نشریه تحقیقات کاربردی خاک
سال نهم شماره 1 (بهار 1400)

Fire has a considerable impact on vegetation and soil structure. The purpose of this study was to investigate the effect of fire on some soil physical properties of agricultural, forest, and pasture land uses in Golestan province. For this purpose, agricultural and forest land uses were selected from Gorgan province, and the pasture land use from Kalaleh as well, which were exposed to fire. Soil samples were taken from three surface (0-5cm) and subsurface depths (5-15 and 15-30 cm) for each land use in triplicate. Meanwhile, the control (non-fire) was sampled similarly. Independent t-test was carried out at p < 0.05 to compare differences between soil properties in burned and control areas. The results showed that clay content, mean weight diameter of aggregates (MWD), porosity, air capacity, structural stability index (SI), Dexter S index, and organic carbon were significantly (p < 0.05) decreased at the depth of 0-5 cm in all land uses. So that in forest, pasture, and agricultural land uses the decreasing contents were 24, 11, and 6 % for clay, 47, 41.9, and 7.4% for MWD, 10, 8, and 9 % for porosity, 34.6, 21.4, and 27.3 % for air capacity, 25.6, 7.4, and 11.3 % for SI, 19.7, 15.4, and 7.3 % for Dexter’s S index, and 8, 9.6 and 13.7 % for organic carbon, respectively, while decrement percentages of these properties were not significant at subsurface layer. Burned soils bulk density significantly (p < 0.05) compared to the control at the depth of 0-5 cm, which increment percentages of bulk density in forest, pasture, and agricultural land uses were 11, 8, and 6 % respectively, but it wasn’t significant at the subsurface layer.

Extraction and exploitation of total petroleum hydrocarbons (TPHs) led to the contamination of soil and environment. Therefore, remediation of TPHs contaminated soils is necessary. The effects of biochar produced from bagasse and zeoplant as organic amendments on some physical properties of contaminated soils with TPHs were evaluated in Ahvaz, Khuzestan Province. Systematic soil sampling was performed based on the block with completely randomize design with three replications. The soil samples were transferred to the pots (7 kg) and treatments added to the soils in the 2, 4 and 6 % levels. Afterwards, the soil moisture was adjusted on 25 and 50% of field capacity (FC). All treatments were incubated for 100 days. After incubation, bulk density, porosity, FC, PWP, TPHs, water drop penetration time and the soil penetration class were measured. Meanwhile, the variation of hydrocarbons was analyzed using Gas Chromatography (GC). Based on the GC graph, approximately 50% of normal alkanes are C13-C20. Results showed that the application of biochar and zeoplant to the soil caused to decrease of bulk density and increase the total porosity, the permeability of soil, and water retention. Moreover, the efficiency of treatments was increased by increasing of treatment application. The highest efficiency was found with 6% of biochar with 25% of moisture content, also the 6% of zeoplant enhanced the PWP from 8% in the blank to 16%. So, the application of organic treatments improved soil properties; therefore, and have an important role on sustainable management.

Water erosion is one of the most important causes of soil destruction, and it is considered a serious environmental hazard all over the world. Recently, remote sensing is customarily used in conservation and erosion projects that most of them use air photography which, despite the many benefits, bot have limitations. The present study was aimed to detect and zoning soil erosion levels using high resolution of Sentinel-2 satellite image, its integration with aerial photographs, base maps, and implementation of various classification methods, including pixel-based and object-oriented techniques. After the staff operations, atmospheric and geometric corrections, pre-processing, and processing done on images of Sentinel-2 for detecting the area of erosion in the Lighvan watershed. In order to evaluate the correctness and accuracy of each method in this study, the criterions of user and producer accuracy, accuracy and kappa coefficient were compared. Based on the results, the supervised tuning method with user accuracy equal 77.78 and 33.33, has the highest and lowest accuracy for classification using spectral angle map algorithm and Mahalanubis distance, respectively. The maximum of overall accuracy and kappa coefficients, 72 and 62 percent, respectively, indicate the medium accuracy of the produced maps with pixel based algorithms. The results of object-oriented processing show that based on user and producer accuracy, object-oriented methods have increased accuracy (12 %) compared to pixel-based methods. Classification results with object-oriented algorithms and based on overall accuracy, 88 and 84 percent, respectively, for the brightness and the combination of brightness and slope, and the kappa coefficient for these two algorithms was 0.86 and 0.79, respectively. This result represents an acceptable increase in classification accuracy in the use of object-oriented algorithms compared to pixel base algorithms.

