نشریه پژوهش های حفاظت آب و خاک
سال بیست و نهم شماره 2 (امرداد و شهریور 1401)

At the arid and semi-arid climates which the rainfed farming has a high degree of importance, it is essential to evaluate both the effective factors on the rainfed crop yield and its predicting as well. In this respect, it is unavoidable to have a special consideration for some tolerable crops such as barley. The aim of the current study was to assess the possibility of rainfed barley annual yield prediction using some drought indices at a semi-arid climate.

By calculating SPEI, EDDI and SPI drought indices for four growth stages of rainfed barley including sowing-emerge, emerge-tillering, tillering-stem and stem-flowering at the Sararoud-Kermanshah station, a number of 12 time series of these indices were extracted during 2000-2015 period. The cross-tabulation was used to evaluating the overall relationship between drought indices and rainfed barley annual yield and to modeling rainfed barley annual yield based on drought indices, the best subset-based multiple linear regression model and Principal Component Regression (PCR) were applied at two different stages. The modelling procedure performed in two overall cases including considering a unique drought index and considering a combination of three different drought indices cases.

the results of cross-tabulation technique showed an appropriate relationship between rainfed barley annual yield and drought indices. Therefore, a potential is available to use drought indices to predict rainfed barley annual yield. Based on the results of considering a unique drought index case, the highest (63.6%) and lowest (54.1%) values of coefficient of determination between rainfed barley annual yield and drought indices were for SPEI and EDDI indices, respectively and a value between them (62.4%) for SPI. The values of these indices were appeared at the model during the sowing-emerge and tillering-stem stages for SPEI and SPI and sowing-emerge and stem-flowering stages for EDDI. By considering the combination of three different drought indices case, the results revealed that the best multiple linear regression model is obtained by presence of SPEI (during tillering-stem and stem-flowering stages) and EDDI (during sowing-emerge and tillering-stem stages) indices in the model with a good coefficient of determination (R2= 78.7% and R2adj= 69.2%). However, the high value of Variance Inflation Factor (VIF) revealed that it is necessary to solve this issue by considering the Principal Component Regression (PCR) model. By applying PCR model to predict rainfed barley annual yield, the coefficient of determination for the PCR (78.2%) showed a negligible decrease compared to the multiple regression model. However, the adjusted coefficient of determination properly improved to 71.7%. By considering the PCR model as the final model of predicting rainfed barley annual yield, the cross-validation results of this model led to obtaining R2=58.5% and RMSE=572.3kg/hec (equal to 22% of the mean of annual yield).

The overall results of this research showed that applying different drought indices could lead to increasing the explained variance of rainfed barley annual yield. The overall results of this research showed that the occurrence of drought during the emerge-tillering stage does not have a considerable impact on the rainfed barley annual yield. With respect to the higher role of the tillering-stem stage in the regression models, this stage was detected as the most important effective period on the rainfed barley annual yield. Therefore, among different growth stages, occurring drought in the tillering-stem period is expected to lead to a lesser amount of annual yield.

Oil pollutants are inevitable consequence of rapid population growth and the process of industrialization. Their spread in soil can affect many soil properties, especially aggregate stability. Particle size distribution and aggregate stability are of the main physical and hydraulic characteristics of soil that study of these indices are the basis of soil conservation strategies and are very important parameters in identifying the status of soil structure. Iran is an oil-rich country and the effect of different petroleum compounds on aggregate stability and stability indices including mean weight diameter and geometric mean diameter of aggregates in soils of different textures have not been studied so far. Therefore, this study aimed to investigate the effect of different levels of crude oil, kerosene, and gasoline as the three high-consumption petroleum products on the stability of aggregates in three soils with clay loam, sandy loam, and loamy sand textures.

In this study, the effect of 0, 1.5, 3.5, and 4.5% levels of crude oil, kerosene, and gasoline on the stability of aggregates in clay loam, loamy sand, and sandy loam soils was investigated in a factorial completely randomized design experiment. Studied stability indices were the mean weight diameter and geometric mean diameter of aggregates deterimined using both dry and wet sieving approaches. Finally, the results of the research were analyzed using EXCEL and SAS statistical softwares and the means of each separate treatment as well as their interactions compared using the Duncan's multiple range test at the 5% level.

