نشریه تحقیقات کاربردی خاک
سال یازدهم شماره 4 (زمستان 1402)

Land use change is a factor that affects the loss of soil fertility such as macronutrient. Potassium (K) is an essential macro-nutrient for the growth of plant that its distribution in soil depends on clay minerals, manure, degree of weathering, land use type, climate condition and leaching.  The purpose of this research was an investigation of different K forms in three agricultures, rangeland and forest park land uses in surface (0-15 cm) and subsurface (15-30 cm) depths in Oshtorninan region (Lorestan province). Soil sampling was done in 45 points in three land use and two depths. Some soil physicochemical and different K forms were determined in laboratory. Mineralogical study was carried out with X-ray diffraction. Results showed that the mean contents of soluble (15.9 mgkg-1), non-exchangeable (627.5 mgkg-1) and structural K (3563.2 mg kg-1) in the forest park and the content of exchangeable K (484 mgkg-1) in the rangeland was higher than other land uses. All K forms (except structural K) were higher in the surface soils compared to the subsurface soils. Land use had significant effects (p < 0.01) on all K forms, but depth had no significant effect on them. Soluble K only had a positively significant correlation with exchangeable K. Positively significant correlations between structural K with exchangeable and non-exchangeable K were observed. Also, clay and cation exchange capacity had positively significant relationships with exchangeable, non-exchangeable and structural K. Mineralogical studies showed that vermiculite and smectite control the content of exchangeable K in the rangeland and the smectite and illite are important minerals that control the non-exchangeable and structural K in the forest park. The change in land use from rangeland to agricultural land may induces the long-term reduction of all K forms, while the change to forest park increases soluble, non-exchangeable and structural K forms.

The aim of this study was to evaluate the nutritional status of dryland wheat using diagnosis, and recommendation integrated system (DRIS) method. To determine the DRIS indices, and norms in dryland wheat, 54 samples were collected from shoots, and concentrations of nutrients nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) were determined. To determine the norms, the farms were divided into two groups of high and low-yielding farms based on yield. Optimum concentrations of nutrients for macronutrients N, P, and K were 0.87- 1.35, 0.0360 - 0.104, 2.18 - 1.02 (%), and for micronutrients including Fe, Mn, Cu, and Zn were 170-430, 29-51, 3.6 – 8.4, 13 – 27 (mg kg-1), respectively, as well as optimum nutrient concentrations for N, P, and K were 1.11, 0.07 and 1.6 (%), and for Fe, Mn, Cu, and Zn 300, 40, 6, and 20 (mg kg-1) respectively, were determined. In most low-yielding farms, the nutritional balance index (NBI) was much higher than zero, indicating more nutrient imbalance in these farms. The overall priority for macro and micronutrients is P > K > Fe > N > Mn > Zn > Cu, which should be paid attention to P, K, Fe, and N in the nutritional program.

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.

Microbial inoculation is effective in improving plant growth and tolerance to environmental stresses, and green refinement of contaminated soils with heavy metals. This study was carried out in order to evaluate the effect of Piriformospora indica inoculation on phytoremediation of lead by tall fescue (Festuca arundinacea cv. Tomahawk) at different levels of Pb contamination. It was performed in pot experiment as factorial based on randomized complete block design with three replications which the experimental factors included inoculation, and non-inoculation with P. indica, and Pb contamination (0, 500, and 800 mg kg-1 of soil). Pb contamination at levels of 500 and 800 mg kg-1 of soil caused a decrease of 31.46% and 43.98% of shoot dry weight, 31.2% and 44.32% of relative yield, 10.89%, and 15.74% of leaf relative water content, 47.8%, and 47.55% of chlorophyll a, 47.41%, and 50.22% of chlorophyll b, 5.22%, and 11.64% of root phosphorus content, 11.44%, and 14.47% leaf nitrogen content, and increase of 27.49% and 20.89% of leaf proline and 6.13% and 14.71% of leaf soluble sugars respectively. P. indica inoculation in compared with non- inoculation in Pb contamination at both 500 and 800 mg kg-1 of soil by increasing the accumulation of 26.34% and 18.67% Pb in roots as well as increasing the 64.13% and 59.83% root metal extraction caused an increase of 40.22% and 18.12% of root fresh and 51.22% and 50.59% dry weight, 44.32% and 40.72% of chlorophyll a and 16.98% and 33.95% of chlorophyll b content, 15.71% and 17.6% of root phosphorus concentration and 16.21% and 13.92% of shoot phosphorus concentration, respectively. It is inferred that microbial inoculation with P. indica increases the accumulation of Pb in the roots of Festuca arundinacea and it is suggested that P. indica-inoculated Festuca arundinacea cv. Tomahawk can be used as biologically useful approach in phytoremediation of Pb-contaminated soils.

