نشریه تحقیقات کاربردی خاک
سال هشتم شماره 4 (زمستان 1399)

The excessive use of pesticides in recent years and their continuation in the future may have harmful effects on the microbial population of the soil, as an indicator of soil health and one of the main components of the environment. The purpose of this study was to investigate the effect of three mostly used insecticides (Diazinon, Chlorpyrifos and Imidacloprid) on ec-ophysiological and chemical indices of soil. The experiment was conducted as a factorial in a completely randomized design which included the pesticide factor at four levels (three insecticides plus control soil) and time factor at three levels (before, three months and six months after pesticide application). Concentrations of insecticides (0.1, 1 and 0.67) mg per kilogram of soil were used for imidacloprid, diazinon, and chlorpyrifos, respectively. Some biological and ec-ophysiological indices of the soil were measured at the beginning of the experiment, three and six months after the beginning of the experiment. The results showed that, the application effect of insecticides after three months affected the biological indices including dehydrogenase enzyme activity, metabolic quotient, basal respiration, substrate-induced respiration and also organic carbon decreased compared to the control -92.2%, -46.7%, -24.7%, 15.8% and -7.61%, respectively and urease enzymes activity, microbial biomass carbon, microbial biomass nitrogen, carbon to nitrogen ratio and soil microbial quotient increased compared to control 6.67%, 32.1%, 15.6%, 16.5% and 58.9. Also, the results showed that among the insecticides Chlorpyrifos and Diazinon had the highest and the least negative effect on the indices, respectively. The application of insecticides Diazinon, Chlorpyrifos and Imidacloprid at least in the short term, had a negative effect on soil ecophysiological indices and the most sensitive indices for determining the negative impact of insecticides on the soil microbial community were the dehydrogenase enzyme activity, metabolic quotient, substrate-induced respiration and basal respiration.

Wheat grain yield in semi-arid regions is negatively affected by water deficit resulted by low precipitation and soil and water loss caused by water erosion. Limited information is available on methods of controlling runoff in rainfed furrows. Therefore, this study was carried out to investigate the effects of different levels of wheat straw mulch on flow characteristics in a semi-arid region in west of Zanjan. Five levels of wheat straw mulch including 0, 25%, 50%, 75% and 100% of land surface cover (equal to 0.1.5, 3, 4.5 and 6 ton per hectare) were applied using the randomized complete block design at three replications in a rainfed wheat land. Totally, fifteen, 2m×5m. plots were installed in the field and flow characteristics including the starting time, velocity, shear stress, power and hydraulic radius were determined using a constant flow rate of 2 lit min-1. Based on the results, soil properties and flow characteristics were strongly affected by straw mulch level (p< 0.01). Soil properties (field capacity and infiltration rate) improved by application of straw mulch. Straw mulch also  decreased flow velocity, shear stress, hydraulic radius and runoff volume in the furrows. At the 100% wheat straw mulch level, field capacity (15.6%) and infiltration rate (12.1 cm h-1) increased 74% and 2.4 times in comparison with the control treatment. The runoff volume was 3.7 times less than the control treatment in this level of straw mulch. No significant difference was found between 75% and 100% straw mulch level in improving soil properties and controlling flow characteristics.  This study indicated that application of 75% straw mulch level equal to 4.5 ton per hectare is an effective level to improve soil properties and decrease flow velocity in wheat furrows under rainfed condition.

Investigation of the the relationship between soils and grouping them based on different factors, plays an important role in different fields and aspects such as land management and sustainable agriculture. This launched by creating subjective or mental models and using environmental factors in the format of traditional soil maps. It afterward continued by relying on distance and similarity measurement through quantitative or mathematical models. This study aims to compare soil groups in soil maps with classical and modern models. For this purpose, legacy soil data of a map of Shahrekord-Borujen in Chaharmahal-va-Bakhtiari province is classified by using various algorithms: Heretical clustering, k-means, classification tree, and taxonomic distance. Soil groups gained from these numerical methods were then compared with soil groups in the legacy maps. Results of investigations in 90m spatial resolution showed that the classes from the decision tree were more in line with the legacy soil classes. The hierarchical clustering and k-means also resulted in group compositions similar to those of the legacy maps in terms of soil environmental and morphological characteristics that follow the traditional photographic units. The taxonomic distance led to the best combination of soil classes in the term of their traits with the highest within-class correlation (0.522) and the least within-group variance to between-group variance ratio. Low p-values in multivariate analysis of variance (MANOVA) between 0.001 in the traditional model up to 0.014 in the tree model showed that the models used in this study have effectively separated soils, except for K-means. Overall, findings show that using numerical classification models can discover the quantitative relations between soils. The surveyor can afterward modify the composition of soil classes considering his experience and knowledge of the study area in order to achieve more homogenous soil groups in terms of their management and taxonomic characteristics.

