نشریه مدیریت خاک و تولید پایدار
سال چهاردهم شماره 1 (پیاپی 47، بهار 1403)

In recent years, due to the large amount of agricultural wastes, the production and use of biochar as a carbon-rich material has become very important in order to recycle plant residues, reduce greenhouse gas emissions, preserve nutrients and remove pollutants and heavy metals from the soil. This research was conducted with the aim of investigating the effect of pyrolysis temperature, type of biomass and modification with mineral salts on the characteristics of produced biochars.

To carry out the research, a factorial experiment was conducted in the form of a completely randomized design with three replications. The experimental factors include the type of feedstock in 2 types (sugarcane bagasse and rice straw), the pyrolysis temperature in 2 levels (300 and 500 ºC) and the type of biochar΄s modification in 4 models (control or without modification, modification with FeCl3, ZnCl2 and KH2PO4). At first, biochars were prepared (16 samples in 3 replicates) and then their physicochemical properties were measured and analyzed.

The results showed that with the increase of pyrolysis temperature in control and all modified biochars, the amount of ash, fixed carbon, electrical conductivity (EC), acidity (pH), specific surface area (SSA), carbon content and C/N ratio increased and yield, volatile matter, cation exchange capacity (CEC), oxygen and hydrogen content decreased. In rice straw biochars (control and modified), oxygen content, O/C and O+N/C ratio at both temperatures and CEC value at 500 ºC are higher than sugarcane bagasse biochars and Its SSA was less. Modification with mineral salts increased the amount of ash, yield, CEC, SSA, EC, oxygen content, O/C ratio and decreases pH, carbon, nitrogen and hydrogen content in biochars produced at both temperature levels and two types of biomass. The highest amount of CEC was observed in sugarcane bagasse biochar produced at 300 ºC modified with phosphorus (58.94 cmol.kg-1) and the highest SSA in sugarcane bagasse biochar produced at 500 ºC modified with iron (94.49 m2/kg). The rice straw biochar produced at 500 ºC without modification with a pH of 8.83 had the highest pH value, and the rice straw biochar produced at 500 ºC modified with iron with EC of 9.23 had the highest EC value and the highest percentage of ash (49.07%) compared to other biochars. The most fixed carbon was related to unmodified 500 ºC sugarcane bagasse biochar (51.4%) and 500 ºC sugarcane bagasse biochar modified with zinc (48.7%). Th 300 ºC rice straw biochar modified with iron had the lowest percentage of fixed carbon and the highest ratio of H/C, O/C and O+N/C and in biochar modified with zinc produced at 500 ºC, these ratios had the lowest value compared to other biochars, which probably indicates their greater stability.

The results of this research showed that the biochars produced at 300 ºC, especially the types that modified with phosphorus and iron, have properties that are expected to remove pollutants from water and soil and improve soil fertility, and the biochars prepared at 500 ºC, especially the types that modified with zinc, have the characteristics required for application in order to carbon sequestration in the soil. Of course, more research needs to be done to provide more accurate results. In general, the use of mineral salts to modify biochar can be effective in optimizing its characteristics, according to the purpose of application.

Heavy metals are the common pollutants of soils, which pose a potential threat to the public and particularly children's health. Therefore, this study was conducted to identify, determine and evaluate potential ecological risk of Cd, Pb, Ni, As,Cr and V in surface soil samples of the disposal site of the wastes resulting from the activity of oil refining units (Nuruddin Abad, Garmsar) in 2022.

In this research, after the preliminary study, field survey and considering the studied area is relatively homogeneous and there is no source of pollution in the area and for many years wastes of colored soil and acid sludge has been discharged in this area, random sampling method was used. Surface soil compound samples were collected from 8 selected stations in the study area from a depth of 0-15 cm and after preparation and acid digestion of the samples in the laboratory, the content of cadmium, lead, nickel, Arsenic, mercury, selenium, chromium, barium, vanadium, antimony, silver and beryllium were measured by atomic absorption device with Varian graphite furnace model GBC AA 932. In order to estimate the intensity of pollution Contamination factor (Cf), Degree of Contamination (Cd), Modified Degree of Contamination (mCd), Pollution Load Index (PLI), Geoaccumulation index (Igeo) and Ecological Risk Index (RI) were computed. Furthermore, all statistical analyses were performed by SPSS software.

