نشریه تحقیقات کاربردی خاک
سال یازدهم شماره 1 (بهار 1402)

The aim of this study was to investigate the effect of crop type on soil carbon accumulation in soybean (Glycin max L.) and wheat (Triticum aestivum L.) rotation, in 150 fields of soybean and 89 wheat fields in Gorgan county, in the cropping years of 2016-2017 and 2017-2018, respectively. In order to determine the amount of organic carbon and its changes, soil samples from two depths of 0-15 cm (first depth) and 15-30 cm (second depth) were prepared and then soil carbon was measured by Walkley-Black method. Spatial distributions of soil organic carbon and carbon accumulation potential at different depths and also, in the pre-sowing and post-harvest stages were performance using different types of interpolation methods in ArcGIS enviroment. The results of interpolation methods showed that Kriging was the best model for interpolation of organic carbon distribution and carbon accumulation in agricultural fields of Gorgan. Average amounts of soil organic carbon in the first depth of soybean fields were as 14.84 mg ha-1and 13.41 mg ha-1for the second depth in the pre-sowing stage. Also, it was estimated as 16.85 mg ha-1 in the first depth and 15.52 mg ha-1 for second depth, in the post-harvest stage. The amounts of soil organic carbon in the wheat fields were determined about 16.78 and 15.25 mg ha-1for first and second depths in the pre-sowing stage, respectively. Those were 13.68 and 12.30 mg ha-1for of first and second depths in the post-harvest stage sampling, respectively. The results showed that the eastern, northern, northeastern, southern, southeastern and central parts of the county had the highest carbon accumulation due to access to modern irrigation systems, more water resources, better crop management, suitable return of crop residue to the soil, develop of minimum tillage, minimizing the burning of residue and using manure. Results showed that the western and southwestern parts of the county had the lowest carbon accumulation.

Zinc (Zn) is one of the micronutrient that is in calcareous soils in low solubility forms. One of the ways of supplying Zn of the plant in these conditions is the use of microorganisms as biofertilizer. A suitable carrier is needed to supply these fertilizers. Therefore, this study was performed to isolation and identification of Zn solubilizing bacteria from soil and to evaluate the survival of the superior strain in various carriers during nine months in a completely randomized two-factor design (carrier and Time) was performed with three replications. Solid carriers included perlite, peat moss, sawdust, sugar beet waste, manure, vermicompost, azolla, biochar (azolla and apple), bran and talc. In this study, bacterial inoculants prepared with the same initial population after storage at room temperature were compared for the survival of the bacteria. For counting the bacteria in microbial carriers, MPN counting method was used in each month. The results showed that out of 24 samples of the rhizosphere soil, 15 strains of Zn-solubilizing bacteria were isolated and purified. Five isolates found to be the most efficient in solubilizing insoluble Zn compounds were examined for molecular identification. Based on gene 16S rRNA sequencing, three of the isolates belonged to the genus of Pseudomonas, and two to Enterobacter. The highest solubility index (2.28) was related to Pseudomonas fluorescens strains which were used for inoculation of microbial carriers by Ur 22 strain. The results of bacterial count in carriers showed that among the tested carriers, the highest population counted after nine months in carrier of apple biochar (5.07 log cfu g-1) and azolla biochar (5.07 log cfu g-1), and the lowest population was obtained in talc carrier (2.11 log cfu g-1). In general, it can be said that among the tested carriers, Biochar is recommended due to its good properties and cost-effectiveness.

Microplastics (MPs) have been reported as emerging contaminants. There was little information about their effect and behavior on soil properties. This study aimed to investigate the changes in exchangeable concentrations (extracted with 1 M ammonium acetate) and water-soluble (ratio of 1 to 2.5 soil to water) of sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) elements under the presence of Low-Density Polyethylene MPs particles in the soil. The experiment was performed as a factorial experiment based on a completely randomized design with three replications. Experimental factors included the amount of MPs particles (zero, 1, 2, and 4% w/w) and incubation time (3, 17, 31, 45, 90, and 180 days). The results showed that MPs particles affected exchangeable and water-soluble elements. MPs particles reduced the exchangeable amounts of Na, K, and Ca. The largest decrease was related to the level of 4% MPs. Briefly. In the level of 4%, the amount of exchangeable Na, K, and Ca decreased by 7.2, 5.7 and 2.6 %, respectively, in comparison with control soil (without MPs). On the other hand, water-soluble K and Ca under the influence of MPs particles (4% MPs level) decreased by 6.97 and 8.4 % respectively, as compared with control. MPs particles reduced water-soluble Na in the first (3 days) to fourth (45 days) incubation periods. Also, MPs particles reduced the amount of exchangeable and water-soluble Mg, but it was not significant. In summary, the presence of MPs particles in the soil, especially in higher amounts (ex: 4%), can affect the availability of cationic elements such as Na, K, Ca, and Mg.

