Conductivity Values Of Soils Research Articles

Disentangling carcass size and climate effects on soil biogeochemistry during decomposition

When an animal dies the decomposition of its carcass releases multiple compounds that become available to soil microbiota altering soil biogeochemistry. This zone of affected substrate is characterized by significant changes to numerous soil biogeochemical parameters including pH, conductivity, microbial respiration rates, dissolved organic carbon (DOC), C/N ratios, carbon and nitrogen stable isotopes (δ13C and δ15N), and major/trace elemental concentrations. Although the effects of animal decomposition on these parameters have been recorded for various organisms and in a variety of ecosystems several knowledge gaps remain, including: the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). Here, we investigate how soil biogeochemical parameters are affected by the decomposition of a horse carcass (~660 kg) in a prairie ecosystem in comparison to beavers (~18 kg) in a temperate forest. Three parameters were identified as significantly influenced by carcass size: conductivity, DOC, and microbial respiration rate. Average soil conductivity underneath the horse carcass was three to fifteen times higher than control soils and reached a maximum at 1114 ADD, while maximum soil conductivity values were observed after 160 ADD in beaver-associated soils. Maximum DOC concentrations were observed after 160 ADD in beaver-associated soil (67 ± 40 mg C gdw-1) and after 1114 ADD in horse-associated soil (326 ± 115 mg C gdw-1). Microbial respirations rates were both greater in horse-associated soil and longer-lasting compared to beaver-associated soil. Respiration rates were greatest in two of the three horse-associated soils after 1114 ADD (~733 µg CO2-C gdw-1 day-1), which significantly differs compared to beaver-associated soils (300 ± 90 µg CO2-C gdw-1 day-1 at 160 ADD). Taken together, these results demonstrate that larger carcasses result in a greater release of decomposition products, including C, and greater stimulation of soil heterotrophic communities. Other measured biogeochemical indicators of decay suggest a mixed influence due to carcass size and climate, notably δ15N values of the soil, and major element concentrations. Climate was revealed to be more important in controlling changes to pH and gravimetric moisture than carcass size, with baseline soil conditions and type playing critical roles. Additionally, in semi-arid regions such as western South Dakota, the role of wet-dry cycles on carcasses undergoing decomposition may help to explain the pulses observed with C concentrations and C cycling. This study provides the first direct comparison of soil biogeochemistry associated with the decomposition of two different sized taxa decayed in two different climates. Attempting to normalize climate data using ADD was found to be an imperfect system that does not account for all climate variables affecting decomposition. Unravelling patterns in decomposition can better help to constrain nutrient cycling in modern and ancient ecosystems.

LEMP and ground conductivity impact on the direct lightning performance of a medium-voltage line

• Assessment of the LEMP influence on direct lightning overvoltages of medium-voltage distribution lines of the type equipped with a shield wire and surge arresters. • Comparison between the results obtained by a 3D-FDTD method and the LIOV-EMTP code. • The LEMP contribution on the overvoltages across insulators increases with increasing values of the soil conductivity. • The appropriate modeling of the LEMP effects is important for the lightning performance assessment of the type of lines considered in this paper. In medium-voltage distribution lines equipped with a multi-grounded shield wire and with surge arresters installed along the line at relatively short intervals, lightning outages associated with indirect lightning are less frequent than those associated with direct ones. The protection for this type of distribution lines is therefore dependent on the response to direct strikes. This paper presents and analyses the response to direct lightning overvoltages of lines of such a type located over a lossy soil considering the influence of the lightning electromagnetic pulse (LEMP), which is typically disregarded in the calculation of overvoltages due to direct strikes. The calculation results, performed by means of a three-dimensional finite-difference time domain (3D-FDTD) method and of the LIOV-EMTP code, indicate that the voltage across the insulator is enhanced by LEMP effects. In addition, it is shown that the enhancement due to the LEMP increases with the increase of the soil conductivity value. The modeling of the LEMP effects is therefore important for the accurate assessment of the lightning performance of medium-voltage distribution lines of the type considered in this paper, even when direct strikes are considered.