Drought and the resulting stress are one of the most important and common environmental stresses which limit agricultural production. Researchers have used organic amendments such as biochar to improve soil properties and reduce the effects of the undesirable stresses. The purpose of this study was to investigate the effect of using the provided biochar of walnut wood and walnut green shell on retention curve and hydraulic parameters of a sandy soil in completely randomized design. For this purpose, the biochar were produced at 400 0C for 2 h. The amendments (walnut wood and walnut green shell and their biochar) at 1 and 2 w/w% ratios (36 and 72 t ha-1, respectively) were mixed with soil sample in three replications and were incubated for 120 days in greenhouse conditions. The retention curve of the incubated soils was measured using sandbox and pressure plates apparatus. Statistical analysis showed that the applied biochar had significant effects on bulk density, porosity, stability of aggregates in wet sieving, and van Genuchten’s parameters (except residual moisture parameter). Application of 2% walnut green shell biochar led to 17% reduction in bulk density (17%) compared to the control and increased the total soil porosity. Application of 2% biochar had the highest effect on the soil water retention curve. Also, the addition of biochar significantly increased soil water retention at low tension and decreased the difference in soil moisture content between treatments. Since water retention curve in lower tension is affected by coarse soil pores and soil structure it could be concluded that addition of biochar improved soil structure and increased coarse soil porosity. Application of appropriate biochar as an amendment in agricultural soil can partially improve the physical and hydraulic properties of sandy soils in semiarid region.

Soil erosion reduces the fertility of upstream soils and damages them by sedimentation downstream. In order to evaluate the impact of watershed mechanical operations on erosion control and sediment reduction, field surveys were performed to evaluate the performance of each structure in the Bukan Alikandi watershed. Soil erosion and sedimentation status was evaluated using MPSIAC model and sediment volumetric measurements were carried out behind mechanical structures to evaluate the effect of watershed management. Evaluation results showed that mechanical operations were able to reduce soil erosion and sedimentation percentage. Due to the construction of check dams at Alikandi watershed, a total of 75806.5 cubic meters of controlled sediment is about 42%. The volume of sediment control per unit volume was 0.21 m3 for gabion dams, 0.77 for rock check dams with cement cover and 0.43 m3 for cement check dams, respectively. Therefore, rock check dams with cement cover had the greatest impact on the basin. Finally, it is suggested that in the desired basin and basins with similar conditions, for the positive impact and better performance of executive measures, a combination of mechanical and biological be implemented in the area.

Arsenic is a carcinogenic agent, which is found in water and soil resources at concentrations above the acceptable level and considered as an environmental threat. Soil and water contamination by arsenic is the most important route of its entry into the human food chain. Arsenic has been detected in both inorganic and organic forms in the environment which compared to organic forms, inorganic compounds of arsenic (arsenate and arsenite) are more toxic due to their higher solubility and mobility. Soil solid particles, especially iron (oxy)hydroxides and minerals considered as the main sinks of arsenic in soil, which its stability and mobility depend on environmental conditions such as pH, Eh and the presence of competing ions. Arsenic detoxification techniques are categorized into three physical, chemical and biological types. The low cost, environment-friendly, lack of toxic residue production, arsenic speciation and easy operation are the important factors that influence the choice of decontamination method. In this paper, the factors that affect the concentration and speciation of arsenic in soil and water are reviewed. In the following, the methods of arsenic decontamination of soil and water with emphasis on its adsorption and immobilization methods using natural, non-polluting, abundant and high adsorption capacitance materials are reviewed.

