APPLIED SOIL RESEARCH
Year:2019 | Volume:7 | Issue:1 |Papers Count:15

Land-use change is one of the most important factors influencing soil microbial communities, which play a pivotal role in most biogeochemical and ecological processes. In order to determine the effect of land use on the relative abundance and composition of soil bacterial communities by using Real-time PCR, a study was carried out in three different land uses (orchard land, farmland and shrubland) in Jiroft plain, Iran. Number of 12 surface soil samples were collected from each land use and some soil physicochemical properties were measured. The NucleoSpin® Soil kit was used for extraction and purification of DNA from soil samples. Quantitative comparison of the concentration and melting temperature of 16S rDNA amplicons, respectively, for assessment of the relative abundance and composition of soil bacterial communities in different land uses were performed by using Real-time PCR system and based on the relative standard curve method. The results related to the concentration and quality of soil DNA indicated that extraction of DNA from soil samples by using NucleoSpin® Soil kit was favorable. As the results of Kruskal-Wallis nonparametric ANOVA, land use had significant effect on the relative abundance and composition of soil bacterial communities at the level of 5%. Means comparison showed that the relative abundance of soil bacterial communities in orchard land use was higher than that of two other land uses. Furthermore, the composition of soil bacterial communities in orchard and farm land uses was significantly different from shrub one. It can be concluded that land-use changes in Jiroft plain from shrubland to orchard land, and from shrubland to orchard land and farmland have caused an increase in the relative abundance as well as a significant change in the composition of soil bacterial communities, respectively.

Assessing biological indicators of soil quality is crucial to evaluation of ecological sustainability of agroecosystem. This study aimed at assessing the effects of four years of different tillage practices (no tillage, minimum tillage and conventional tillage) with and without canola cover crop on selected biological indicators of soil quality and sunflower yield in Dastjerd, Hamedan; A randomized complete block design with factorial arrangement and three replications was conducted. All the measured properties, including soil organic carbon, available P, basal microbial respiration, protease and phosphatase activity and sunflower seed yield were significantly (P

Soil erodibility is a dynamic aspect that varies over time and with plough, animal’ s activities and biochemical factors resulting in a major environmental threat to the sustainability and productive capacity of agricultural areas. In Universal Soil Loss Equation (USLE), soil erodibility factor (K-factor), as an effective parameter in water erosion is a function of particle size distribution, organic matter, structure and permeability. In the present study, the spatial distribution of the amount of K-factor was investigated in the Nazlou Chai Watershed in Urmia, West Azerbaijan using geostatistics. Then soil samples were taken from 1 km by 1 km square grid over 64 location, and the amount of K-factor was calculated in the USLE model. The results showed that K-factor was ranged from 0. 029 to 0. 079 (T h MJ-1 mm-1). The spatial variation of K-factor was best fit to the exponential model and showed a moderate spatial structure. The studied soils were categorized in low and very low erodibility classes. The quantitative amounts of erodibility were categorized based on slope classes and the highest value observed for 5-8% slope that belongs to dry farming land use. Also K-factor showed various values in different hydrological groups, where group A showed the least and group D showed the highest amount. It seems that inappropriate soil management in both hilly areas and dry farming lands is one of the main causes of soil damage and an increase of soil erodibility.

Abstract Earthworms are as the most important soil forest ecosystem engineers. Present research was considered to study the reaction of earthworm group's (epigeic, anecic and endogeic) in topsoil to variability of ecological characters (litter C, litter N, litter C/N, soil C, soil N, soil C/N, and pH and moisture) in Noor Forest Park. Litter and soil samples were taken, with microplots of 30×30×15 cm, under tree canopy of Alnus glotinusa, Ulmus glabra, Popolus caspica and Parrotia persica species. Earthworms were collected during soil sampling, washed in water and weighed. Biomass was defined as the weight of the worms after drying at the labratory. Results showed that the soil under Alnus glotinusa has high abundance and biomass of epigeic (0. 3 n/m2 amd 3 g/m2 respectively) and endogeic (1. 4 n/m2 and 14 mg/m2 respectively). Whereas any epigeic and endogeic were not found under Parrotia persica. The least density and biomass (0. 5 n/m2 and 0. 5 mg/m2 respectively) of anecic earhworms were recorded under Parrotia persica. The results of this research are indicating of positive role of Alnus glotinusa species, related to high litter N, on biological index of soil quality that can be considered to restore of degraded parts in the northern Iran.

