salar rezapour

The contamination of agricultural lands, especially orchard soils with heavy metals, caused by long-term agricultural practices (overuse of fertilizers and pesticides), has become a high-priority topic for soil, food, and human health. This research was conducted with the aim of investigating the pollution and ecological risk of heavy metals in different types of soil in the apple orchards of Urmia Plain. The studied soils were classified in the Incepitsols order and the subgroups: Typic Haploxerepts (TH), Typic Endoaquepts (TE), Typic Calcixerepts (TC), Fluventic Haploxerepts (FH) and Aquic Calcixerepts (AC). The Nemerow Pollution Index (PIN) and Ecological Risk (ER) were calculated. Most heavy metals had the highest concentration in the Ap horizon. The results showed that the concentration of all studied heavy metals are lower than the permissible limit of pollution. The highest average concentration of the Zn and Cu were in the TH soil (73.1 and 21.87 mg kg-1, respectively). The difference of the concentration of Pb was significant only in the FH and there was no significant difference in other soil types. The highest average concentration of the Ni and Cd was observed in the TH soil (30.86 and 1.19 mg kg-1, respectively) and the lowest in the TE soil (25.96 and 0.8 mg kg-1, respectively). The PIN order of the studied heavy metals was as Cd>Zn>Pb>Cu>Ni, showed that the risk of Cd for the soil contamination was higher than other metals. Multivariate analysis showed that the main sources of Mn and Cu are from natural processes, while Cd, Pb and Ni were derived from the both natural and anthropogenic factors.

Evaluating and determining the minimum data set to evaluate soil quality is very important, valuable in terms of cost, and time save. The aims of this study were to assess the quality index of soils under successive, and long-term cultivation of wheat by a valid model (Integrated quality index= IQI), determine the minimum data set to evaluate the quality of soils in this region, and evaluate the relationship between soil quality index and wheat yield components. For these purposes, 18 physical, chemical, and fertility properties of the surface soil belonging to 40 soil profiles were determined in the croplands from Piranshahr region of West Azerbaijan province. The soils were classified in the three order of Mollisols, Inceptisols, and Vertisols. Total variables affecting soil quality (TDS) were determined, and minimum effective data (MDS) were estimated using principal component analysis (PCA). The soil quality index was divided into five classes according to the growth of the plant using the interpolation technique. Based on the results of PCA, five properties of organic carbon, clay, sodium adsorption ratio, calcium carbonate equivalent and silt had a specific value greater than one and were selected as MDS indicators. The highest values of IQITDS, and IQIMDS were observed in the Inceptisols, followed by Mollisols and Vertisols, respectively. A significant relationship (p <0.05) was found between wheat yield components (grain yield, and biological yield of wheat) with IQITDS and IQIMDS models, which showed a positive, and significant effect of soil quality index on wheat yield components. Moreover, the IQITDS model was more accurate than the IQIMDS model in predicting the performance of wheat components due to its higher R2. However, due to the positive, and significant correlation between IQITDS and IQIMDS (R2 =0.9(, the IQIMDS model is an economic and better model for evaluating the quality of soils in the region.

One of the important issues in the sustainable management of soils in order to optimize the agricultural production and preserve natural resources is the assessment of soil quality.  Soil quality is the capacity of a specific kind of soil to function to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation. It is also considered one of the most important factors investigated in the assessment of soil management. Knowledge of quality changes is necessary for sustainable soil management. Since soil quality cannot be measured directly, it must be obtained from the relevant characteristics. Soil quality characteristics are sets of measurable soil characteristics that are sensitive to land use change, management, or conservation operations. Using soil quality indicators is a useful tool to determine and compare soil quality. The purpose of this research is to quantify the soil quality index using multivariate analysis in different soil types in Urmia Plain.