For better management of gypsiferous soils, it is essential to have knowledge about distribution and its various characteristics. The objectives of the present research included soil genesis studies, classification, micromorphology and clay mineralogy of gypsiferous soils in Jiroft and Anbarabad regions, located in the south of Kerman Province. For this purpose, seven representative pedons were selected, described and sampled. Routine physicochemical, micromorphological and clay mineralogy analysis were performed on the soil samples. Finally, the soils were classified according to two systems: Soil Taxonomy (2014) and WRB (2015). The origin of gypsum in the soils of the studied area was gypsum marl formations at altitudes. Soils of the region were classified using Soil Taxonomy system in two suborders of gypsids and salids, and classified according to the WRB in three soil reference groups of Gypsisol, Solonchak and Slonetz. Coating and lenticular gypsum crystals and clay coating were observed in the thin sections of the studied soils. Lenticular gypsum crystals were observed in fine-textured soils. The clay coatings observed in the natric and argillic horizons were due to the role of sodium dispersion and paleoclimate, respectively. Illite, chlorite, smectite, kaolinite, sepiolite and palygorskite clay minerals were found in the soils of the regions. The presence of gypsum in the soil and evaporitic formations in the area caused the formation of palygorskite and sepiolite minerals in the soil. An inverse relationship was found between the amount of palygorskite and sepiolite with the amount of smectite, so that due to more weathering in the more humid paleoclimate and with reducing the amount of gypsum, the amount of smectite increased and that of palygorskite and sepiolite minerals decreased.

Antibiotics play a key role in the management of infectious diseases in humans and animals all over the world. Because the majority of antibiotics are not completely metabolized in the bodies of humans and animals, a high percentage of administered drugs is discharged into water and soil, thus it is known as environmentally stable organic pollutants. Based on inherent stability to degradation, antibiotics have the large range of half-lives in soil, between <1 day and 10 years. The physiochemical properties of antibiotics, soil type and climatic factors (temperature, humidity, etc.) affect the degradation of antibiotics. The remainder of these compounds, as antimicrobial agents have negative effects on soil microbial communities and, in turn, on soil health. Finally, antibiotics can be entered to the food chain through their uptake by crops and lead to antibiotic resistance in humans. However, many ambiguous results indicate that precise assessment of the fate of antibiotics and the estimation of risk of human health due to antibiotic resistance is a great challenge. In this paper, the fate of antibiotics in soil (sorption and degradation), their impact on soil microbial community function, uptake by plants and the impact on human food security are reviewed.

Microplastics (MPs) have been reported as emerging contaminants. There was little information about their effect and behavior on soil properties. This study aimed to investigate the changes in exchangeable concentrations (extracted with 1 M ammonium acetate) and water-soluble (ratio of 1 to 2.5 soil to water) of sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) elements under the presence of Low-Density Polyethylene MPs particles in the soil. The experiment was performed as a factorial experiment based on a completely randomized design with three replications. Experimental factors included the amount of MPs particles (zero, 1, 2, and 4% w/w) and incubation time (3, 17, 31, 45, 90, and 180 days). The results showed that MPs particles affected exchangeable and water-soluble elements. MPs particles reduced the exchangeable amounts of Na, K, and Ca. The largest decrease was related to the level of 4% MPs. Briefly. In the level of 4%, the amount of exchangeable Na, K, and Ca decreased by 7.2, 5.7 and 2.6 %, respectively, in comparison with control soil (without MPs). On the other hand, water-soluble K and Ca under the influence of MPs particles (4% MPs level) decreased by 6.97 and 8.4 % respectively, as compared with control. MPs particles reduced water-soluble Na in the first (3 days) to fourth (45 days) incubation periods. Also, MPs particles reduced the amount of exchangeable and water-soluble Mg, but it was not significant. In summary, the presence of MPs particles in the soil, especially in higher amounts (ex: 4%), can affect the availability of cationic elements such as Na, K, Ca, and Mg.

Mulberry is a single-stemmed tree, growing in a variety of climates. Mulberry leaves are the main source of food for silkworm, which plays a key role in silk industry. In recent decades, since the use of chemical fertilizers has caused many environmental problems, the application of organic and bio-fertilizers has increased significantly. The current study aimed to investigate the impact of growth promoting bacteria and municipal waste on enzyme changes in mulberry leaves as well as soil phosphatase enzyme. For this research, 27 mulberry seedlings were collected from Iran Silk Research Centre. This research was conducted as a completely randomized design with three replications in the research greenhouse of Guilan University. In this study, the treatments used included two levels of municipal waste (two and four percent), two levels of Pseudomonas sp. inocula (106 and 5×106 cells per liter) and control sample. Catalase, polyphenol oxidase and superoxide dismutase, chlorophyll a and b in mulberry leaves were measured and also soil phosphatase was determined. The results indicated that the application of bacteria inocula led to the increment in the amount of soil phosphatase enzyme. The results also showed that the amount of superoxide dismutase enzyme were increased from 77.2 in the control treatment to 276 μmol/g of fresh leaf tissue in the higher level of compost and bacteria treatment (second level). Furthermore, the highest amount of this enzyme was equal to 0.16 (μmol · min−1 · g−1 wet weight), which was observed in the higher level of Pseudomonas sp. inoculum (5×106) along with the higher level of organic fertilizer (4%). In general, the results demonstrated that a combination of organic fertilizer and beneficial bacteria inocula can be used instead of chemical fertilizers to provide the elements required by the mulberry plant.