Near-saturated soil hydraulic conductivity (Ks) is a key property for several purposes including simulation of hydrological processes, determination of unsaturated soil hydraulic conductivity function and modelling water flow and solute transport. Since it is soil structure-dependent, field measurement techniques should be used to minimize disturbance of the sampled soil volume. Because of high spatiotemporal variability of Ks, replicated measurements need to be carried out, so that, the method to be applied should be simple and rapid enough as the simplified falling head (SFH) technique is. Alternatively, pedotransfer functions (PTFs) could also be utilized for indirect prediction of Ks through the surrounding soil attributes. The objective of this study was to test some new inputs to predict the Ks of salt-affected soils adjacent to Lake Urmia. A 32 cm diameter ring was used to determine Ks by the SFH technique in soils with different salinity (electrical conductivity of saturated extract, ECe = 0. 1 – 95. 3 dS/m) and sodicity (exchangeable sodium percentage, ESP = 4. 0 – 70. 9 %) levels. A total of 190 SFH runs were carried out, adjacent to each of which, some undisturbed soil cores (5 cm in height by 5 cm in diameter) and disturbed soil samples were randomly collected from the surface soil and were analyzed for their physicochemical properties. The studied soils mainly had moderate (≈ 40%) to moderately rapid (≈ 48%) conductivities. Correlation and stepwise regression analysis showed that Ks was correlated negatively with bulk density (ρ b) (r =-0. 205), index of crusting (Ic) (r =-0. 180), and degree of compaction (SDC) (r =-0. 206) (P ≤ 0. 01) and positively with structural stability index (SSI) (r = 0. 184) and geometric mean diameter of soil aggregates (GMD) (r = 0. 157) (P ≤ 0. 05). Furthermore, the Ks had negative correlation with both soil ECe and ESP.

In order to determine the elements and heavy metals in water and areas in various plants, the experiment was conducted during the years of 2014 and 2015 in form of factorial based on randomized complete block design. The first factor was included two levels of water (pit water and sewage water) and the second factor was involved three regions (Tabriz, Maragheh, and Bonab) and the third factor was included three crops (onions, tomatoes and alfalfa). 36 treatments were studied over two years in three replications. The results showed that there are significant differences among studied waters in terms of element amount. But the interaction of year and no significant difference waters but no significant difference was observed between interaction of year and waters. The results among the studied plants in terms of element amount demonstrated that there are significant differences among plants in terms of elements amount and also significant differences were observed for interaction of year and plant in majority of the studied traits. By studying the three regions in terms of elements amount; it was observed that there are significant differences among the regions. Significant difference was observed in majority of the studied traits for interaction of year and region. The results of mean comparisons with Duncan method indicated that sewage water had the highest amount of elements and onion had the greatest amount of elements and Bonab was the most polluted region. The correlation results showed that there was significant negative correlation between yield and heavy metals.

Splash erosion is one of the most important kinds of water erosion. Splash of soil particles may affected by some factors especially antecedent rainfall event. Up to now, there isn’ t any study on the effects of antecedent rainfall on splash erosion in the next rainfall. This study was conducted to investigate the effect of antecedent rainfall on the particles splash in a marl soil. Toward this, aggregates with a diameter of 6-8mm were taken from a marl soils under fallow condition in 2016. Aggregates were packed in 24 boxes with 30cm× 40cm dimensions and 30cm depth to investigate effect of eight rainfall durations levels at three replications. Simulated rainfall was applied to soil samples with eight durations (0, 7, 14, 21, 28, 35, 42 and 49 min). Aggregate breakdown and soil water content were determined in the soil samples after one day. After one day, soil boxes were placed under the same rainfall with a constant intensity of 40 mm h-1 for 15 min. Based on results, duration of antecedent rainfall significantly affected the aggregate breakdown and increased the soil water content. The longest rainfall duration (49 min) appeared the highest aggregate breakdown (21. 72%) as well as soil moisture content (29. 08%). The amount of splash erosion in the next rain event was significantly influenced by the changes in two soil variables, i. e. aggregate breakdown (P <0. 05) and soil water content (P <0. 01), implied by the antecedent rainfall. Multiple linear regression analysis showed that among the two soil variables, antecedent soil water content is the most important factor determining the splash erosion variation in the next rain event (R2 = 0. 83, P<0. 01). The splash erosion in each rain event could be reliably estimated by determining the antecedent soil water content.

