مجله تحقیقات آب و خاک ایران
سال پنجاه و دوم شماره 9 (پیاپی 69، آذر 1400)

Zinc deficiency is the most widespread soil nutritional disorder of the paddy fields that its management is more complex due to its influence on soil properties, and therefore, requires knowledge of the proper application rates, fertilizer types, and application methods in various soil conditions. The current two-year outdoor pot experiment study was conducted to explain the effect of Zn fertilizers types and application methods on the morphological characters, yield, and yield component of the Hashemi rice variety. The three factors factorial experiment was conducted in a completely randomized block design with three replications at the rice research institute of Iran in 2018-2019. The experimental factors were: Zn fertilizer types (four levels), application methods (three levels), and Zn deficit paddy soils (four levels). The results indicated that all fertilizer types and application methods significantly influenced the measured plant and soil characters. The most effective treatments on soil available Zn, plant height, total tiller numbers, panicle length, grain yield was the soil application of 20 kg Zn ha-1 in the source of Zn Sulphate by around 8.6 times, 10, 50, 29.3 and 50%, respectively, and also for straw yield was the three stages Zn foliar application in the rate of 0.5% in the source of Zn Sulphate by about 50%. Thus, it can be concluded that despite the various soil characters of the studied paddy fields, the soil application of 20 kg Zn ha-1 followed by the three stages Zn foliar application at the rate of 0.5% both in the source of Zn Sulphate can enhance the rice grain and straw yield considerably.

In order to estimate the sediment transport discharge in rivers, empirical equations commonly are used. Variables of these equations are flow and sediment properties, such as flow depth and velocity, sediment grain size, or other properties. Estimation of sediment transport by using these equations is based on the measurement of the physical properties. In engineering applications, measuring errors of these properties affect the accuracy of sediment fluxes. The present study quantifies error propagation from the input properties and investigates its effect on the sediment transport calculations. This analysis determines the sensitivity, strengths and weaknesses of four total load equations, including: Engelund and Hansen, Shen and Hung, Molinas and Wu, and Yang and Lim. Due to non-linearity of most of the sediment transport equations, a Monte Calro numerical method is used to compare these equations. Results show that among the input physical properties, flow velocity, sediment grain size, and roughness coefficient mostly affect the sediment fluxes, respectively. Variation of flow depth has the least effect on sediment transport estimations. Results also show that among four investigated equations, Molinas-Wu and Shen-Hung equations are the least and most sensitive to the errors in the input physical data, respectively. In most cases the deference between the Shen-Hung and Molinas-Wu equations is very high and about several hundred percent. Hence, it is recommended not to use the Shen-Hung equation for sediment flux estimation or in hydrodynamic models, except if the physical properties are measured with precision.

Biochar application to soil improve organic carbon and soil quality. The objective of this study was to investigate the effect of biochar and sulfur modified biochar (prepared from sugarcane bagasse and corn residue) on changes in organic carbon and biochemical and microbiological characteristics of a calcareous soil under corn cultivation. This study was conducted in a completely randomized design with five treatments and four replications. Corn residue and sugarcane bagasse biochar and their modified biochar were mixed at 1% (w/w) with the soil sample, and corn was grown in 5 kg pots. The results indicated that the application of biochar and biochar modified with sulfur caused a significant increase in total (56.7-115.4%) and dissolved organic carbon (24.3-60.9%) of the soil, microbial basal respiration (43.8-85.8%), substrate-induced respiration (44.5-98.9%), microbial biomass carbon (54.8-93.4%), dehydrogenase (108.0-114.7) and catalase (105.4-151.6%) activity. Comparison between the two feedstock has revealed that corn residue biochar was more effective in improving total and dissolved organic carbon and soil biochemical attributes than sugarcane bagasse biochar. The positive impact of sulfur-modified biochar on dissolved organic carbon, microbial biomass carbon and catalase activity was significantly greater than the raw biochar. The greatest value of dissolved organic carbon, microbial basal respiration, and substrate induced respiration as well as dehydrogenase, and catalase activity, were related to the biochar treatment of modified corn residue. In general, the results of this study demonstrated that biochar derived from corn residue and sugarcane bagasse could be a suitable organic amendment to improve soil organic matter and soil biochemical properties. In addition, modification of biochar with sulfur and production of acidic biochar can increase its efficiency in improving soil microbial activity.