In this research, according to the semi-detailed soil studies of Urmia plain, 24 soil profiles from different soil units of this area, which are mostly under garden and agricultural use, were excavated, described, sampled, and classified, and 96 samples were also collected from soil solum. 2 profiles in Typic Haploxerepts (TH1) soil type, 4 profiles in Fluvaquentic Endoaquepts (FE) soil type, 6 profiles in Typic Calcixerepts (TC) soil type, 2 profiles in Typic Endoaquepts (TE) soil type, 5 profiles in Fluventic soil type Haploxerepts (FH) and 2 profiles were located in Typic Halaquept (TH2) soil type. At a certain distance from the excavation site of the profiles, four soil samples were taken from four directions of the profile. Using principal component analysis (PCA), among 22 characteristics affecting soil quality (TDS), the minimum characteristics affecting soil quality (MDS) were determined. Then the soil quality in different soil types of region was evaluated using two cumulative soil quality indices (IQI) and Nemuro Quality Index (NQI) and each of them was evaluated in two sets of TDS and MDS in different soil types.

Among the measured parameters, pH had the lowest (2.5%) and salinity (EC) had the highest coefficient of variation (154.6%) in the region. Among the 22 measured soil properties, sodium absorption ratio (SAR) in the first component, nickel element (Ni) in the second component, cation exchange capacity (CEC) in the third component, sand percentage in the fourth component, active lime (ACCE) in the fifth component and absorbable phosphorus (PAW) in the sixth component were selected as MDS. The examination of the soil quality index showed that the soils of this region mainly have quality grade II (57%). The highest average value of selected soil quality index related to MDS mode in IQI model was calculated with a value of 0.79 in Fluventic Haploxerepts soil type and the lowest average value related to TDS mode in NQI model was calculated with 0.28 value in Typic Halaquepts soil type. The correlation coefficient between the soil quality index with the total category and minimum data in both IQI and NQI models was equal (R2=0.48).

The sequence order of both soil quality indices (IQIa, NQI) in both TDS and MDS conditions in the types of the studied area was as FE>TE>TH1>TC>FH>TH2. Therefore, the highest soil quality was observed in the Fluventic Endoaquepts type and the lowest soil quality was observed in the Typic Halaquepts type. Based on the results, both indicators were classified in three classes (good, medium and poor) in TDS and MDS sets. In the case of TDS, 57.83% of land (equivalent to 19731 hectares) had good class (II), 30.48% of land (equivalent to 10400 hectares) had medium class (III) and 11.69% of land (equivalent to 3990 hectares) they had poor class (IV); (very good (I) and very poor (V) class were not observed). In MDS mode, 18.56% of lands (equivalent to 6333 hectares) had very good class (I), 27.15% of lands (equivalent to 9264 hectares) had good class (II) and 54.29% of lands (equivalent to 18524 hectares) They had medium class (III); (weak class (IV) and very weak (V) were not observed). The degrees of IQIa and NQI indices were similar and were divided into three classes (good, medium and poor). As a result, 39.3% of land (equivalent to 13412 hectares) was in good class (II), 24.59% of land (equivalent to 8392 hectares) was in medium class (III) and 1.36% of land (equivalent to 12317 hectares) was placed in poor class (IV); (very good (I) and very poor (V) classes were not observed). In general, the soils of the region were limited in terms of the studied indicators in the parts leading to the lake, and there was a significant correlation between IQITDS and IQIMDS, and between NQITDS and NQIMDS. This shows that the determined MDS set can be a good representative of TDS in soil quality assessment in Urmia Plain.

Soil entities depends on its physical, chemical, and biological characteristics. Soil organic carbon (SOC) stocks is one of the main factors whose variations affect all these parameters. So, this study was performed for mapping the coefficient of variations (CV) of SOC stocks in some parts of the Simineh Roud watershed. Soil sampling performed using the Latin Hypercube method (cLHm) at 210 points from 0 to 30 cm of the soil surface, and the organic carbon was measured, then SOC stocks was calculated. In the next step, using Random Forest (RF) model the effective parameters were calculated (in this step, to model the SOC stocks, standardized spectral reflectance index and extracted data from digital elevation model were used). Finally, RF model was performed 100 times, as well as mapping of the values of upper (95th %), lower (5th %), and average SOC stocks for each pixel with a spatial resolution of 30 × 30 m was obtained. To obtain the CV with a confidence coefficient of 90%, the percentile of 95% and 5% were subtracted. The CV was obtained by dividing it by the mean. The results showed that the accuracy coefficient (R2) for modeling SOC stocks by the RF model was 0.81 and the mean accuracy coefficients including RMSE and MAE were 0.44 and 0.34 (kg/m2), respectively. Also, the results of CV mapping for the amount of SOC stocks in the study area showed that the amount of variation of this parameter varies between 3.9- 55%. Based on the results of the CV mapping of the study area, the most and lowest variations were observed in dry farming and grasslands, respectively. Probably, continuous cultivation and low return of organic matter in dry farming have increased the CV of SOC stocks in dry farming use.