Stabilize Kent Çamuru ve Jips Uygulanmış Tuzlu Sodyumlu Topraklarda Arıtılmış Atıksuyun Islanma-Kuruma Döngülerinin Hidrolik İletkenliğe Etkisi

This study was carried out to determine changes in hydraulic conductivity of a saline sodic soil subjected to different wetting-drying cycles and treated wastewater after stabilized sludge sewage and gypsum application. In a factorial experimental design, the study was conducted with three replication by using 3 treatment sewage sludge doses (50, 100 and 150 t ha-1), 3 wetting-drying cycles (0, 7 and 14 days) and 2 different water types (fresh water and treated wastewater). The hydraulic conductivity values of the saturated saline-sodic soils were measured at 2, 12 and 24 hour intervals by using a constant level ICW laboratory permemeter. The increase in the applied treatment sludge dose significantly affected the hydraulic conductivity value of the soils and significantly depending on the measurement range. It was determined that irrigation waters have different properties caused a significant change in the hydraulic conductivity value of the soils, with measurements made at intervals of 2 and 24 hours. Depending on the measurement interval, it was determined that the increase in sewage sludge doses caused significant effect and very important on the soil hydraulic conductivity. The study results indicated that the application of gypsum and stabilized waste sludge to the soil cause an increase in hydraulic conductivity values. The study results indicated that the application of gypsum and sewage sludge to the soil cause an increase in hydraulic conductivity values of saline sodic soils. The study results also showed that treated wastewater containing low amount of suspended solids can be used safely for irrigation on the land have saline-sodic soils. The study result also indicated that by applying solid and liquid wastes obtained from treatment units to the saline-sodic soils can be significant contribution in terms of waste management and environmental protection.

Model for water infiltration in vegetated soil with preferential flow oriented by plant roots

PurposeThere is strong experimental evidence that root systems substantially change the hydraulic properties of soil. However, the mechanisms by which they do this remain largely unknown. In this work, we made the hypothesis that a preferential flow of soil moisture occurs in directions which follow the orientation and distribution of roots within the soil, and that this phenomenon alters soil moisture flow patterns.MethodsWe modified Richards’ equation to incorporate root-oriented preferential flow of soil moisture. Using the finite element method and Bayesian optimisation, we developed a pipeline to calibrate our model with respect to a given root system.ResultsWhen applied to simulated root distributions, our model produced pore-water pressure profiles which agreed with those derived from experimental saturated hydraulic conductivity values of soils vegetated with willow and grass. Agreement improved for simulated root distributions where root segments were oriented in a more realistic way, suggesting that the hydraulic characteristics of vegetated soils are a consequence of root-oriented preferential flow.ConclusionBy incorporating root-oriented preferential flow, our model improves the ability to describe and analyse water infiltration through vegetated soil. This could help optimise irrigation, forecast flood events and plan landslide prevention strategies.

Variation in biosynthesis of an effective anticancer secondary metabolite, mahanine in Murraya koenigii, conditional on soil physicochemistry and weather suitability

Murraya koenigii (MK) leaf being a rich source of bioactive secondary metabolites has received inordinate attention in drug development research. Formation of secondary plant metabolite(s) in medicinal plants depends on several factors and in this study the cause of variation in bioavailability and content of a vital bioactive phytochemical, mahanine in the MK leaves from different geographical locations of varying soil properties and weather parameters was determined. Accordingly, MK leaves and soil samples around the plant base in quintuplicate from each site across five states of India at similar time point were collected. Mahanine content was determined and compared among samples from different regions. The quantitative analysis data comprised that MK-leaves of southern part of India contains highest amount of mahanine, which is 16.9 times higher than that of MK-leaves of north-eastern part of India (which measured as the lowest). The results suggested that pH, conductivity and bacterial populations of the soil samples were positively correlated with mahanine content in the MK-leaves. For examples, the average soil pH of the southern India sites was in basic range (8.8 ± 0.6); whereas that of the north-east India sites was in slightly acidic ranges (6.1 ± 0.5) and mean soil conductivity value for the north east India soils was 78.3 ± 16.3 µS/cm against mean value of 432.4 ± 204.5 µs/cm for south India soils. In conclusion, this study proclaims that higher level of bioactive phytochemical, mahanine in MK leaves depending upon geographical location, weather suitability and soil’s physiochemical and microbial parameters of its cultivation sites.