The results showed that the mean dry weight of aggregate diameters in the loamy sand and sandy loam soils were significantly lower than that of the clay loam soil by nearly 72% and 56%, respectively. The reductions were about 78% and 69% for the dry geometric mean diameter of aggregates. Furthermore, the dry mean weight diameter of aggregates in the soils treated by kerosene and gasoline were more than that of the crude oil- treated soils by nearly 17% and 25%, respectively. The mentioned increaments were about 22% and 35% for the dry geometric mean diameter. The wet mean weight diameter of aggregates in the loamy sand soils was significantly higher than that of the clay loam and sandy loam soils by nearly 20% and 35%, respectively. Furthermore, the wet geometric mean diameter of aggregates in the loamy sand soils was significantly higher than that of the clay loam and sandy loam soils by nearly 91% and 12%, respectively. The wet mean weight diameter of aggregates in the soils treated by kerosene and gasoline was significantly lower than that of the crude oil- treated soils by nearly 32% and 8%, respectively. Furthermore, the wet geometric mean diameter of aggregates in the soils treated by kerosene and gasoline was significantly lower than that of the crude oil- treated soils by nearly 34% and 14%, respectively.

Generally, results indicated that the application of low levels of petroleum products significantly increased the wet and dry mean weight diameter of aggregates and geometric mean diameter of aggregates; whereas, high levels reduced the above-mentioned attributes. The results of this study can be used in both aspects of identifying and monitoring the properties of oil-contaminated soils for their remediation and making appropriate management decisions, as well as conservation of soils against the destructive erosion phenomenon.

Since water and soil are important components of the ecosystem ‎and their quality reduction affects the environment and agriculture, it is necessary to determine ‎the effects of pesticides on soil and water resources and determine their residual concentration ‎levels in the land. Agriculture, especially paddy fields, should be controlled and managed. ‎Therefore, the purpose of this study is to determine and evaluate the level of residual ‎concentrations of organophosphate pesticides in soil and water samples of Rudbar County and to ‎investigate their ecotoxicological status.‎

In this study, the multiplicity of 12 stations was determined using a ‎systematic random method in the paddy lands of Rudbar County. In total, 24 samples including ‎‎12 water samples and 12 soil samples were collected. Water sampling was performed in 1-liter ‎dark-colored bottles and soil sampling was performed from the surface layer according to the ‎standard method. All samples were transferred to a laboratory in a freezer containing dry ice. ‎Organophosphate pesticides were measured using the EPA 8041b standard method. All analyzes ‎were performed by gas chromatography with the mass detector in Aria Shimi Sharif Company. To ‎study the ecotoxicological status of pesticides, two databases named National Pesticide ‎Information Center and Pesticide Properties Database were used. The two databases are affiliated ‎with Oregon State University, the US Environmental Protection Agency, and the University of ‎Hertfordshire. Statistical analysis of the data included analysis of variance using one-way ‎ANOVA test, comparison of means using Duncan's test, correlation using Pearson's method, and ‎analysis of principal components using the covariance method.‎

Based on the results, 11 organophosphate pesticides were identified in water and soil ‎samples of Rudbar paddy fields. Ethion in soil and Diazinon in the water had the highest residual ‎concentrations. Sheikh Ali Tues 1 and 2 and Mirzagolband 1 stations with the values of 4.55, ‎‎3.99 and 3.49 ug/kg had the highest amount of Ethion toxin residues in the soil. In addition, ‎Sheikh Ali Tues 2, Mirzagolband 1, and Halimeh-Jan stations with 3.96, 1.71, and 1.68 ug/L, ‎respectively, had the highest amount of Diazinon pesticide in water samples. The results showed ‎that the downstream lands in the area of Imamzadeh-Hashem compared to the upstream lands in ‎Rudbar city have a higher concentration and load of pollution. The mean concentration remaining ‎in soil samples (0.987 ug/kg) was higher than in water samples (0.304 ug/L). Based on the results ‎of pesticides Diazinon, Methyl Parathion, Azinphos Methyl, Malathion, and Ethion in the studied ‎stations showed a significant difference. A comparison of the mean residual concentrations of ‎pesticides with their physicochemical and ecotoxicological properties showed that in terms of ‎potential risk and toxicity for aquatic organisms, the concentrations of BetaMevinephos, ‎Malathion, and Azinphos Methyl pesticides were 0.043, 0.573, and 0.272 ug/kg, respectively. Has ‎been very high, which has put these pesticides in a situation of high and toxic danger to aquatic ‎organisms in the region.‎

Extreme use of pesticides on agricultural land has caused environmental problems. ‎As a result, monitoring and evaluation of pesticide residues in paddy fields are very important ‎because contaminated effluents are discharged directly from rice fields into rivers, depending on ‎several factors. Due to the high levels of residual concentrations of some organophosphate ‎pesticides in the region, it is necessary to hold training courses on farmers' familiarity with the ‎dangers of pesticides to prevent, control, and reduce pollution under the supervision of experts. ‎Also, to fight non-chemically against pests, it is suggested to use the Trichogramma bee in the ‎form of Trichocart to fight the rice stem-eating worm, colored traps, and attractants in paddy ‎fields.‎

The use of modern irrigation systems due to the increase in efficiency and productivity of water consumption is a basic solution compatible with water shortage conditions. The use of proper irrigation methods to maintain food safety and reduce water requirements is a global issue. The most important goals of the implementation of these systems are quantitative and qualitative protection of water and soil resources and sustainability of agricultural production.