Organic matter is one of the most important factors affecting soil properties, and understanding its effect on potassium and calcium selectivity can help the management of these two essential nutrients. This study examined the effect of organic matter on potassium and calcium selectivity in a binary exchange system in soil with dominant illite mineralogy. Organic matter was added to soil at a rate of 2%, and then the soil was incubated for ten months. The experiment was performed at an ionic strength of 0.1 M using solutions with a different equivalent fractions of potassium (ẼK) and calcium (ẼCa) between 0 and 1. Then Vanselow (KV), Gapon (KG) and Davis (KD, n = 2, 4, 6) selectivity coefficients and thermodynamic parameters including exchange equilibrium constant (Kex) and free energy changes of the exchange reaction (ΔG°ex) were calculated using exchange data with and without considering the effect of calcium carbonate dissolution on exchangeable calcium values. Comparison of K-Ca exchange isotherms with non-preference isotherm (NP) showed that potassium was preferred over calcium up to ẼK≃0.8, before and after adding organic matter, however at higher ẼK, calcium was preferentially selected. All selectivity coefficients increased with increasing equivalent fraction of potassium in the exchange phase (EK), which indicates that these selectivity coefficients are not true equilibrium constants. Moreover, Kex was less than 1, and ΔG°ex was positive, indicating a preference for potassium over calcium by soil. Also, after the addition of organic matter Kex, increased, and ΔG°ex decreased, indicating a decrease in soil preference for potassium. In addition, results showed that considering the effect of calcium carbonate dissolution on exchangeable calcium value has a significant impact on selectivity coefficients and thermodynamic parameters of exchange in calcareous soil. This highlights the need to pay attention to the dissolution of calcium-containing minerals in the soil during exchange studies.

The Crop coefficient (Kc) is one of the most important parameters in irrigation scheduling. The purpose of this study is to determine silage maize Kc under different irrigation levels using the soil water balance method and presenting the equations for estimating silage maize crop coefficients in terms of the days after sowing during the summer growing season in the Varamin region. The Kc was calculated from the division of actual evapotranspiration (ETa) to reference evapotranspiration (ETo). Soil water balance equation was used to determine silage maize ETa during the growing season. An experiment in the form of split-strip plots based on a randomized complete block design with three replications was conducted in 2019. The main factor included three levels of irrigation, supplying 100, 80, and 60% of maize water requirement (I1, I2, and I3, respectively) and the sub-main factor included two types of irrigation management: pulsed (P) and continuous (C). The value of ETa calculated from the soil water balance method for different treatments ranged from 319.6 to 242.5 mm. Also, the value of irrigation depth during the growing season for full and deficit irrigation treatments ranged from 325 to 195 mm. The mean values of silage maize crop coefficient for initial, middle and final growing stages of full irrigation treatments were 0.27, 1.04, and 0.89, respectively. The water stress coefficients were calculated for deficit irrigation treatments during the growing season. Statistical analysis between ETc calculated from Kc values obtained from the proposed equation in this study and Ks values and Eta obtained from the water balance method indicated that the proposed Kc equation and Ks values in this study have good accuracy in the research area. Therefore, the extracted Ks and proposed Kc equations can be used to estimate silage maize evapotranspiration in the studied region with good accuracy.

Land leveling is a conservation solution to create a uniform slope to integrate, facilitate irrigation and drainage of paddy lands. Despite the positive effects of land leveling, it destroys the physical properties of the soil. The purpose of this study was to investigate the impact of land leveling on the physical characteristics of the soil. This work compares traditional and leveled lands, Balagafsheh and Limuchah areas, which have been leveled for two and five years, respectively. A total of 80 samples were taken, 20 soil samples from each traditional and land leveled plot in the two areas at depth of 0-20 cm by a grid method with dimensions of 20 by 20 meters.  Mean comparison was performed using an independent t-test and SPSS software. The results of comparing the mean showed a significant increase in the percentage of clay, bulk density, penetration resistance in the leveled lands of Limuchah, but in Balagafsheh area, the opposite results were observed. In general, the results indicated changes due to land leveling, such as changes in particle size distribution, structure destruction, and soil compaction without proper management after the implementation of the project, and the reversibility of soil properties is not adjusted solely by relying on the role of the time factor.. Proper management practices such as growing cover crops and returning them to the soil, such as the Balagafsheh area, can exploit the benefits of the land consolidation plan and control the destructive effects of it.