Hydraulic Conductivity Values of Soils in Different Soil Processing Conditions

This study was carried out to determine physical and hydraulic properties of soils under different land use conditions. For this purpose, 9 samples in total (3 samples from each of three different areas; dry farming (D), irrigated land (I) and pastureland (P)) were collected. Soil texture, pH, lime, organic matter, hydraulic conductivity, aggregate stability, bulk density, particle density and porosity were measured. Infiltration measurements were made at each sampling point in the field. However, while there was no difference between the hydraulic conductivity of the fields used for agricultural activities in dry and irrigated conditions, significant differences were determined between the pasture areas and the treated areas. Differences were determined between infiltration measurements of soils and land use status. Positive correlations between infiltration and organic matter, aggregate stability and hydraulic conductivity were obtained as well as negative correlation between bulk density and organic matter content. The lowest infiltration rate was obtained for pastureland soil and the highest infiltration rate for the irrigated land soil. Therefore, increasing the organic matter content of the local soils will make significant contributions to sustainable soil management.

Irrigation of paddy soil with industrial landfill leachate: impacts in rice productivity, plant nutrition, and chemical characteristics of soil

Treated industrial effluents have high levels of nutrients and dissolved organic matter. The irrigation of rice by flooding can increase nutrient uptake and grain yield. Therefore, this study evaluated the nutrient contents in the shoots and grain of the rice crop and also the chemical of the soil after irrigation of the crop with leachate of the treated industrial effluent. A greenhouse experiment was conducted using pots filled with 20 kg of soil in a randomized block design with three replications. The treatments consisted of control (irrigation with distilled water) and four concentrations of the leachate (25, 50, 75, and 100 %) for irrigation. At the end of the experiment, the nutrient contents in tissues of rice plants, sterility of spikelets, and grain mass were evaluated. Results showed that irrigation with the leachate at 25 % content increased the macro- and micronutrients’ concentrations in the shoot biomass and grain, except for potassium and iron. Irrigation with the industrial leachate decreased tillering and grain yield; however, it increased chlorophyll content, sterility of spikelets, and sodium intake at this leachate concentration. The potassium and sodium levels and the electrical conductivity values of soils irrigated with treated industrial leachate were increased. The use of the treated leachate from industrial effluents is an alternative that reuses the nutritional load, but the volume of leachate should be limited and monitored to prevent the sodicity in the soil and problemsdue to eutrophication.

Effect of Soil Conductivity on the Design of Cathodic Protection Systems Used in the Prevention of Pipeline Corrosion

One of the most influential factors affecting the rate of corrosion of a buried pipeline and the design of the cathodic protection systems is the conductivity of the soil. The present paper is designed to study the effect of this factor on the design of cathodic protection systems, i.e. the current required to achieve comprehensive protection. Several corrosive environments were studied within the laboratory. The classification of environment corrosivity approved by ASTM was the base of the categorization of these environments. These environments were simulated by adding certain amount of distilled water mixed with weighed amount of sodium chloride to the soil. Several runs were carried out, whereas the conductivity of the soil and the linear polarization curves for the cathode and the anode were obtained during each run. The boundary element method (BEM) was used to compute the total current required using linear polarization curves as the boundary conditions for calculations. The BEASY software based on BEM was used to compute the total current required. The relationship between the total current and the soil conductivity values were drawn. Two equations governing and controlling this relationship were derived.