In this study, technical and hydraulic evaluation of seven new irrigation systems (integrated irrigation, Movable Sprinkler Solid-Set Irrigation Systems and Trickle Irrigation) implemented in Shahrekord, Bon and Saman cities in Chaharmahal and Bakhtiari province was performed. To evaluate integrated and Movable Sprinkler Solid-Set Irrigation Systems, Christiansen uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low quarter (PELQ), application efficiency of low quarter (AELQ) in two block scales were experimented and the whole system were calculated. To evaluate drip irrigation systems, uniformity indices of water emission throughout the system (EU), potential application efficiency of low quarter (PELQ), application efficiency of low quarter (AELQ) were calculated.

The results showed that the values of CU, DU, PELQ, AELQ indices for the tested block in integrated and Movable Sprinkler Solid-Set Irrigation Systems were equal to 68.6, 59.38, 46.85 and 58.56 and and for the system, 67.01, 58.48, 45.2 and 56.5. Was calculated. Also, EU, PELQ and AELQ index values for drip irrigation system were 55.62, 51.91 and 53.83. The results showed that the above systems have a good infrastructure and most of the problems of these systems are related to the phase of operation and maintenance of these systems by users.

The main problems of these systems that have led to a decrease in performance evaluation criteria are the deficit irrigation, lack of knowledge of users and lack of training on how to use the system properly (pressure regulation, periodic visits to the system, interest Correct and principled removal, etc.), changes in high pressure and uneven distribution in the system, changing the irrigation cycle, using more sprinklers and non-compliance with the proposed cultivation pattern in accordance with the design booklet and the use of drippers are inappropriate. Therefore, according to the comprehensive review, it is suggested that training courses should be given to farmers by changing the type of system from traditional to modern methods, and farms that are optimal in terms of exploitation should be identified and visited by others.

Due to the scarcity of water resources and increasing human demand, the optimal operation of reservoirs has become one of the most important issues in the world. In this regard, the correct and optimal operation of dams is one of the most efficient tools for water resources management. Due to the large number of decision variables, relationships, and constraints in the problems, reservoir management, and optimization have many complexities. Therefore, many researchers in their research have paid special attention to this issue. In this research, a new algorithm namely Atom Search Optimization (ASO), which is derived from the concepts of molecular dynamics, will be developed for multi-reservoir water resource systems. On the other hand, failure to implement appropriate policies to protect the soil has led to an important phenomenon of erosion in the lands above the reservoirs, one of the negative consequences of which will be sedimentation. The transfer and accumulation of suspended sediments, in turn, will reduce the useful volume of the reservoir, which is neglected in most reservoir optimization issues. However, in this study, the optimal operation of a single reservoir dam is investigated by the Atom Search Optimization algorithm in terms of monthly sediment yield.

First, the performance of the atom search algorithm on mathematical benchmark functions will be investigated. Then, by performing sensitivity analysis to logically determine the effective coefficients of the algorithm and selecting the appropriate number of particles and the number of iterations of each operation, the performance of the algorithm on conventional systems of four and ten reservoirs is analyzed. In order to supply water downstream of Dez Dam, considering the important issue of monthly sediment flow in the reservoir, the atom search algorithm and four other common algorithms are used. The results are modified by selecting the objective function value criteria, RMSE, MAE, NSE, and PBIAS values and prioritized using TOPSIS and Modified-TOPSIS ranking techniques.

The performance of the atom search algorithm on conventional systems of four and ten reservoirs is analyzed, which shows the results of 95.33% with an absolute optimal solution of four reservoirs, ie 308.29, and 89.67% with an absolute answer of ten reservoirs, 1194.44. Also, by comparing the atom search algorithm and four common Salp Swarm Algorithm (SSA), Sine Cosine Algorithm (SCA), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA) in a single reservoir system under deposition, the absolute superiority of the ASO search algorithm was demonstrated.

The use of an atom search algorithm in solving optimization problems in the field of water resources management is recommended, especially in terms of the effectiveness of soil protection and sedimentation of reservoirs.

Determining the type, extent, and spatio-temporal changes of land use and land cover is very important in determining the hydrological characteristics of watersheds. Satellite data is the fastest and cheapest tools available to researchers in this regard. The study area in this study is Hablehroud watershed, whose flow decline over the past decades resulted in intensification of the conflict between the upstream (the Tehran province) and downstream (the Semnan province) stakeholders. Since, the land use change is considered one of the causes of the watersheds’ hydrological regime, this study aims detect, quantify, and predict the land use changes as well as to analyze the land surface vegetation cover in the Hablehroud watershed.