In the current study, the effect of organic (vermicompost and biochar) and chemical (gypsum and elemental sulfur) amendments and combination of vermicompost and chemical treatments on the possibility of improving a saline-sodic soil was investigated. The experiment was conducted using a completely randomized design with three replications in a greenhouse condition. After mixing with different treatments, soil samples were kept in the field capacity for 120 days and then some of the most important chemical and nutritional properties of the soils were determined. The results showed that vermicompost caused a significant decrease in soil pH compared to the control treatment and its combination with elemental sulfur was the most effective treatment in improving pH (a drop of 0.75 to 0.95 unit in soil pH). All treatments significantly increased soil EC and SAR compared to the control treatment by increasing the concentration of soluble salts (such as Ca+2 and Mg+2) and replacing some of these ions with soil exchangeable Na. Among the treatments, vermicompost and gypsum had the greatest impact on EC and SAR by an increase of 2.8 to 3.8 dS m-1 in EC and 8.6 to 9.3 units in SAR. While available P, Fe, and Zn significantly increased by the direct release of nutrients from organic compounds and the improvement of soil chemical conditions following using the combination of organic (vermicompost) and chemical treatments, the individual chemical treatments had little effect on the improvement of elements. Overall, the combined application of chemical and organic treatments (vermicompost) more effectively than individual treatments has improved the unfavorable chemical conditions of saline-sodic soil and increased its fertility.

Nowadays, the heavy metal pollution caused by the landfill leachate becomes very serious because of their potential to impact on human health through the food chain. In this study, the effect of landfill leachate on the accumulation and selected indices of soil pollution to heavy metals (Zn, Cu, Cd, Pb, Ni, Mn) including contamination factor (CF), modified degree of contamination (mCd), and modified pollution index (MPI) were investigated in four different soil sites. Results indicated that soils were significantly enriched by the metals in the sequence of Zn> Cd> Ni> Cd> Cu> Mn. However, only the Cd contents exceeded the standard levels based on national and international references. Considering CF, Cd and Zn showed a high pollution class (3≤ CF< 6) in the majority of soil sites and other metals (Cu, Pb, Ni, and Mn) categorized as moderate pollution (1≤ CF< 3). Except site 1, the values of MPI were found to be moderate contamination (3<MPI <5) in the examined soils and its highest value observed in site 2.  The mean mCd content, appeared the moderate pollution class (2≤ mCd< 4), were in order of P2> P3 > P4> P1 in different soil site under the influence of leachate probably due to the quantity and quality of the leachate. Overall, the finding of the study can provide a valuable benchmark for the design of appropriate strategies and management of those agroecosystems by both local and national managers.

Over the past decades, due to climate change and water scarcity, the recovery and use of urban wastewater, especially in arid and semi-arid climates, has increased. But since wastewater is considered as an unconventional source of water, its use in agriculture requires special management which, while benefiting from it, does not have environmental and health hazards in soil, plant and surface water and underground water resources. On the other hand, sewage systems often have significant amounts of heavy and toxic metals, the type and amount of which varies from place to place, and even in the specific location, over time. The soil also has a limited capacity to absorb and maintain these elements, and if their concentration exceeds the permitted range, they can cause pollution of the water, soil, plant and human cycle. Therefore, the present study was conducted to investigate the effect of irrigation with treated wastewater in Urmia city on concentrations, distribution and contamination of Zn, Cu, Cd, Pb and Ni elements.

In field work, 6 soil profiles (5 profiles from the wastewater-irrigated soils and a profile from the well-irrigated soil as control soil) were dug, described, and sampled. At around each profile, composite soil samples were also obtained in the root depth of the area (Ap horizon, the depth of 30 cm). Soil samples were first air-dried and passed through a 2-mm sieve and then analyzed for the determination of heavy metals. The available and total fraction of zinc (Zn), copper (Cu), cadmium (Cd), leads (Pb), and nickel (Ni) were extracted by DTPA method and concentrated acid (HNO3) procedure, respectively. The content of Zn, Cu, Cd, Pb and Ni were determined by an atomic absorption spectrophotometer (Shimadzu AA-6300). Descriptive statistics were conducted using SPSS 16 for Windows. In order to study the effect of irrigation with treated wastewater on the extent of contamination of heavy metals, the AP (availability percentage), PI (Single-factor pollution index), NPI (Nemerows pollution index), and PLI (Pollution load index) in the affected soils with this wastewater was calculated. Also, all soil and water experiments were performed in 3 replicates and then, using the excel data software category, tables and charts were plotted.