Based on the results, the mean content of Cd, Pb, Ni, As,Cr and V in soil specimens was 1.69, 66.71, 28.43, 8.64, 25.38 and 18.85, Respectively. On the other hand, the soil quality of the study area varied between "very high degree of pollution" in stations 1 to 5 to "extremely high degree of pollution" in stations 6 and 7 based on the Degree of Contamination and "non-polluted" to "severely polluted" based on the geo-accumulation index (I-geo) values. Also, the results of the Modified Degree of Contamination showed that Pb and Ni pollution is in the medium degree of pollution and Cd, As,Cr and V pollution is in the high degree of pollution. In addition, by calculating the ecological risk potential factor (Er), it was determined that Cd and As are the most important pollutants responsible for ecological risks, and the trend of changes in the potential ecological risk of metals in the region was evaluated in the order of Pb<Cr<Ni<As

Comparison of the average content of the metals identified in the studied samples with the permissible limits of the soil resource quality standards of Iran's Environmental Protection Organization showed that the amount of lead and cadmium metals is more than the permissible limit and the amount of nickel, arsenic, chromium and vanadium was less than the allowed limit. As the mean contents of a number of identified compounds were higher than the permissible limit, applying corrective measures and clean the soil based on the soil pollution cleaning standards of Iran's Environmental Protection Organization is recommended for the environmental and human health aspects.

Determining the amount of soil erosion and its spatial distribution can effectively provide appropriate management practices to reduce erosion problems. Direct measurement of soil erosion takes a lot of time and money, and results are often regional and limited. This issue has led to the development of various models for estimating soil erosion and sediment production. Since most of the watersheds in Iran lack sufficient and accurate information, models that require relatively few inputs make more sense than models with high inputs. Along with empirical and process-based models, a number of erosion estimation models are known as hybrid models. One of the hybrid models is the Thornes model, which requires relatively little input data, and there has been no research related to this model in Iran. Therefore, this study was conducted to determine spatial variation the soil erosion rate and sediment yield in a part of the Sanandaj Gheshlagh Dam watershed using the Thornes model utilizing GIS and remote sensing (RS).

Two hundred soil samples were collected using a stratified random sampling method and the parameters of soil texture, particle size distribution, organic carbon, and soil CaCO3 equivalent in the laboratory were measured by conventional methods. In order to determine the input parameters of the studied model, laboratory results, Landsat 8 satellite images during a 6-year period, and some monthly meteorological data including precipitation, precipitation days number and potential evapotranspiration were analyzed. Finally, using ArcMap, Saga GIS, and ENVI software, the required parameters, and maps of the models were prepared, and the studied models were run. Sediment delivery ratios (SDRs) are assumed to be a function of the travel time of surface runoff from catchment cells to the nearest downstream channel.

The results showed that the estimated average erosion of the Thornes model was 0.76 mm per year or 10.24 tons per hectare per year (assuming a bulk density of 1.4 gr/cm3), and according to the calculated SDR, the estimated sediment was calculated by the model as 4.34 tons per hectare per year. The results of the Thornes model showed that the sensitivity of this model to some parameters, including potential evapotranspiration and potential water storage capacity, was very high. Small changes in these parameters caused a significant difference in the results, which would reduce the efficiency of the model.

According to the field observations and the investigation of erosion and sedimentation situations in the studied watershed, as well as long-term information about sediment discharged from the hydrometric station (3.10 tons per hectare per year), it seems that the Thornes model has been a relatively reasonable estimate of erosion in many parts of the studied watershed. Although, the type of model used to estimate the sediment delivery ratio and then the sediment yield can have a significant effect on the model's efficiency. Considering that this model requires relatively few data, it may be possible to use it to predict erosion in watersheds with no information or with poor information.

Zinc, copper and nickel are classified as micronutrients in plant nutrition and as trace elements in environmental chemistry. These elements are essential for plants and organisms, but they cause toxicity in high concentrations. The main mechanisms of entering these elements into the food chain is the soil-plant pathway. Trace elements are present in soil in different forms with different solubility. Determining the fractions of these elements reveals more precise information about their status, and the probability of their deficiency or toxicity in long period, and in the case of changing environmental conditions. Fractionation sequence is a procedure for determining different forms of elements.

The present study was conducted on 13 calcareous soil samples around Yasuj. The samples were selected from virgin and agricultural fields without pervious application of trace elements fertilizers, and were not contaminated trace elements. Different forms of zinc (Zn), copper (Cu) and nickel (Ni) were successively extracted with F1) distilled water (soluble), F2) neutral one molar ammonium acetate (Exchangeable|), F3) one molar ammonium acetate with pH 5 (Carbonatic); F4) 0.04 molar hydroxylamine hydrochloride (NH2OH.HCl) in 25% v/v of acetic acid with a pH of 3 (FeMn-oxid associated); F5) 30% hydrogen peroxide (pH 2) with 5 ml of 0.3 M NH4OAc ammonium acetate in 20% by volume of nitric acid (OM associated); and F6) 7 M nitric acid (Residual) in duplicate and were measured with atomic absorption spectroscopy.