In this study, in order to identify the land use types of the Hablehroud basin, a supervised object-oriented classification of Landsat series images related to 1987, 2002 and 2019 was performed in Google Earth Engine software. To determine the classification performance, several ground truth points is required. In this study the ground truths were acquired through field visits and consultation of the high-resolution images of the Google map. The Markov chain and CA-Markov models within the MOLUSCE module, which is one of the software extensions of QGIS spatial information system software, wer used to simulate land use changes and analyze their dynamics in the study area. Moreover, the NDVI index was calculated to assess the spatio-temporal changes of the vegetation status of the study area through using the Google Earth Engine software.

The results indicate that the classification method used in this research has an overall accuracy percentage of more than 88 and a Kappa coefficient of more than 0.86 in all the time periods investigated. It is also observed in 2019, compared to 1987, we see an increase in irrigated arable land by about 67.5 square kilometers, an increase in rainfed agricultural land by about 20 square kilometers and an increase in residential areas by about 21 square kilometers. However, the grade 1 and 2 rangelands have decreased, which is about 240 square kilometers in the grade 1 rangelands and about 196 square kilometers in the grade 2 rangelands. While the extent of the poor rangelands has increased by about 327 square kilometers. If this trend continues, during 2019 - 2051, the extent of the irrigated areas, poor and medium class rangelands will increase about 20, 50, and 50 square kilometers, while the extent of the good rangelands will decrease about 127 square kilometers. The extent of the residential lands will increase too. trend. The results also show a significant downward trend in the average NDVI index of the basin, indicating retrogression in the vegetation status of the basin. Vegetation retrogression is more intense around residential areas and rivers and downstream areas of the basin.

The study of land use change trends in Hablehroud basin shows that due to human interventions, in significant parts of the basin, natural vegetation has been replaced by agricultural, horticultural and residential areas. The quality of the dominant natural cover of the region (rangeland) has also undergone a significant retrogression process Therefore, due to population growth, urbanization and development of industries and tourism, sharp decline in the discharge of the Hablehroud basin and the spread of conflict between stakeholders in the region, it is suggested that the main focus of the policies and management measures should be on effective planning, especially the management and optimization of human interventions through the development and implementation of land management plans and optimization strategies and save water consumption in this watershed.

Simultaneous improvement of water and nitrogen use efficiency in paddy fields is necessary to reduce the environmental- related issues. Rice, as one of the most important crop, provides the main food of more than half of the world's population. According to the latest available statistics, in the crop year 1396-97, the rice cultivated area the country was 622991 ha, which mainly belongd to the five provinces of Gilan (35.3%), Mazandaran (34.3%), Khuzestan (10.9%), Golestan (9.9%) and Fars (3.4%). Among different provinces, Mazandaran province is the main producer of rice in the country with the production of 1113715 tons of rice. Additionally, rice is the predominant crop in Mazandaran province.

The required field data of Daylamani rice cultivar were obtained during two rice growing seasons (2011-2012) from one ha consolidated paddy field in Sari, Mazandaran province. Data from 2011 were used for calibration and data from 2012 were used for validation of the CERES-Rice model of DSSAT V4.7.5 software package. By using the validated model, the effect of different scenarios of water and nitrogen fertilizer management on water use efficiency (WUE), economic water use efficiency (EWP), physiological efficiency of nitrogen consumption for grain production (NUEg), harvest index and nitrogen harvest index (NHI) were evaluated. The calibrated model was then applied to evaluate the combined effect of three types of irrigation management including continuous flooding (I1), intermittent irrigation with 5 (I2) and 8 (I3) days irrigation frequency and six N fertilizer management treatments including N1 (50% at planting (P), 25% at tillering (T) and 25% at clustering (C)), N2 (25% at P, 50% at T and 25% C), N3 (25% at P, 25% C and 50% at T), N4 (fertilization at C), N5 (fertilization at T) and N6 (fertilization at P).

The minimum (832 kg/ha) and maximum (3640 kg/ha) grain yield were obtained in I1N6 and I3N5, respectively. The simulations showed that the effect of fertilization time and type of irrigation were not independent of each other. I3N5 resulted in maximum HI (0.39), minimum soil evaporation (173.4 mm), maximum WUE (one kg/m3), maximum EWP (12×104 Rials/m3), minimum nitrate losses (52.47 kg/ha), the highest nitrogen fertilizer uptake (99 kg/ha), maximum NUEg (one) and minimum nitrogen stress (0.05). Also, the maximum NHI (0.37) belonged to the I2N5 treatment.

Based on the results, among the applied managements, according to the components of crop yield, harvest index, water productivity, EWP, NUEg, nitrogen uptake, nitrate leaching and NHI, 8 days irrigation frequency was the best option in terms of irrigation management. Also, the use of I3N5 treatment as a superior combined- treatment under both fertilizer and irrigation management in the present study is recommended in terms of water and N use efficiency in the paddy fields of the province.