Soil Saturated Hydraulic conductivity is one of the most important soils physical properties, which has particular importance in studying and modeling the movement of water and salts in porous media. Because these methods are expensive and time consuming. Therefore, it seems necessary to estimate saturated hydraulic conductivity using of fast, low-cost methods with acceptable accuracy. In this research, geostatistical and response surface methods were used to estimate the hydraulic conductivity of soil saturation, the data was prepared from 135 soil profiles related to soil science and land reform studies of Ardabil Agricultural Jihad Organization in Fatah Ali Plain area. The main factor included saturated hydraulic conductivity, soil texture, bulk density, porosity, degree of saturation, and field capacity were considered as secondary factors. Among the geostatistical methods, ordinary cokriging had the best fit and the best fitted variogram in this method was the exponential model with zero nugget effect and 156 of sill range. That showed the strength of the spatial structure of the region and the full impact of the spatial structure on region variogram.  In the ordinary cokriging method, the estimation accuracy was estimated with the regression coefficient (R2=0.93) and (RMSE=3.21). In the response surface model, the best saturated hydraulic conductivity model based on the effective variables, was quadratic model with regression coefficient of 0.94 and the adequacy of accuracy of 49.2 was estimated, to determine the maximum hydraulic conductivity assuming the change of other effective parameters in the range of measured values, a target with desirability of 0.67 was obtained. This goal calculated the hydraulic conductivity of the soil at 8.9 (%) clay and 86 (%) sand, equal to 57.15 (mm/hour). Therefore, both methods are highly accurate in determining the hydraulic conductivity of soil saturation, but the response surface method (RSM) was more accurate.

Heavy soil erosion and sedimentation at the watershed level can trigger intense environmental consequences. This research proposes a modeling technique to estimate changes in incremental soil erosion over time and evaluate the effect of vegetation cover on soil erosion in critical areas. For this, the study employed the Water World Policy Support System (WWPSS) for simultaneous modeling of changes in vegetation cover and soil erosion. Changes in vegetation cover from 2000 to 2020 were studied by extracting data from the model databases received from MODIS VCF satellite images. The study further used maps and calculations of the run model to measure the amount of net soil erosion (erosion minus sedimentation in the same place) and subsequent change in its level under two baseline (before loss of vegetation cover) and current (post-vegetation loss) situations. It was found that the average percentage of grass-pasture cover in the studied watershed has declined from 78.36% (under the baseline situation in 2000) to about 47% (under the current situation). The average amount of net soil erosion in the two sub-watersheds of Aji Chai and Marduq Chai has increased by more than 277% and 33%, respectively, signifying them to be the most vulnerable sub-watersheds (among all the four studied sub-watersheds) to soil erosion at critical areas. Overall as expected, a 40% loss of vegetation in the studied watershed has provoked adversely hazardous consequences during the studied period while cumulatively leading to over 8 million tons of soil deterioration in 15 years. The proposed method is assumed to be advantageous by providing quantitative and rapid environmental assessments that entail precise quantification of environmental consequences like soil erosion.

Iron is one of the essential nutrients for plant growth that its deficiency is considered as an important problem in calcareous soils. Therefore, this experiment was conducted to investigate the effect of different organic matters and their interactions with iron oxide powder on nutrient uptake and yield of wheat in a completely randomized design with factorial arrangement. The experimental factors were organic matter type including lemon pomace, sour grape pomace, tomato pomace, black tea pomace, spent coffee grounds, and their composts (1% by weight), and iron oxide powder on two levels (zero, and 50 mg of iron per kg of soil) as potted culture with three replications. The results showed that shoot dry weight increased significantly in all treatments except (lemon pomace and spent coffee grounds and tea pomace compost and spent coffee grounds compost) compared to the control. Also, most of the treatments caused a significant increase in the uptake of nitrogen, potassium and iron compared to the control. Tomato pomace compost, in comparison to other treatments had the greatest impact on all parameters. The uptake of nitrogen, potassium and iron, were significantly increased by adding tomato pomace compost, which the amount of these increases compared to the use of iron oxide powder alone, were 36.1, 39.7, 148.9 percent, respectively. Also, the comparison between the different pomaces and their compost, showed that the pomaces were more effective than their compost in all parameters except the dry weight of the shoot. Finally, it was found that among all of the treatments, respectively, tomato pomace compost and sour grape pomace, and for the interaction effects of organic matter with iron oxide powder, respectively, tomato and lemon pomace compost, effectively, improved different soil and plant properties, compared to the other treatments.