Water extractable zinc, copper and nickel; and neutral NH4OAc extractable copper and nickel were not detectable in the studied soil samples. Neutral NH4OAc extractable zinc was detected in 5 soil samples. The abundance of zinc, copper and nickel chemical forms were as follows: Zn- NH4OAc pH 7< NH4OAc pH 5 Zn< H2O2 Zn< NH2OH.HCl- Zn< HNO3- Zn; H2O2 Cu

The present study showed that the amount of trace elements is generally less than 100 mg/kg and most of these elements exist in residual or stable form. An increase of calcium carbonate can be associated with a decrease in the total amount of these elements and cause their deficiency.

Industrial development and human activities intensify the propagation of various contaminants in the environment. Heavy metals from various sources, such as industrial and agricultural activities, cause serious environmental hazards for the ecosystem. Environmental dusts are sometimes manmade, due to the activity of industries and human units, known as industrial dusts. The purpose of this study was to investigate the effect of industrial dust emitted from the Bauxite crasher located in the upstream of Jajarm Alumina Factory on the level of soil pollution. The study is focused on two heavy metals: Arsenic (As) and Nickel (Ni).

In this research, with regard to the wind roses of the area, first the direction of the dominant and erosive winds was determined. Then, two transects were considered: a transect in the direction of erosive wind (transect A) with 3 km length, and a transect in the direction of the dominant wind (transect B) with 5 km length. Samples from the soil surface (at a depth of 0-2 cm) were taken on these transects at regular intervals from the source of dust, i.e. Bauxite crusher. In total, 46 soil samples were collected. The concentration of Arsenic and Nickel in the soil samples was determined by the method of Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES), after acid digestion by chemical means in the laboratory. Finally, the indicators of land accumulation, pollution, comprehensive pollution and enrichment were used to determine the contamination level. Significance of increase in Arsenic and Nickel concentrations, as well as the other contamination coefficients were analyzed in SPSS software using ANOVA and T-test.

The Earth's accumulation index in the direction of erosive wind for Arsenic, at a distance of 200 to 250 m from the source, showed a medium to severe contamination. For nickel, from the source of dust production to 350 m distance, the area was identified unpolluted to medium contaminated. For Arsenic, in the dominant wind direction at a distance of 150 m and 250 to 450 m, moderate to severe pollution was determined. For Nickel, up to 900 m from the source of dusts, the area was identified unpolluted to medium contaminated.For Arsenic and Nickel, The pollution index in the direction of erosive wind up to 450 meters from the source of dust production shows a high to medium pollution level. And show medium and low to end transect, for Arsenic and Nickel. By this indicator, the high pollution levels in the dominant wind direction were determined for Arsenic up to 1200 m from the source of dusts, and medium pollution levels of the index of pollution was determined for Nickel, from the source of dust production up to 500 m far apart. And show medium and low to end transect, for Arsenic and Nickel. Comprehensive index of pollution in the case of erosive and prevailing winds for Arsenic and Nickel showed high and medium pollution levels, respectively. Enrichment factor in the direction of erosive wind indicated medium concentration of Arsenic at 350 and 400 m from Bauxite crusher, and a low enrichment for Nickel at all points. In the dominant wind direction, a medium enrichment factor for Arsenic was observed up to 250 m from bauxite crusher, while the level of Nickel enrichment at all locations was low. Finally, the statistical analysis justified the significance of the measured concentrations of Arsenic and Nickel, as well as the other coefficients of pollution level in the direction of prevailing and erosive winds.

The study of the climatic condition of Iran shows that arid and semi-arid areas are often scattered in the central areas of Iran, and salinity in these areas is one of the limiting factors for crop production. Fenugreek is a genus of Fabaceae family and one of the important products of semi-arid regions. This medicinal plant is used in the treatment of a wide range of diseases such as diabetes. Fenugreek seeds and its leaves are rich in minerals, protein and carbohydrates. The expansion of fenugreek cultivation in the world has caused this plant to face abiotic environmental stresses during the growing season. Silica plays a role in reducing the amount of sweating and preventing the side paths of sweating. Therefore, this research was conducted with the aim of evaluating the effect of silica fertilizer in increasing salinity tolerance of fenugreek plants.