Land suitability evaluation is the most important step in land use planning and rapid assessment of the land suitability with high precision and accuracy is necessary. Therefore, the use of computer models for management and assessment of soil resources is inevitable. The aim of this study was to use MicroLEIS system in the form of a Terraza model to identify the bioclimatic deficiency, Cervatana capability and land suitability prediction and Almagra for land suitability evaluation of olive, peach and citrus utilization types in an area of 16555 hectares in the northeast of East Azerbaijan province (Khodaafarin County). The morphological and physiochemical characteristics of 11 control profiles were studied. The studied soils were classified in two order of Aridisols and Entisols and suborder of Calcids, Cambids, Gypsids and Orthents. Based on Terraza, the olive and peach utilization types were in h2 class of deficiency of humidity and citrus was in class of h3. Thus, during the growth period, their production will be reduced between 20 to 40% and 40 to 60% respectively. The results of Cervatana showed that 82.82% of the study area was talent to agriculture and the 17.18% are recommended for pasture or forest plantation. The results of the evaluation of suitability to the Almagra also showed that none of the studied utilization types are in the S1 class. The most limiting of soil factors is the frequency and spread of soil texture, useful depth, lime, profile development and sodium saturation. Finally, the peach utilization type is the most suitable product considering the climatic and the characteristics of landscape and soil, and the priority of cultivation in the area is peach, olive and citrus.

The main objective of the current research was to evaluate the effect of Cd concentrations on the growth, uptake of P, Fe, Zn, Cu and Mn of alfalfa plant mycorrhized by Rhizophagus intraradices. A pot culture experiment was performed as completely randomized design by two factors, including AM fungus (inoculated with R. intraradices and non-inoculated) and four levels of Cd (0, 15, 30 and 45 µM Cd+2) with three replications. Shoot and root dry weights of mycorrhizal (M) and non-mycorrhizal (NM) plants were affected by increasing of Cd levels. At the levels of 15, 30 and 45 µM Cd+2 shoot and root dry weights were decreased by 0%, 8.2%, 25% and 9.5%, 16.2%, 39.8% compared to the control (0 µM Cd+2), respectively. Shoot and root dry weights of M plants were increased by 48.7% and 42.8% compared to the NM ones. P contents of shoot and root were affected by AM fungus, so that the shoot and root P contents of M plants were increased by 54.1% and 49.6% compared to the NM ones. Root colonization and mycorrhizal dependency were affected by Cd treatments. At the levels of 15 and 30 µM Cd+2, root colonization and mycorrhizal dependency were increased by 38.2%, 35.7% and 100%, 77% compared to the control, respectively. Maximum Cd contents of shoot and root were recorded at the levels of 15 and 45 µM Cd+2 in M plants which were increased by 81.97% and 71.99% respectively, compared to the NM ones at the same levels. Cd-translocation from root to shoot was decreased as the Cd concentration increased. At the all levels of Cd, the concentrations of Fe, Zn, Cu and Mn were often higher in roots than in shoots. Generally, with increasing Cd concentration, plant uptake of Fe, Zn, Cu and Mn were decreased compared to the control. At the Cd levels, metal translocation from root to shoot were decreased for Fe, Zn and Mn and increased for Cu compared to the control, respectively.

The water crisis coupling with the soil salinization have made the agricultural sector facing serious challenges. This study aims to investigate the effects of nitrogen fertilizer levels on yield and water use efficiency of autumn Canola (Brassica Napus) under drought and salinity stress conditions in Lake Urmia basin. This research has been conducted as factorial based on randomized complete blocks design with three replications at the research farm of Department of Water Engineering, Urmia University. Irrigation as first factor have been applied at three levels including 50%, 75% and 100% of field capacity, salinity stress as second factor have been applied at three levels including irrigation without salinity, with 7 and 14 dS/m saline water, and nitrogen as third factor have been applied in 60, 120 and 180 kg/hectare. The highest grain yield (4.45 tons/hectare) have been achieved in field capacity irrigation, nitrogen 180 kg/hectare without salinity stress treatments and the lowest rain yield (0.59 tons/hectare) have been achieved in up to 50% of field capacity irrigation, 60 kg/hectare pure nitrogen and 14 dS/m salinity treatments. The highest value of this index (8.5 tons/hectare) have been achieved in field capacity irrigation, nitrogen 180 kg/hectare without salinity stress treatments and the lowest rain yield (1.2 tons/hectare) have been achieved in up to 50% of field capacity irrigation, 60 kg/hectare pure nitrogen and 14 dS/m salinity treatments According to the results, the use of nitrogen fertilizer lead to greatly amend the effects of salinity stress. Among the measured parameters, plant height is the most resistant trait with the least variation in stress conditions. Increasing salinity leads to reduce the water use efficiency.