Drought is one of the most frequent abiotic stresses. Organic fertilizers application such as vermicompost, reduced negative effects of water stresses. Therefore, an experiment was conducted to investigate the effect of vermicompost and moisture stress on the nutrients amount in plants and soil after harvesting, factorial based on a completely randomized design with two factors and 3 replications in Agricultural faculty of Lorestan. The first factor includes four vermicompost levels (0, 10, 20 and 30 g kg-1 soil) and the second factor includes three moisture levels (100, 75 and 55% of field capacity). The results showed that the highest shoot dry weight was observed in the surface without moisture stress and application of 30 g of vermicompost per kg of soil (5.9 g pot-1). The highest concentration of shoot Fe (65.29 mg kg-1) at the highest stress level (55% of field moisture) and 30 g of vermicompost and the highest concentration of shoot Cu (8.23 mg kg-1) At the level of water stress, there was 75% of the field capacity and application of 20 g of vermicompost. With increasing water stress, the concentration of Zn and Mn in the shoots of the plant was significantly reduced compared to the control treatment. At the level of water stress 55% of field capacity and application of 30 g of vermicompost, the highest concentration of Fe (3.55 mg kg-1) and Zn (2.70 mg kg-1) in soil after harvest was observed. Also, with increasing water stress, the concentration of Cu and Cu in the soil after harvest increased significantly. Considering the positive effect of vermicompost application in reducing the adverse effect of water stress on yield and nutrient concentration of basil, it can be a suitable fertilizer to increase the dry mater of basil plant in conditions of moisture stress.

Using efficient microorganisms can be beneficial for providing essential elements of phosphorus (P), potassium (K) and iron (Fe) to plants. In this study, the ability of some fungal species including Trichoderma asperellum, T. atroviride, T. brevicompactum, T. citrinoviride, T. harzianum, T. koningii, T. viridescens, Alternaria sp. and Aspergillus niger to release of these elements from insoluble minerals was evaluated. For this, the fungal species were added to Aleksandrov medium including tricalcium phosphate (P source) and muscovite or phlogopite (K and Fe source) and were incubated for 10-days under optimum conditions. The results showed that fungal species were able to release K from phlogopite by 103-389% and from muscovite by 21.5-178% compared to control. Among fungal species, the highest and lowest K release was observed by Aspergillus niger and T. koningii from phlogopite and by T. atroviride from muscovite, respectively. Also, the highest and lowest amount of soluble Fe was observed in medium with T. citrinoviride and Aspergillus niger in the presence of phlogopite and with T. atroviride in the presence of muscovite, respectively. The highest increase in soluble P was observed by Aspergillus niger (in the presence of both minerals), Alternaria sp., T. citrinoviride, T. coningii and T.viridescens in the presence of phlogopite compared to the control. Fungal species increased the electrical conductivity, indicating the release of elements from insoluble sources by the fungi species. There was also a significant negative relationship between P, K and Fe with pH, indicating that fungal species may have been able to release elements from the insoluble sources by producing organic and inorganic acids. In general, the fungal species have the ability to dissolve tricalcium phosphate and release more K and Fe from phlogopite than muscovite under in-vitro conditions. Thus, application of these microorganisms can be promising to provide the essential elements of plants.

Over the last three decades, there has been a general tendency to change methods in research on soil resource management from conventional and mainly qualitative methods to Quantitative ones based on spatial correlation models which are called digital soil mapping (DSM). The present study was carried out in Shabankareh plain with an area of ​​15,000 hectares with different physiographic units that are mainly used as agricultural farms in Bushehr province, Southern Iran. Target sites (172 points) were selected for soil sampling at depths of 0-30 and 30-60 based on hypothetical networking on satellite images and visual differences observed in the study area. Digital soil texture maps were drawn for both old soil texture triangle (include sand, silt and clay particles) and the new one (include Geometric mean particle diameter and geometric standard deviation of soil particle diameter). Soil texture is considered as one of the most important characteristics in determining the type and density of agricultural activities and types of land use. Two geostatistical programs include GS+ and ArcGIS and various methods of data estimators such as inverse distance weighting and ordinary Kriging method were used in this project. The results showed the strongest spatial structure class was observed in geometric standard deviation of the soil particle diameter (0.48) and the weakest in silt (0.73). The highest and lowest effective range among soil texture parameters were related to soil clay particles and geometric standard deviation of soil particle diameter with 684 and 336 meters, respectively. Number of drilled profiles (11 ones) was based on digital uniformity map. The generated digital maps can provide spatial information of important soil properties such as permeability and drainage, water holding capacity, fertility, soil erosion and salinity which increases the accuracy in the optimal management of agricultural lands.