Electrokinetic soil remediation is one of the innovative methods for decontamination of heavy metals from polluted soils. However, employing the method on soils with great adsorption capacity for heavy metals at field conditions needs to be studied thoroughly. In this research a loam soil spiked with Lead (Pb) used to investigate electrokinetic remediation at field-scale in three depths (0, 15 and 30 cm) on experimental plots. After contamination with Pb nitrate solution (1 g l-1), the soil had large amount of Pb (109. 5, 102. 1 and 87. 3 mg kg− 1 in three depths 0, 15 and 30 cm, respectively). All experiments were imposed with a constant voltage gradient of 1 V/cm in 10 days period in saturation condition at a field in Tabriz area, North West of Iran. In this study effect of different electrolytes (distilled water, Acetic acid 0. 005 M) was studied on the Pb removal efficiency by electrokinetic remediation. The results showed that removal efficiencies for Pb were influenced by the type of electrolyte solution. After applying electrical current for 10 days, mean metal removal efficiency of Pb in distilled water treatment for three depths (0, 15 and 30) were 18. 15%, 18. 05% and 20. 85%, respectively. The mean Pb removal from the soil in acetic acid treatment in three mentioned depths were 22. 0, 21. 55 and 24. 05 %, respectively, which represented 3. 85, 3. 5 and 3. 2% increase in removal efficiency compared to the distilled water. High lime content (20. 1%) of the examined soil hindered the increase in removal efficiency with acetic acid solution. Furthermore, the pH changes along the soil plots showed an increasing trend from the anode to the cathode. In acetic acid treatment a greater reduction of pH was observed in the anode side.

Managing and monitoring of salinity is one of the most important affair in agriculture, especially in arid and semi-arid area. For this purpose, the use of new technologies like remote sensing and GIS is inevitable. The investigation of relationships between different soil parameters using satellite data is an effective step in predicting the electrical conductivity of soil saturation extract. In this research, using multivariable regression method based on relationship between topographical properties and obtained indices from Landsat 8 satellite, the prediction of the electrical conductivity of soil saturation extract was studied in Urmia plain. For this purpose, firstly 40 samples were taken from 0-30 cm soil depth and their electrical conductivity of soil saturation extract (ECe) were measured. After performing the necessary processing on satellite images and determining the ground surface points, pixel values in the different bands were extracted. In the present research, the data was divided into two series including training (80% of data) and validation data (20% of data). The relationship between satellite data and the obtained results from the region soil tests was extracted using the multivariable linear regression methods and the accuracy of the model was evaluated by factors such as R-squared, standard error of the mean, adjusted R-squared and Durbin Watson statistic. The results showed that for the obtained model, the error indices including the correlation coefficient, standard error of the mean, adjusted R-squared and Durbin Watson statistic were calculated 70. 3%, 10. 03%, 61. 8% and 1. 709 respectively. Finally, the model was run using test data and for its evaluation the indices including Geometric Mean Error Ratio (GMER), R-squared (R2) and Root Mean Square Error (RMSE) were employed so that the mentioned indices were measured 0. 867, 0. 638 and 0. 354 respectively. These results show good efficiency and accuracy of the model