Soil salinity determines the relative abundance of C3/C4 species in Argentinean grasslands

ABSTRACTAim The C4 and crassulacean acid metabolism (CAM) pathways are adaptations to compensate for high rates of photorespiration and water and carbon deficiency. This is the first attempt to compare the relative abundance of C3 vs. C4 + CAM species in temperate and subtropical grasslands across a latitudinal gradient in central Argentina. We predict that under the same rainfall regime, C4 + CAM plants will have larger soil coverage in highly saline soils than in neighbouring non‐saline ones.Location Data were taken from three phytogeographical provinces in the Santa Fe province of Argentina: Chaquenian, Pampean and Espinal.Methods The salinity of the soil was estimated through aqueous solution conductivity. The proportions of species belonging to C3/C4 + CAM photosynthetic pathways were compared among halophyte and non‐halophyte communities with a χ2 homogeneity test. The sum of cover percentages corresponding to the C3 and C4 + CAM photosynthetic pathways were calculated and compared using analysis of variance (ANOVA).Results The soil conductivity values were higher in the halophyte than in the non‐halophyte communities for the same phytogeographical area. The C4 + CAM plants had much higher soil coverage values in halophyte than in non‐halophyte communities in the Pampean and Espinal phytogeographical provinces. The differences were not statistically significant in the Chaquenian province.Main conclusions Soil drought provoked by soil salinity results in a much higher soil cover by C4 + CAM plants in regions with positive to neutral water balance (i.e. Pampean and Espinal). This differential abundance pattern in C4 + CAM functional group is not observed in areas where a pronounced water deficit exists per se (Chaquenian region), and therefore C4 + CAM plants predominate in all environments regardless of soil salinity. Our results suggest that one of the main environmental forces driving the upsurge of C4 species in Argentinean grasslands might have been the strong local soil salinity gradient.

Variably saturated flow described with the anisotropic Lattice Boltzmann methods

This paper addresses the numerical solution of highly nonlinear parabolic equations with Lattice Boltzmann techniques. They are first developed for generic advection and anisotropic dispersion equations (AADE). Collision configurations handle the anisotropic diffusion forms by using either anisotropic eigenvalue sets or anisotropic equilibrium functions. The coordinate transformation from the orthorhombic (rectangular) discretization grid to the cuboid computational grid is equivalent for the AADE to the anisotropic rescaling of the convection/diffusion terms. The collision components (eigenvalues and/or equilibrium functions) become discontinuous on the boundaries of the computational sub-domains which have different space scaling factors. We focus on the analysis of the boundary continuity conditions by using anisotropic LB techniques. The developed schemes are applied to Richards’ equation for variably saturated flow. The anisotropy of the Richard’s equation originates from distinct soil conductivity values in both the vertical and horizontal directions. The method should on the interface between the heterogeneous layers maintain the continuity of the normal component of the Darcy’s velocity (total flux). Also the method should accommodate steep jumps of the moisture content variable (conserved quantity) resulting from the continuity of the pressure variable, a given non-linear function of the moisture content. The coupling between heterogeneity and the anisotropy is examined by using the distinct space steps in neighboring layers and tested against uniform grid solutions. Different formulations of the Richard’s equation illustrate the construction of distinct diffusion forms and their integral transforms via specification of the equilibrium components. Integral transforms are used to overcome the difficulties coming from the rapid change of the main variables on sharp fronts. The numerical assessment of the stability criteria and the interface boundary conditions extend the analysis of the Lattice Boltzmann schemes to nonlinear problems with discontinuous coefficients.