Remediation of heavy metals contaminated soils by plants is one of the most cost-effective and environmentally friendly methods. In some cases, useful soil microorganisms are used to increase the plants efficiency in heavy metal remediation. The aim of this study was to investigate the effect of rhizospheric pseudomonads on increasing the phytoremediation efficiency in copper (Cu)-contaminated soils. The first experiment was carried out in a completely randomized design in three replications with 11 plant treatments (Maize (Zea mays), sorghum (Sorghum bicolor), wheat (Triticum aestivum), canola (Brassica napus), Fennel (Foeniculum vulgare), Amaranth (Amaranthus), Salvia (Salvia officinalis), Zygophyllum (Zygophyllum), Ajwain (Trachyspermum ammi), alfalfa (Medicago sativa) and pumkin (Cucurbita)). The highest Cu concentration and uptake  were related to Zygophyllum with 173 mg kg-1 and pumkin with 222 µg pot-1, respectively. Five plants including pumpkin, maize, wheat, canola, and Zygophyllum were selected based on the highest Cu concentration and uptake of  for the second experiment. The second experiment was designed in a completely randomized design with two factors including plant types at five levels (pumkin, maize, canola, wheat and Zygophyllum) and three levels of bacteria (non-bacterial inoculation, Pseudomonas putida PA2 strain, Pseudomonas fluorescence PA3) in three replications. In this section, the shoots and roots dry weight; Cu concentration and uptake in shoots and roots, as well as the chemical changes of the Cu in the rhizosphere were investigated. The use of both strains of the bacteria significantly increased the dry weight, concentration and uptake of Cu in shoots and roots compared to the control. Among the plants, pumpkin had the highest uptake of Cu in shoots due to high biomass (90.2 µg pot-1) (the most effective in phytoextraction) and maize due to its high root weight had the highest Cu uptake (428 µg pot-1) (effective in high Phytostabilization). Investigation of the chemical forms of Cu in the rhizosphere showed that inoculation by PA2 and PA3 growth-promoting bacteria increased 41.9 and 37% of soluble and exchangeable forms of Cu respectively, and decreased the residual form of copper up to 7.05 and 6.41%. The overall results showed that the growth-promoting bacteria play an effective role in increasing the phytoremediation, especially the phytoextraction and pumpkin with the highest Cu uptake was the most efficient plant in the Cu phytoremediation in this study.

Soil fertility represents the soil ability to provide optimal plant growth conditions. Information on soil fertility status and preparation of related maps, plays an essential role in sustainable agricultural planning, maximizing economic benefits, maintaining soil quality, and preventing environmental degradation.In order to evaluate soil fertility status in some drylands in south of western Azerbaijan province and north of Kurdistan province, 101 samples were randomly collected and different soil properties such as pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), and total nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were measured.Nutrient Index Value (NIV) was used to interpret the results and map soil fertility.The results showed that 100% of the soil EC and pH of areas were classified in the low and high classes, respectively.Organic carbon (OM) and CCE were in the medium class in 72% and 61% of the areas, respectively.Total Nitrogen in 94% of areas in medium class, available P in 94% of areas in low class, K in almost 100% in high class, available Fe in 88% of areas in low class, Zn in 33% in low class, 39% in adequate class, and 28% in high class, Cu and Mn available in 100% of areas are in low class.It can be concluded that NIV method is useful to evaluate soil fertility status and its predictions conform to the reported critical level for rainfed wheat.

Continuous use of monoculture systems and excessive tillage has degraded agricultural soils in many regions of Iran. The short-term impact of cover crops on selected soil properties was investigated in a field study in 2018. The experiment was laid out as complete randomized block with three replications. The four experimental treatments included, monoculture of oat and monoculture chickling pea, their mixture, and no cover crop as control. Highest and lowest aerial biomass were 198.1 gm-2 and 124.1 g m-2 and obtained from mixed cover crop and sole chickling pea, respectively. The higher biomass resulted in significant weed suppression, compared with control. Weed dry weight reduced by 33.04% and 41.12% in oat monoculture and mixed cover crops, respectively. The highest soil organic carbon (1.21%) and highest microbial population (6.5 × 105 per gram of soil) were obtained from mixed cover crop experimental plots. Cover crop mixture, and monoculture of oat and monoculture chickling pea reduced soil compaction by 51.5%, 50.7%, and 49.1%, respectively. However, soil bulk density, soil porosity, and rate of water infiltration were not affected by cover crop treatments. Results obtained in this study indicated that short-term changes in some soil properties are related to both, biomass and cover crop species. Overall, a mixed of cover crops was more influential on changing soil properties.

Salinity is a major environmental stress that limits plant growth and productivity in Iran. Olive (Olea europea L.) is one of the most valuable and widespread fruit trees in the Mediterranean area. In the last years, the surface of olive orchards has increased considerably in Iran. Furthermore, cultivars used in these orchards are often foreign and little is known about their behavior under Iran climate conditions, especially about their tolerance to salinity. Hence, in order to study the effects of NaCl salinity on some morphological and physiological properties of one-year-old rooted cuttings of two olive cultivars (Mission (a foreign cultivar) and Mary (one of the most important Iranian cultivars)), a pot experiment was conducted in factorial based on randomized complete blocks design with four replications. Saline treatments were imposed by irrigation with water containing 0, 25, 50, 100 and 200 mM of NaCl. The results showed that NaCl salinity has significant effects on the parameters. The plants grow parameters (plant height, number and area of leaves, number and length of axillary shoots, stem diameter, fresh and dry weight of leaves and stems, dry weight of root) were decreased by increasing of NaCl concentration in irrigation water. Relative water content (RWC), chlorophyll content and leaf potassium concentration were decreased as well. However, converse effect was found in proline, total soluble sugars (TSS), and concentration of Na and Cl in leaves. Overall, the findings of this study showed that cv. Mission because of higher potassium concentration, chlorophyll content and RWC, higher accumulation of proline and TSS and lower concentration of Na and Cl in leaves was more resistant to salinity than cv. Mary.
 