In order to study the effect of arbuscular mycorrhizal fungi on morphological and physiological characteristics of maize in different levels of phosphorus fertilizer, a greenhouse experiment was carried out as factorial arranged in completely randomized design with three replications at Islamic Azad University Miyaneh Branch, Iran. The experimental treatments were mycorrhizal inoculation with Glomus mosseae (inoculation and non-inoculation) and four levels of phosphorus fertilizer (control, 13, 26, and 39 kg P per ha). Results showed that the highest values of wet and dry biomass (224. 08 and 172. 47 g Plant-1, respectively) were obtained from mycorrhizal inoculation and 39 kg P per ha. Also, the lowest values of wet and dry biomass (120. 74 and 95 g Plant-1, respectively) were obtained from control (without inoculation and phosphorus fertilizer). The highest values for length, weight, and number of ears (23. 22 cm, 116. 32 g and 4. 25, respectively) were obtained in mycorrhizal inoculation in 39 kg P per ha. Finally, the results of this research showed that applying arbuscular mycorrhizal fungi increased amount of biomass, chlorophyll, and leaf phosphorus concentration and improved morphological and physiological characteristics of maize. Also, absorption of phosphorus and plant yield were increased by applying a low amount of phosphorus fertilizer.

Gypsiferous and calcareous soils comprise important parts of soil resources in arid and semiarid areas of south of Guilan province. This study was conducted in order to investigate gypsum and lime in the soils of hilly lands of Aliabad region in Guilan province using soil thin sections. Soil samples were taken as air-dried undisturbed clods from gypsiferous-salty and calcareous parent materials with three replicates at two slope positions (back slope and foot slope) from surface (0-20 cm) and subsurface (20-40 cm) depths. Results showed that the soils with gypsiferous-salty parent material had heavier textural class than the calcareous soils. The results of micromorphological studies showed that the number of channel and chamber voids and excrements is higher in calcareous soil due to the presence of larger pores and more biological activity. Micromorphological pedofeatures of gypsiferous-salty soils include the forms of gypsum interlocked plates, gypsum lenticular crystals, gypsum pendant, infilling of gypsum as dense complete and incomplete, and loose discontinuous in voids and channel walls and hypo-coating of iron and manganese and in calcareous soils include excrements, hallow iron and micritic nodules, rock fragments, gypsum and calcite pendant and different forms of pedogenic calcite as columnar, cluster, needle, micritic and sparitic. The fine fraction in both soils were mainly crystallitic b-fabric and locally stipple speckeld and undifferentiated b-fabric. The micromorphological index for soil evolution (MISECA) showed that both soils had weak development. Results of clay mineralogical study showed that chlorite, illite, vermiculite, smectite and hydroxyl-interlayer minerals were prominent in both soils. Palygorskite was found only in the soils with gypsiferous-salty parent material.

In this study, the effect of salinity on yield, phosphorous efficiency indicators, and some elements concentration in the root and shoot of corn (Zea mays L. ) was evaluated. The efficiency of phosphate-solubilizing microorganisms and mycorrhizal fungi was further determined in adjusting salinity impacts on the studied plant. A completely randomized factorial design carried out at greenhouse conditions. The first factor was salinity (non-saline (NS) and salinity of 4. 5 dS m-1 (S)) and the second factor was microbial inoculation including control (no inoculation), soluble phosphorus (P), mycorrhizal inoculation (M; Glomus), inoculation of phosphate solubilizing bacteria (PSB; Pseudomonas fluorescens), phosphate solubilizing fungi inoculation (PSF; Aspergillus niger), dual inoculation of mycorrhiza and bacteria (MB) and dual inoculation of mycorrhiza and fungi (MF). At the end of growing period, some plant growth indicators and nutrient concentrations of plant shoots were analyzed and the phosphorous efficiency indicators were calculated. Results showed that the salinity had a significant impact on all of measured properties except zinc. The highest amounts of shoot length (78. 9 cm) and stem diameter (1. 0 cm) were observed in the soluble phosphorus treatment. We also found a significant increase in phosphorous, iron, zinc, copper, and manganese content, shoot length and stem diameter of plants inoculated with mycorrhiza and bacteria as well as in dual inoculation of AMF and PSM condition compared to non-inoculated plants. Bacteria and mycorrhizal treatments increased shoot length amount by 1. 90 and 1. 20 times compared to control, respectively. Aspergillus fungi and AMF treatments increased shoot zinc content by 40. 98 and 85. 65% compared to control, respectively. It could be concluded that microbial inoculation increases corn resistance to salinity condition through improving its nutrients uptake.

