount of soluble salts in the soil, salinity, cation exchange capacity, soil texture, organic matter content, moisture content and water holding capacity, and compression. The purpose of this study was to investigate the effect of soil compaction and soil moisture on the soil electrical conductivity and rolling resistance of the Messy Ferguson 285 tractor rear tire. This study showed the density and soil moisture were associated with soil electrical conductivity and rolling resistance. Materials and Methods: This test had independent and dependent variables. The dependent variables including rolling resistance and electrical conductivity, whose values were measured by a torque meter and a portable EC meter. Independent variable comprised of soil compaction and soil moisture measured by Penetrologger and soil moisture measurement tools including soil harvesting cylinder, scale and oven device. Experiments were carried out in the soil bin Laboratory with a 1. 7 m wide, 24 m long and 1 m deep with soil texture of clay loamy in Agricultural Engineering Research Institute (Karaj). The soil was prepared layer by layer and up to a depth of 20 cm by the soil preparation unit. In all experiments, the vertical load was fixed at 4000 N and the tire pressure of 6899 N. m-2. On each layer, the water was evenly sprayed to reach the desired moisture. To do this research, factorial experiment with soil compaction levels at 3 levels of 2, 4 and 6 roller passes, respectively, with the bulk density of 1. 47, 1. 54 and 1. 69 g. cm-3 and soil moisture at 3 levels of 10%, 12% and 14% were used in 3 replications. Data were analyzed using SPSS software. The tools used included the tire test rig, the rear tire of a Massy Ferguson 285 tractor, the soil preparation unit, and the measuring instrument, including the torque meter, the penetrologger and the portable EC meter. Results and Discussion: In this experiment, it was found that as the amount of moisture increased, the compaction was also increased. The test indicated that the soil rolling resistance was increased by decreasing the soil moisture content. Moreover, increasing in the soil compaction ration led to decreasing the soil rolling resistance. The CI was used at a depth of 20 cm to 0 cm. In these experiments, we concluded that the higher density of compaction resulted in increasing the soil cone index (CI). This index was directly related to the compaction, but it had an adverse relation with the moisture. It means the lower amount of moisture led to the higher amount of CI. The amount of electrical conductivity of soil was measured at a depth of 0-25 cm. In this experiment, we concluded that the higher compaction ratio resulted in the higher electrical conductivity. It means that electrical conductivity had a direct relation with the compaction and the moisture content. The lower moisture content led to the lower electrical conductivity of the soil. Conclusions: In general, considering all the tests and comparison between rolling resistance, soil cone index and apparent electrical conductivity before and after roller passing, it can be concluded that as the amount of moisture content increased, the soil cone index (CI) decreased. The soil cone index (CI) had a relationship with the moisture. The lower moisture content led to the lower soil moisture resistance, as well as the higher moisture content resulted in the higher soil resistance. The lower amount of soil compaction showed the greater soil rolling resistance, and the greater amount of soil compaction caused to the less soil moisture resistance. The electrical conductivity before and after the roller pass was different in the case of roller pass, and the higher amount of moisture led to the greater electrical conductivity, because the electrical conductivity was directly related to the moisture and the compaction affects all parameters.

One of the most important issues in agricultural machinery section is tyre-soil interactions. In this study, a single wheel tester was used to follow experiments in controlled conditions in a soil bin. A Goodyear 12. 4-28, 6 ply tractor drive tyre was operated at three vertical loads of 6, 9 and 12 kN, three inflation pressures of 80, 120 and 160 kPa and three moisture content of soil: 11. 20, 14. 86 and 18. 68 % d. b to investigate the effect of the variables on these parameters: contact area, contact pressure, compaction, and soil apparent electrical conductivity. It was found that medium contact pressure had a direct relation with vertical load, inflation pressure and moisture content. A regression model with R-square of 0. 946 was achieved to predict contact pressure. Soil electrical conductivity changes was predicted with acceptable determination coefficient of 0. 850 by using of vertical load, inflation pressure and moisture content. Determination coefficient magnitude for models to predict resistance to soil penetration (cone index) using soil apparent electrical conductivity, decreased when moisture content was increased. The vertical load and inflation pressure were found two factors controlling the soil apparent electrical conductivity changes in low and high moisture content, respectively. Error percentage in using soil apparent electrical conductivity parameter to estimate the penetration resistance increased with increasing moisture content.

Soil salinity and alkalinity are considered as the most important problems in arid and semi arid areas. This study has been done to investigate the spatial variability of salinity and sodium adsorption ratio which have reciprocal effects on pistachio growth in the Kosarrize region in Rafsanjan. For this purpose a regular network of 500 meter intervals was considered and 192 soil samples were from 0-30 and collected 30-60 cm depths. Electrical conductivity of saturated soil extract (EC) and sodium adsorption ratio (SAR) were measured using standard methods. Statistical results showed that based on Pearson test, high positive correlation exists between EC and SAR at 99% confidence level. Therefore most of the salts must be of na type. Kriging maps illustrate that the variability of both parameters are greater in the first depth than the second one which is the result of different management strategies in the area. Also maps showed that Existences of excess salinity, SAR and also immethodical groundwater withdrawl and successive droughts in recent years have been considered as the main reasons of weak yield and even the loss of a major part of pistachio orchards in the region. The results showed that soil salinity and sodium in non planting areas are severe which illustrates the impact of mismanagement of the increased EC and SAR in the pistachio regions.

Infiltration and coefficients of infiltration equation are of the most important parameters in the design and evaluation of irrigation systems. The objective of this research was to compare the cumulative infiltration, infiltration rate and electrical conductivity of different soil textures including: sandy loam, silt and clay under saline water 0.58 dS/m, 5 dS/m and 10 dS/m with magnetized and non-magnetized water. Magnetized water was obtained by passing the water through a strong permanent magnet installed in a feed pipeline. Infiltration coefficients of different soils obtained based on Kostiakov-Lewis equation. The results showed that, magnetized water caused increasing of cumulative infiltration and also increasing of infiltration rate in different soil textures and all saline water treatments and this effect was significant (p<0.01). At the end season, in non-magnetized water and saline water of 5 dS/m and 10 dS/m, the average cumulative infiltration was reduced 10.8% and 25.6% respectively as compared to control treatment. But, in magnetized water and saline water of 5 dS/m and 10 dS/m, the average cumulative infiltration was reduced 6.4% and 13.95% respectively as compared to control treatment.In addition, using of magnetized water caused to decrease the electrical conductivity in different soil depths (p<0.01). Magnetized irrigation water had most effect on the infiltration capacity and electrical conductivity of clay and sandy loam soil, respectively. With increasing of infiltration using magnetized water, evaporation was decreased and therefore, irrigation efficiency is increased.