Field evaluation of tolerance to salinity stress in Iranian hexaploid wheat landrace accessions

The responses of 400 Iranian tetraploid and hexaploid landrace wheat accessions to variation in soil salinity were investigated at a field site in the San Joaquin Valley of California, U.S.A. The salinity treatments were represented by soil conductivity values (EC e ,) of 1.0 (control), 5.0, and 8.0 dS m−1 and were maintained by irrigation with water of similar or slighly higher conductivity. A subset of 200 hexaploid accessions was analyzed from the first year of study. For the second year, 77 accessions were selected as having high, low, or random salinity tolerance based on the Fischer-Mauer stress index (S) estimated in the first year. In both years the accessions and three check varieties were evaluated in hill-plots. The interyear correlations for S were very low in contrast to grain yield whereas the correlations at the same salinity level between years were significant: 0.42, 0.46, and 0.44, respectively, for control, intermediate, and high salinity. High grain yield under salinity stress appeared to be a better selection criterion for salinity tolerance than biomass yield, harvest index, orS. Analysis of accessions from 12 Iranian provinces from which five or more accessions originated gave evidence for geographic differentiation for characters related to salinity tolerance. Several accessions, differing in geographical origin within Iran, were shown to be consistently high ranking for grain yield in the control and two salinity treatments.

Field Mapping Soil Conductivity to Delineate Dryland Saline Seeps with Four‐electrode Technique

AbstractContinuing incidence of saline‐seep areas in the northern Great Plains dryland soils has created a need for detecting and delineating encroaching saline seeps before plant growth is affected. We evaluated the four‐electrode conductivity technique for field mapping surface and subsurface soil salinity under dryland conditions.Results indicated that the four‐electrode conductivity technique can be used successfully to quickly field map surface and subsurface soil salinity boundaries of existing and potential saline‐seep areas. This technique also depicted underground flow patterns of a shallow, saline ground water table.Maps of apparent bulk soil conductivity values (ECa) were used to locate the position of the recharge area in relation to the discharge (seep) area. While maps of discrete depth interval conductivity values (ECx) provided more precise information, the time required may not warrant the additional required calculations unless a portable programable calculator is available. Mapping soil salinity with the four‐electrode conductivity technique is easy, rapid, and relatively inexpensive. This technique provides information useful in making management decisions to prevent or alleviate a saline seep or other soil salinity problems.

Assessing Soil Salinity and Identifying Potential Saline‐Seep Areas with Field Soil Resistance Measurements

AbstractThe recent widespread increase in the occurrence of seep areas high in salinity in the northern Great Plains has increased the need for soil salinity research. The objective of the study was to examine the use of soil conductivity values calculated from resistance measurements obtained with the four‐probe‐Wenner electrode configuration to identify potential saline‐seep areas and estimate soil salinity in the field.Plots of apparent soil conductivity (ECa) vs inner‐electrode spacing (a) yielded different types of curves for saline‐seep areas, recharge areas, and intermediate areas. Plots of ECa vs a or ECa values alone can be used to identify potential saline‐seep areas. Significant correlations were obtained in May (r = 0.98) and August (r = 0.96) between apparent soil conductivity (ECa) and electrical conductivity of saturation extracts (ECse) showing that four‐probe soil resistance measurements can also be used to estimate soil salinity (ECse) in the field.

Boundary Flow in Laboratory Permeameters Used To Stimulate Recharge by Cyclic Water Spreading

The contribution of boundary flow to the hydraulic conductivity values obtained from laboratory permeameters employed in cyclic flood‐dry infiltration studies was evaluated. Hydraulic conductivity in the boundary zone was less than that of the inner matrix for a 2‐mm sand. Conversely, the flow rate was greatest in the boundary zone for the finer textured sandy loam soils. The divergence between the hydraulic conductivity of the inner zone and the boundary zone was greatest during the first flooding period. For both matrix zones, the changes in hydraulic conductivity within a flood cycle and with a number of flood cycles, although of different magnitude, tended to be similar and parallel. A laboratory permeameter design is presented to facilitate partitioning the relative contributions of flow in the boundary and inner zones on the hydraulic conductivity values of soils.