High costs of fertilizers production and environmental pollution due to their application make it necessary to use other sources especially biofertilizers. The purpose of this study was to determine capability of bacteria Pseudomonas fluorescence survival as one of phosphate solubilizing and plant growth promoting bacteria on different organic and inorganic carriers including vermicompost, perlite, rock phosphate, and four formulations of them, as well as, to investigate their effects on growth indices of wheat. The experiment was performed through complete randomized block design with four replicates, seven inoculants and two fertilizers (simple and triple superphosphate) treatments. Results showed that although triple super phosphate treatment was the best regarding to its positive effects on plant chlorophyll, plant height, phosphorus content in the shoot, and shoot and root dry weight attributes, it had no significant difference with inoculants containing vermicompost (P>0. 05). Regarding to the iron (Fe) and zinc (Zn) in the shoot, vermicompost inoculant was superior to the other treatments, and regarding the shoot Zn this difference was significant compared to the fertilizer and control (P<0. 05). Perlite+ vermicompost inoculants implied, respectively, a 10. 6 and 14. 5% increase in chlorophyll content and plant height, in comparison with the control. Vermicompost+ rock phosphate and vermicompost inoculants increased root dry weight by 28% and 24. 5%, respectively (P<0. 05). Vermicompost inoculants increased the shoot dry weight, phosphorus in shoot, Zn in shoot and Fe in shoot by 6. 58%, 27%, 26. 3% and 24. 83% in comparison with the control, respectively (P<0. 05).

Soil erosion is an important environmental hazard with on-site and off-site effects that gradually cause soil quality deterioration, land degradation, surface water contamination, and reduction of dam’ s reservoirs capacity and finally threats the human food security. The soil loss due to the crop harvesting (SLCH) is a form of soil transportation processes which has attracted a little attention in comparison with the other types of soil erosion. Therefore, the objective of this study was to determine the soil loss by potato harvesting process in the Ghorveh-Dehgolan plain, Kurdestan province. For this purpose, twenty samples, each containing 5 kilograms of potato, were collected from rainfed and irrigated farmlands of the study area. The samples were washed out in the laboratory to separate the soil from potatoes and then the suspension was filtered and dried to determine the SLCH. The results indicated that the amount of SLCH ranged from 13. 4 to 40. 4 g kg-1 of potato. The one-way ANOVA test indicated that there was a significant difference between SLCH of rainfed and irrigated farmlands (p<0. 05). Cluster analysis was also demonstrated that there was a weak correlation between SLCH and land use in the study area. The estimated SLCH from 80490. 4 ha of potato farmlands during the past 10 years was 72374. 53 Mg which is equal to 7237 Mg year-1. The average SLCH ranged from 0. 66 to 1. 14 Mg ha-1 during the harvesting processes. The results of this study confirmed that the SLCH has the same importance as the other types of soil erosion and should be considered in soil conservation activities.

Potassium content in tobacco leaves is highly affected the quality of tobacco and considered the important indicator for determining the tobacco leaf quality. The objective of this study was to investigate the relationship between different soil K forms (soluble, exchangeable, non-exchangeable, mineral and extracted with aqua-regia extractable) with quantitative and qualitative characteristics of tobacco. Nineteen surface soil samples were collected from tobacco cultivated areas of Golestan, Mazandaran and Guilan provinces. Physical, chemical properties and different forms of potassium in the soils were measured. A pot experiment in a completely randomized with three replications for the soils without application of potassium fertilizer was design to study the potassium uptake by tobacco. The results showed the lowest amounts all potassium forms in Guilan soils (except exchangeable potassium) and the highest amounts in Mazandaran soils. The effect of soil type on all the morphological and chemical characteristics of tobacco was significant at P<0. 01. Soluble and exchangeable potassium were highly correlated with morphological and chemical characteristics of tobacco. The amount and also the ratio of soluble to total potassium in percent) at P<0. 01 and exchangeable potassium at P<0. 05 had the relatively strong correlation with the tobacco potassium percentage. Also, because the amount of different forms of potassium did not explained the reason of potassium changes in the tobacco plant. Therefore, it is suggested to use the ratio of soluble and exchangeable potassium to total potassium (in percent) for more precise potassium fertilizer recommendation.