The present study was conducted in order to investigate the effect of silica fertilizer on some morphological and physiological characteristics of edible and medicinal fenugreek plant in the fall of 2022 in Behbahan city in the form of pots in the form of a completely randomized design with three replications in the open air. The treatments included salt stress at three levels (0, 75 and 150 mM sodium chloride) and silica fertilizer at two levels (0 and 3 g/l) and a total of 18 pots. Fenugreek seeds are obtained from a reputable seed store (Rahimi vegetable seed store in Behbahan city). Fenugreek seeds were planted in small plastic pots with a height of 7 cm and a diameter of 8 cm filled with garden soil, leaf soil and perlite (ratio 1:1:1) so that finally there were five plants in each pot.

The results showed that in the fenugreek plant, the maximum root length (6.95 cm) and the dry weight of the aerial parts (0.046 g) in the treatment without salt stress (control) and without the use of silica fertilizer and the lowest root length (2.63 cm) ) and the dry weight of aerial organs (0.03 g) was observed in the treatment of 150 mM salinity stress and without the use of silica fertilizer. Also, the decrease in chlorophyll fluorescence (Fv/Fm ratio) in response to salinity stress was lower than the decrease observed in salinity stress without using silica fertilizer. In the salinity stress of 150 mM and the use of silica fertilizer 3 g/liter, the amount of chlorophyll fluorescence (Fv/Fm ratio) was 0.09 more than in the treatment of salinity stress of 150 mM and no silica fertilizer. The highest value of greenness index (SPAD) was obtained in the condition without salinity stress (11.60) and the lowest value was obtained in the salinity stress of 150 mM (2.30), which was significant at the five percent level. Stress causes disturbances in the path of electron transfer and destruction of tissues related to photosynthesis, and in this way, it prevents the optimal energy consumption of the plant. In this study, silica treatment reduced the negative effects of severe salinity on root length, wet and dry weight of shoot and chlorophyll fluorescence, and reduced the harmful effects of salinity on fenugreek plants.

In this experiment, it was observed that the application of silica fertilizer in severe salinity stress significantly reduced the amount of chlorophyll fluorescence in comparison with its non-application. The present study showed that adding silicone fertilizers to saline soils reduces the negative effects of salinity stress in fenugreek plants.

Barley (Hordeum vulgare L.) is one of the crops that has a high nutritional value and can be used as animal feed and cover crop to increase soil fertility, as well as has various applications in the food industry. One of the cheap and accessible methods for farmers to increase the efficiency of food elements is to use of efficient crop cultivars. Based on the principles of sustainable agriculture, one of the methods to improve the nutrition of crops is to use of biological fertilizers. Considering the importance of barley cultivation in Lorestan province, this study was conducted in order to investigate the effect of biological fertilizer and compare common cultivars in this region.

In order to investigate the growth response of some barley cultivars to biofertilizer, an experiment was conducted in the form of split plots in the form of a randomized complete block design with three replications in 2014-2016. The main plot includes three varieties of barley including Mahor (M), Izeh (I) and Khorram (K). The sub-plot of four types of biofertilizer treatments included control (without biofertilizer), Azotobacter (A), mycorrhizal (M) and Azotobacter + mycorrhizal (AM). Barley seeds were inoculated with biofertilizers according to their instructions before planting. The seeds were poured on nylon in the shade, and one package of biological fertilizer per hectare was dissolved in an appropriate volume of chlorine-free water, and after filtering the fertilizer solution with a thin cloth, it was sprayed on the seeds with a sprayer and mixed well. All of them should be evenly coated with fertilizer. At the time of plant harvesting, some growth characteristics including seed yield, straw yield, number of seeds per spike, number of spikes per square meter and weight of 1000 seeds per plot were measured.

The result of analysis of variance showed that cultivar has a significant effect on grain yield, straw yield, number of seeds per spike, number of spikes per square meter, and thousand grain weight. The result of the average comparison showed that the highest grain yield, straw yield, number of seeds per cluster, number of clusters per square meter and weight of 1000 seeds are related to M-AM treatment. As a result, Mahor variety had the highest grain yield compared to other two varieties. Among the fertilizers used, Azotobacter + Mycorrhiza was the most effective. Therefore, the interaction effect of these two treatments has the greatest effect on grain yield (4931 kg/ha), straw yield (8797 kg/ha), number of seeds per spike (16), number of spikes per square meter (546) and weight of 1000 seeds (17.8 grams).

results showed that in order to achieve the highest seed yield, it is suggested to cultivate Mahor cultivar along with Azotobacter and Mycorrhiza treatment in the region. It is necessary to evaluate other cultivars and other biofertilizers in the region.