Soil contamination with heavy metals is an important, common environmental, public health challenge, and concern worldwide. Therefore, this study was conducted to evaluate the contamination level and health risk of potentially toxic elements (cobalt, copper, manganese and nickel) in the surface soil samples of the roadside environment of Hamedan in 2019. In so doing, 63 surface soil samples (0-15 cm) were collected along 700 m from a 9 km section of Goltepeh (G), Razan (R), and Kermanshah (K) roads. After acidic digestion of soil samples in the laboratory, the contents of elements were determined using ICP-OES. Based on the results obtained, the highest amounts of the analyzed elements (mg kg-1) were found in the samples collected from the R site (1.92, 334 and 22.2 for Co, Mn, and Ni, respectively), and for Cu with 25.0 mg kg-1 it was related to K site, which indicating the effect of traffic density on soil pollution. The calculated values of EF showed that the enrichment (pollution) of Cu, Mn and Ni in the stations with high traffic (Razan and Kermanshah roads) was greater than 1.5, indicating the effect of human inputs especially with the traffic origin, while the EF values for the Co indicated "non-contaminated or no enrichment" conditions. Also, the results of the health risk assessment showed that "ingestion" was the main route of exposure of children and adults to the non-carcinogenic risk (HQ) of soil contaminated with heavy metals. In all sampling stations, the values of cumulative non-carcinogenic risk index (HI) of the studied elements in both child, and adult groups indicated "low risk". In addition, Mn with an average of 82% had the highest share in causing non-carcinogenic risk for both children and adults. On the other hand, the carcinogenic risk (CR) of Co and Ni was negligible for both children and adults. Since the results indicating the impact of traffic activities on the contamination of roadside soil with heavy metals. Therefore, periodic monitoring of the sources of soil contamination in the roadside environment is recommended for the environmental and human health aspects.

Soil erosion in upstream areas has an important role in sediment entry to dams. Sediment accumulation result in decreases of dam service life, environmental problems, and acceleration of floods. In addition to climate, topography, vegetation cover and land management, soil erosion amount depends on soil characteristics and its erodibility.  In this research, soil erodibility factor and its special distribution was assessed by using of various pedotransfer functions including KUSLE, KEPIC and KDg in a part of Aliabad watershed of Roodbar, located at upstream of Sefidrood dam. The soil samples were collected from 0-10 cm depth and size distribution of soil primary particles, organic carbon content, and aggregates stability were measured. The KUSLE was calculated in two ways without codes of soil structure and permeability, and with respective codes, named as KUSLEi, and KUSLEf, respectively. The results showed that studied soils generally had coarse texture, and KUSLEi was estimated low to moderate in range of 0.11 to 0.040 ton h MJ-1 mm-1. The least soil erodibility factor belongs to KDg, which was significantly lower than the soil erodibility factors calculated by other pedotransfer functions. All of the calculated erodibility factors had significant negative correlation with mean weight diameter of aggregates which KUSLEi and KDg showed the most and least correlation with MWD, respectively. All of the erodibility factors had moderate spatial dependence, however KUSLEi showed strong spatial dependence. Therfore, it generally can be concluded that zoning map of KUSLEi  generated via kriging can be a suitable indicator of the studied soils erodibility.

The recession of the lake shores, including Lake Urmia (LU), and later exposure of the lake bed sediments to wind erosion, as a consequence of climate change and drought is an increasingly dangerous phenomenon in arid and semi-arid regions of the world. When salt particles remain unconsolidated, and uncovered on soil surface, they can be moved by wind easily, generating salt dust. These fine-grained salt particles cause salinization of agricultural lands, accelerate deforestation leading to health, and economic problems in lives neighboring residents.  The aims of the present research were to study Urmia Lake Playa (ULP) geomorphic surfaces in its western shores, and their vulnerability to dust generation. All lands from Urmia Lake recession from its western shores were selected. Different playa surfaces in the study area were identified and mapped using satellite images and Google Earth software. Then, boundaries of the mapped surfaces were checked by field observations. Later 130 soil samples from depth 0-5 cm of different surfaces were collected during spring to autumn 2019 and physicochemical analysis, mean weight diameter (MWD) and loose erodible material (LEM) were determined and finally geomorphic map of the study area was prepared in ARCGIS software. Based on the results from present study, seven geomorphic surfaces were identified in western part of ULP including clay flats, salt crusts, clay flats- salt crusts; sandy salt crusts, beach sands, sand sheets and fan delta. Each of these surfaces were subdivided to different map units based on the variation in vegetation cover and density, stability of surficial crusts and some other physicochemical properties. Among studied surfaces, sand sheets located in northern parts of the study area, next to Jabal Kandi village, had the highest LEM with 89.7 % equal to 53.8 ton.ha- soil. The study of the correlation between LEM and several soil physicochemical properties showed that high sand content and low calcium carbonate, MWD (which is also dependent of soil properties) and also low organic matter in soils of sand sheets have made these areas vulnerable to wind erosion and prone to dust generation.