The soils were alkaline and calcareous as characterized by high pH, ranging from 7.6 to 8, and calcium carbonate equivalent, ranging from 30 to 42%. On average, the value of the available fraction of the examined metals in the wastewater-irrigated soils ranged from 1.9 to 3.5 mg kg-1for Zn, 2.5- to 3.5 mg kg-1for Cu, 0.4 to 0.62 mg kg-1for Cd, 2 to 2.9 mg kg-1for Pb, and 1.34 to 1.75 mg kg-1for Ni. Comparing to the control, irrigation with wastewater resulted in a considerable build-up in the available fraction of the metals in the rank of Ni (79-142%)> Cd (54-125%)> Zn (35-73%)> Cu (13-87%)>Pb (6-32%). These patterns can be due to the quality and quantity of the used wastewater and impact of the used wastewater with its receiving soils. Similar to the available fraction, there was an increasing trend in the total fraction of metals in the order of Cd> Zn>Pb> Ni> Cu following wastewater irrigation. In this context, the mean content of total Zn, Cu, Cd, Pb, and Ni in wastewater-irrigated soils was as 51-157%, 10-32%, 243-310, 11-203%, and 13-126% higher than those of control soil, respectively. In spite of such enrichment, only the Cd values exceeded the maximum acceptable limits. The AP index is an appropriate index to compare the mobility potential and the toxicity of heavy metals in soil. In this study, the highest rate of this index among the heavy metals was related to Cd and its lowest level was related to Pb, which showed more toxicity and more mobility of Cd compared with other elements. The average of single-factor pollution index of five elements was observed in sequence Cd> Zn> Ni>Pb> Cu that the element of Cd had the highest class of PI (class 4). The highest and lowest of NPI values of five elements were observed in profiles 4 and 2, respectively. Also, the greatest effect of the five elements of this study is on the elements of Cd and Zn in the generation of this level of contamination. The pollution index of the five studied elements in irrigated soils with treated wastewater was similar to the NPI, its maximum was observed in profile 4 and Cd showed the highest effect on increasing the value of this index.

The results of this study showed that irrigation with sewage significantly increased the available fraction of the metals in the order of Ni (78.9-141.8%)> Cd (54.4-125%)> Zn (35.7-73.3%>Cu (13-87%)>Pb (6-32.3%) compared to the control. However, with the exception of cadmium, the available fraction of other elements was within the permissible limit. Compared to the control, in the majority of studied soils, the total fraction of the metals (with the exception of copper) was significantly increased and the lowest and highest increase associated with Cu (10-32%) and Cd (2 - 3 times). Also, the results of pollutant indices showed that the majority of the studied soils were in the low to high contamination and Cd was known as the major metal affecting the indices yield.