Keywords: Growth parameters, Olive (Olea europea), Proline, Relative water content, Salinity

The present study was performed in order to investigate the effect of plant growth promoting microorganisms on distribution of phosphorus forms in a calcareous soil under maize (Zea mays L.) cultivation and to evaluate these forms relationship with soil microbial characteristics. The experiment was carried out as a completely randomized design including control (without microbial inoculation), soil inoculation with Staphylococcus hominis and Brevundimonas sp., Piriformospora indica and mixture of fungus and bacteria treatments at five replications under greenhouse conditions. Maize seeds were planted in 3 kg pots and different forms of mineral and organic phosphorus, some microbial characteristics (microbial biomass carbon and phosphorus and phosphatase activity) and the phosphorus uptake in the plant were measured after three months of cultivation. The results illustrated the influence of microbial inoculation on mineral and organic forms of phosphorus as well as phosphorus uptake in the plant. The decreasing order of phosphorus mineral components was as Ca10-P> Ca8-P> Ca2-P> Al-P> Olsen-P> Fe-P> OCC-P in the control soil and this trend obtained as Ca10-P> Ca2-P> Olsen-P> Al- P> Ca8-P> Fe-P> OCC-P in the soil containing a mixture of microbes. Available phosphorus components, including Olson-P, dicalcium phosphate, and relatively stable and unstable organic phosphorus had positive and significant correlation with phosphorus uptake by the plant. There was a positive correlation between extracted Olsen- phosphorus and microbial phosphorus and carbon biomass, and alkaline phosphatase activity. In general, the results showed the positive influence of microbial inoculation, especially fungal and bacterial mixture, on the enhancement of phosphorus availability for the plant. The highest values of extracted phosphorus by Olsen method and phosphorus uptake by plant were found at 34.02 mg kg-1 and 11.52 mg pot-1, respectively, in the mixture of fungi and bacteria treatment with significant difference (p ≤ 0.05) compared to other treatments.

Over the past few decades, fractal geometry has been extensively used as a powerful tool in characterizing porous media properties and hydraulic soil modeling. In this study, the applicability of fractal dimension values derived from particle size distribution (DPSD) and soil moisture curve (DSMC) in estimating saturated hydraulic conductivity (SHC) were compared and evaluated using the new fractal Ghanbarian et al. (2018) model. For this purpose, eight sandy samples were prepared in cylinders with an internal diameter of 4.4 cm and a height of 5 cm. The particle size distribution was determined by the combination of dry and wet sieve methods. Water content was measured in eight tension heads from zero (saturation) to 10 kPa in the sandbox and at 19 higher tension heads, from 18 to 1500 kPa with the pressure plate. For all samples, the bulk and particle density, total porosity, and SHC were also measured. The mass fractal (DPSD) and pore space fractal (DSMC) dimensions were determined using the particle size distribution and soil moisture curve (SMC) data, respectively. The root mean square error (RMSE) of fitting SMC by applying the DSMC and DPSD were found in the range of 0.004 to 0.022 and 0.009 to 0.069, respectively. The results showed that the DSMC fits the SMC with higher accuracy than the DPSD and the DPSD had no specific correlation with the DSMC of the samples. The root mean square logarithmic error (RMSLE) for the estimated values ​​of SHC using DSMC and DPSD was found to be 0.286 and 0.306, respectively. Although there is no significant difference between the two fractal dimensions, the application of DSMC values ​​as an image of the microscopic properties of the porous medium and its combination with the percolation theory has improved the accuracy of estimating the SMC and SHC.

Climate change is a major threat to sustainable development and food security due to the impact of greenhouse gases of the Earth's atmosphere, especially in arid and semi-arid regions of the world such as Iran. Carbon sequestration in soils and plant ecosystems is one way to overcome this problem. Organic carbon content in soil is three times higher than carbon in all plant tissues and twice as high as atmospheric carbon. In this study, the effects of crop production and manure and straw application on carbon sequestration were evaluated, based on some soil physical and chemical properties. Soil samples (n = 308 in total) were collected from the surface depth (0-30 cm). Soil properties such as soil texture, pH, electrical conductivity, organic carbon, bulk density, carbon sequestration and etc. were estimated. Data were analyzed using SPSS software. Descriptive statistics, mean, standard deviation, etc. were used to determine the distribution of specimens. Stepwise regression was used to present the model. Analysis of the results showed the significant relationship between carbon sequestration and all soil properties, except sand. Soil carbon sequestration in the third crop year (onion) increased from 4.84 to 5.68 kgm-2. In the onion crop grown in the third year after wheat, straw produced by organic fertilizer increased by 30% and organic fertilizer by 70%. Finally, carbon sequestration was mapped for both crops using locomotor data and Arc map software.