Sustainable agriculture will be achieved only when land is used, essentially based on soil and water capacity. Otherwise, agricultural lands will influenced by increasing degradation and erosion. Therefore, this study aimed to evaluate the land suitability of orchard (200 hectares) located on the southern Urmia plain (Darbrud soil series) and also provide a suitable irrigation model using CROPWAT considering irrigation water shortage and lack of adequate drainage for apples as a main crop in this area (%55). Ten years of climate data was collected, and the land index was evaluated by parametric method (square root method). Limitation in drainage status resulted in (S3w) for land subclass, while for climate and temperature suitability, the minimum average temperature during the month before harvest, reduced the subclass to S2. Moreover, CROPWAT model was used to estimate the efficiency of model for important horticultural crops under a proper-irrigation management in the study area through comparing the results of the model with those from the FAO model. The result of this study indicates that an excessive or over irrigation regime has occurred in the studied fields which have no positive effect on the crop yield or economic benefits. Providing irrigation projects based on a suitable water model will increase the water use efficiency.

Phosphorus after nitrogen is the most important and essential nutrient for plants, and plays a major role in the process of energy production and transfer. In an experiment, adsorption efficiency and consumption of phosphorus in 100 oily sunflower inbred lines which collected from different parts of the world were evaluated based on a completely randomized design with three replications in potted conditions under both optimum and phosphorus deficiency states. The results of analysis of variance revealed that there is a significant difference among lines in terms of aerial part dried weight, total phosphorus content and concentration, fertilizer response, phosphorus acquisition efficiency, phosphorus utilization efficiency and calculated phosphorus efficiency. The average of fertilizer response for sunflower lines was 47.35. Totally, the index varied from 4.7 to 226.7 grams. The phosphorus acquisition efficiency index ranged from 0.08 to 0.79 with an average of 0.38. The average of phosphorus utilization efficiency in optimal conditions was 2.67 and in the case of phosphorus deficit conditions it was 1.35. The index varied from 1.11 to 6.11 grams' dry matter per milligram of phosphorus. The phosphorus efficiency index varied from 32.38 to 90.22%. Based on calculated indices, the sunflower lines including 1, 73, 2, 8, 34, 46, 47, 70 and 89 are introduced as phosphorus efficient genotypes and lines including 45, 56, 95, 11, 12, 27, 52, 71, 73, 78 and 94 introduced as phosphorus non-efficient genotypes. Phosphorous efficient lines can be potentially used in the production of phosphorus efficient sunflower hybrids in the breeding programs

Particle size distribution (PSD) is one of the most important soil physical properties. Determining soil PSD using low-cost, rapid, and accurate methods is of interest to researchers. In this research, performance of seven fractal models to estimate PSD characteristics of 40 samples in five soil textural classes, including clay, clay loam, silty clay, sandy loam, and sandy clay loam was investigated using different statistical indices. For this purpose, 28 points of the soil PSD curve were measured using either sieve or hydrometric method for each soil sample. Fitting of the PSD models was performed by nonlinear regression using the Matlab program. The results showed the effect of soil texture on the fractal dimension value. Among the models studied, Perrier et al. (1999) model had the most fitting error for all soil textures. Also, Bird et al. (2000), Perrier & Bird (2002) and Kravchenko & Zhang (1998) models had the best performance in fractal dimension estimation. The statistical indices showed that two-parameter fractal models have a better fit for the soil PSD curve than single-parameter ones. The studied PSD models were relatively accurate in estimating D60 and D50 values. The results of this study indicated that fractal models can be reasonably capable of estimating soil PSD characteristics.