Human activities such as intensive cultivation and land use changes alter nutrients fluxes (mainly iron) and mineralogy in soil and terrestrial ecosystems. Iron is an essential element for plants and microorganisms and its solubility is controlled by stable hydroxides, oxyhydroxides, and oxides. In general, parent material, climate, and landscape position are the major factors that accelerate the weathering of the minerals and rocks containing Fe in the regional scale. However, long-term cultivation and intensified agriculture may be the dominant attributes of modifications in soil properties like Fe compounds mainly in arid and semiarid regions, where the irrigational and agricultural practice is current over long-term periods. Although substantial data is documented on Vertisols properties, few studies are available to assess the effects of long-term continuous cultivation on the characteristic and distribution of iron oxides and their mineralogy, mainly in calcareous environments.
This study was conducted in the Piranshahr - Pasvah area (36° 46 to 36° 50 N and 45° 09 to 45° 50 E, 1500 m above sea level), West Azarbaijan Province, northwest of Iran. Six soil profiles belonging to three subgroups of Vertisols order (Chromic Calcixererts, Typic Haploxererts, and Typic Calcixererts) were described and sampled from the cultivated soils and similar soils from the nearby uncultivated region as grassland. Soil samples were air-dried and passed through a 2-mm mesh sieve before the analysis. Soil analysis included particle-size distribution, pH and electrical conductivity (EC), soil organic carbon (SOC), calcium carbonate equivalent (CCE), cation exchange capacity (CEC), the determination of iron oxides forms and mineralogical composition. Free or pedogenic Fe oxides (Fed) including crystalline, poorly crystalline, and organically bound Fe were extracted by dithionite–citrate–bicarbonate (DCB) method. Poorly crystalline and organically bound Fe (Feo) were extracted using 0.2 M ammonium oxalate (AO). Organic complex of Fe (Fep) was extracted by 0.1 M Na-pyrophosphate at pH 10. All Fe oxide forms were determined using atomic absorption spectrometry. The difference between DCB-Fe and AO-Fe was considered as an estimation of crystalline Fe oxides form.
The results showed that long-term cropping caused a considerable drop in organic carbon and calcium carbonates along with a noticeable rise in the values of clay and cation exchange capacity as a result of accelerated alteration by farming activities and interactions between the used irrigation water and soils receiving it. Long-term cultivation improved the amount of Fed and Fecry (crystalline Fe) from 1 to 64% and 44 to 90%, respectively, than those of uncultivated soils which can be explained in some pathways: (1) accelerated weathering of Fe-bearing minerals (such as biotite, chlorite, feldspars, amphibole, and pyroxene) in the cultivated soils and (2) the higher temperature condition and the more number of wetting–drying cycles in the cultivated soils compared to the uncultivated soils. Despite the fact that long-term cultivation caused a significant decrease in organic matter, a pronounced increase in organic complex of Fe with the range of 19 to 61% was recorded with farming practices. Such pattern can be contributed to the chemistry of organic matter and the presence of more stable fraction (passive fraction) of soil organic matter in the cultivated soils. The XRD patterns of primary Fe-bearing minerals (such as amphibole, pyroxene, and feldspar) had less intense in the cultivated soils compared to those of the adjacent uncultivated soils, indicating that probably cultivation promoted the instability and weatherability of Fe-bearing minerals as well as the loss of Fe from the minerals. In contrast, the X-ray reflections of secondary Fe-oxide minerals such goethite appeared to be higher, sharper and intense by long-term cropping, suggesting that agricultural practices also promoted the crystallization of the soil Fe oxides. Compared to the uncultivated soils, long-term agricultural practices caused some changes in X-ray reflections of chlorite, illite, and smectite.
The results showed that the weathering of Fe-bearing minerals and layer silicates, as well as the production of Fe oxide forms were promoted under long-term continuous cropping. Under cultivation, a pronounced increase in Fe-oxide forms, particularly Fed and Fecry, was recorded for the most of the examined soils which can be associated with the combined effects of increased soil temperature and moisture content from irrigation and farming practices. As emphasized, the combined effects of increased compounds from agricultural input (such as chemical and organic fertilizers, the compound of irrigation water, and moldboard tillage) as well as increased precipitation from irrigation interacted to create conditions for: (1) more intense the weathering of Fe-bearing minerals and (2) the more production of iron oxides forms in the cultivated soils.

Multiple biological and physiological processes in the plant, including carbohydrates and proteins formation, activation of 50 enzymes for energy transmission as well as reducing water losses from leaf pores, are mostly affected by the presence of potassium in the plant. In order to test this hypothesis, five soil subgroups (TypicCalcixerepts, FluventicHaploxerepts, TypicEndoaquepts, TypicHalaquepts and VerticEndoaquepts) belonging 15 series of gardened and adjoining virgin soils were described and sampled. The studied soils had been influenced under horticultural practices for over five decades.
The soil samples were analyzed for different K forms, K adsorption and physico- chemical properties after air drying and grinding to pass through a 2 mm-sieve. The particle-size distribution was determined by the hydrometer method (Bouyoucos, 1962). The total carbonate in the soil expressed as the calcium carbonate equivalent (CCE) was determined by a rapid titration method (Nelson, 1982). Organic matter (OM) was measuredby the Walkley and Black (1934) dichromate oxidation method. The pH of the soil was analyzed in 2:1 CaCl2/soil suspension using glass electrode pH meter (Crockford and Norwell, 1956) and EC was detected in a saturated extract. The cation exchange capacity (CEC) was measured using sodium acetate (1 M NaOAc) at pH 8.2 (Chapman, 1965). Water soluble K was extracted with deionized water (1: 5 w/v) after shaking for 30 minutes on a mechanical shaker and later contents were centrifuged to separate clear extract (Jackson 1973). Exchangeable K was determined by extracting the soil with neutral normal ammonium acetate, Non-exchangeable K was estimated as the difference between boiling 1N HNO3 –K and neutral normal ammonium acetate K (Thomas 1982).
The result showed that for most of the studied soils, long-terms horticultural practices decreased the amount of different K forms as a result of changes in soils types, agricultural practices and soil properties. In Comparing to the virgin soils, long-term horticultural and irrigation activities caused a decrease?? in soluble K from 0.05 (a drop of 15% with depletion factor of 0.85) to 1.48 mmol l-1(a drop of 95% with depletion factor of 0.05), potassium absorption ratio (PAR) from 0.08 (a drop of 31% with depletion factor of 0.69) to 1.17 mmol l-1(a drop of 97% with depletion factor of 0.03), exchangeable K from 12.01 (a drop of 3% with depletion factor of 0.97) to 285.98 mg kg-1 (a drop of 97% with depletion factor of 0.43),exchangeable potassium percentage(EPP) from 0.49 (a drop of 12% with depletion factor of 0.88) to 3.47% (a drop of 59% with depletion factor of 0.41), available K from10.42 (a drop of 3% with depletion factor of 0.97) to 180.65 mg kg-1(a drop of 53% with depletion factor of 0.47) and non-exchangeable potassium from 43.05 (a drop of 8% with depletion factor of 0.92) to 114.65 mg kg-1 (a drop of 19% with depletion factor of 0.81). Isotherm studies showed that the uptake of potassium in gardened series were more than virgin soils. The highest adsorption values were observed in VerticEndoaquepts (gottape) subgroup.In this series of soil, amount of available k (potassium soluble exchangeable K) and expandable clay increased by long-term horticultural practices which can be effective in increasing K buffering capacity.
long-term horticultural practices decreased K in soil solution and potassium adsorption ratio. The main reasons for the decline of soluble K can be explained by possible movement of K into the depths, dense cultivation and harvesting crops as well as high levels of calcium and magnesium in irrigation water of study area.In comparison with adjoining virgin soils, horticultural practices caused significant decrease in the amount of exchangeable K, exchangeable K percentage (EPP) and available K. The most important cause of reduced exchangeable potassium may be related toK uptake by apple trees (The study area is generally under the apple orchard user) which had the great need for K. Consequently, due to lack of fertilizers application and agricultural practices,the amount of available K declined in soils about 80percent. On the other hand, In the Non-exchangeable K amount with long-term horticultural practices non- significant reduction occurred. Since the amount of exchangeable and available k in these soils is high, it seems to be enough to satisfy the needs of the regional products.

Continuous horticultural practice may be manifesting some modifications on physico-chemical and different K forms of soil. To investigate this hypothesis, five soils subgroups (Typic Calcixerepts, Fluventic Haploxerepts, Typic Endoaquepts, Typic Halaquepts and Vertic Endoaqupts) of cultivated and adjoining uncultivated soils of south Urmia that have been under continuous horticultural practice for more than 5 decades were described and sampled. The soil samples were analyzed for different K forms and K adsorption properties after they were air-dried and ground to pass through a 2-mm sieve. The result showed that for most of the studied soils, continuous horticultural practices decreased the amount of different K forms as result of changes in soils types, agricultural practices and soil properties. Comparisons also showed that continuous horticultural practice significantly caused reduction in the all forms of K excluding the non-exchangeable K (NEK). Among the soluble K and NEK, respectively, showed the highest and the least changes. The continuous horticultural practice decreased 100 percent soluble K, 60 percent exchangeable K, 60 percent available K in the studied soil subgroups. Mineralogical studies also suggested that continuous horticultural practices caused changes in the relative intensity and position of the XRD pattern (peak) of illite and smectite.