Wind erosion is one of the important aspects of land degradation in arid and semi-arid regions and is a serious challenge to sustainable production and land management. In this study, a comprehensive evaluation model is developed which proves to be effective with an overall precision of 66.12% to estimate soil erosion on the eastern shore of Urmia Lake. Six critical factors including soil erodibility, aridity index, soil crustal indices, vegetation fraction, wind field intensity and snow cover days are employed to model the wind erosion. 153 soil samples randomly were collected from 0-10 cm depth points from three elevation layers (1271-1273, 1273-1275 and 1275-1278 meter above sea level) and transfer to laboratory for physical and chemical analyzing. The AHP method is applied to determine the weight of each factor in a multi-criteria system, during the years 2005–2017 and poor vegetation cover with low annual variations was identified as the most important factor affecting the wind erosion model. Results show that high, low and moderate erosion classes have 0.76, 0.64 and 0.57 overall accuracy, respectively. The reason of low accuracy of low and medium erosion classes was the lower number of field observation points of these classes. The results shows that 45.56% of the study area classified as severe wind erosion class (WEI <0.53), while 23.97% has erosion Moderate (0.48> WEI> 0.53) and 30.47% have been labeled as low erosion (0.48> WEI). Consequently, the accuracy of the overall assessment of soil erosion model developed in this study is acceptable and could be applied in the eastern part of Lake Urmia. Results shows the descending trend in erosion intensity from the middle parts to the north and south parts of the study area.

Land vegetation and soil degradation have considerable effects on greenhouse gas emissions resulting in global warming. Hence, this study aims to investigate the relationsip between soil organic carbon storage (SOCS) and different vegetation cover/ land uses in two soil depths (0-20 and 20-40 cm) in the Bajestan, Khorasan Razavi, Iran. A total of 122 soil samples (two depths× 61 soil sampling sites= 122 soil samples) were collected including orchard (pomegranate, pistachio and saffron), farmland (barley), desert (under and between haloxylon shrubs), and pasture. Results showed that surface layer of desert lands covered by haloxylon shrubs (3.17 Kg m-2) and both soil depths in pomegranate orchards (2.57 kg m-2 in 0-20 cm and 1.63 kg m-2 in 20-40 cm) had the highest SOCS content. Furthermore, it was found that soils under haloxylon shrubs accounted for 21.35% of surface SOCS as well as for 116.66 tons ha-1of absorbed CO2 in the soil and about 3.5 times more than areas located between haloxylon shrubs. Finally, the economic value of CO2 absorbed in the soil of studied land covers is 8193.45 and 3018.00-dollars ha-1 for surface and subsurface horizons, respectively. Comparing of soil organic carbon (SOC) content over 2004-2018 in the cultivated lands showed the increasing trend about 10.60 and 19.23 percent and in saffron and barley increased by 3.5 and 4.0 fold, respectively. Overall, sufficient information about SOC variation (positive or negative) with time can be effective in sustainable lands management, particularly in arid regions of the country to evaluate effects of different land use managements for increasing in SOCS process.

Bunch fading disorder is one of the important problems in date palm orchards in Iran and influences the quantity and quality of fruits. The aim of this study was investigating the effect of bunch thinning as a management factor on bunch fading disorder, as well as physical, physiological and chemical characteristics of Mazafati date. The experiment was carried out in a randomized complete block design. Four bunch thinning treatments included: T1, shortening of 1/3 total strands from terminal tips in pollination stage (1/3 tippol); T2, removal of 1/3 total strands in kimri stage (1/3 skim); T3, shortening of 1/3 total strands from terminal tips in kimri stage (1/3 tipkim); T4, removal entire of some bunches (traditional thinning as control). Some physical (percent of faded bunches, percent of faded fruits, fruit’s weight, fruit’s length and diameter), physiological (fruit’s proline, total carbohydrates, superoxide dismutase and guaiacol peroxidase enzymes) and chemical (potassium and phosphorus) characteristics of date palms were determined. The results indicated that the percent of faded bunches and fruits in 1/3 tippol and 1/3 skim treatments significantly (P≤0.05) decreased as compared to control. Treatments of 1/3 tippol and 1/3 skim significantly (P≤0.05) increased fruit’s weight (30%), fruit’s diameter (18%), proline (69%), superoxide dismutase (SOD) enzyme (90%) and potassium (K) (13%) as compared to control. It can be concluded that 1/3 tippol and 1/3 skim thinning treatments noticeably decreased bunch fading disorder. Shortening of 1/3 total strands from terminal tips in pollination stage is recommended to date palm owners of the region, due to the concurrency of thinning and pollination stage.