Groundwater is one of the most valuable resources for communities, agriculture, and industry. In the present study, three new artificial intelligence models, including Modified Real AdaBoost (MRAB), Bagging model (BA), and Rotation Forest model (RF), have been developed by the Functional Tree Base Classifier (FT) model to predict groundwater potential in Birjand plain area. Therefore, for implementation, geo-hydrological data of 37 groundwater wells and ten factors of topography, hydrology, and geology were used. The performance of these models was evaluated using the area under the curve (AUC) and other statistical indicators. The results showed that although all the hybrid models developed in this study increased the prediction accuracy, MRAB-FT model (AUC = 0.742) has higher accuracy in predicting potential groundwater areas in Birjand plain. Accurate mapping of groundwater potential areas while maintaining a balance between consumption and operation will help feed the aquifer for optimal use of groundwater resources.

Safflower is one of the most important oily plants whose yield decreases under water stress. Therefore, determining its response to different amounts of irrigation is very important. Hence,  the AquaCrop model for simulating safflower under different amounts of irrigation water was evaluated in this research. For this purpose, surface drip irrigation at three levels (T1, T2, and T3 represent 100, 66, and 33% of water requirement, respectively), furrow irrigation at three levels (T4: 100% water supply, T5: application of 50 mm of water at one time during flowering and T6: rainfed), and subsurface drip irrigation (T7) were considered. The results showed that the accuracy of this model for simulating yield (NRMSE <0.2), biomass (NRMSE <0.2) and water productivity (NRMSE <0.3) were in the categories of good, good and medium, respectively. In addition, the error of this model for simulating yield, biomass and water productivity was 22, 12, and 23%, respectively. AquaCrop efficiency was optimal for the three parameters so that the EF values ​​for these three parameters were more than 0.5. According to these results, the use of the AquaCrop model to simulate safflower is recommended.

This study was conducted to evaluate the application of poultry manure and urea fertilizer in onion in the randomized complete block design with three replications during 2018 and 2019. The treatments were:1-Control (276 kg/haN), 2-Recommended optimal nitrogen limit for the region crop (184 kg/haN)+Optimal consumption of other nutrients, 3- nitrogen consumption 25% more than the optimal limit+Optimal consumption of other nutrients, 4-Consumption of nitrogen 25% less than the optimal limit+five t/ha of poultry manure+optimal consumption of other nutrients and 5-Consumption of nitrogen 25% less than the optimal limit+tent/ha of poultry manure+Optimal consumption of other nutrients. The results showed that the effects of treatments on yield, the concentration of other elements, and nitrate residuals in onion bulbs and leaves were significant at the level of 1% probability. The control had the lowest yield (43.3t/ha) and the highest nitrate residuals (184.3 and 571.2mg/kg, respectively) and the lowest concentrations of potassium, iron, zinc, and manganese in bulbs and leaves. Also, treatment five showed the highest yield (25.1% increase compared to the control), and no significant difference in yield was observed between treatments four and five. The lowest nitrate residuals in bulbs were in treatment four, which was 69.9%, 21.7, 43.3, and 3.4% less than treatments one, two, three, and five, respectively. The application of treatment four, while reducing the consumption of urea fertilizer by 50% and as a result of reducing nitrate in bulbs to less than the critical level and increasing the yield by 18%, resulting in about 11% more revenue than the control.

In recent years, with the development of statistical methods and the application of advanced mathematics, the structure of dependence on extreme phenomena such as drought has been considered. In the present study, multivariate analysis of droughts using SPEI and copula functions and the effect of statistical period length on the occurrence probability of drought was investigated in Arak synoptic station. For this purpose, precipitation and observational temperature data and global climate database (CRU) networks have been collected for the selected station, and two statistical periods of 100 and 37 years have been selected for this research. Then, the characteristics of duration and severity of drought were extracted and at different time scales (1, 3, 6, 9, and 12), and its dependency structure was calculated by Spearman’s rho and Kendall’s tau correlation coefficients that it shows there is a significant correlation between severity and duration of drought except on one-month scales. After determining the best fitted marginal distributions on the drought characteristics, the fitness of five different copulas for developing the bivariate distribution of severity and duration of drought was examined. The results showed that at Arak station for both statistical periods of 100 and 37 years, Clayton and Gumble-Huggard copula functions, respectively, due to having the highest value NS (0.9, 0.9) and the lowest values of NRMSE (12.9, 7.9). The results also showed that the 37-year statistical period was suitable for the study of droughts with the condition "or" but in the case of "and" and the intensification of droughts, the joint return period reaches nearly 45 years. Therefore, it is recommended that a statistical period of 100 years be used to analyze the droughts in the study area.

Transboundary Rivers are important common water resources that could bring benefit set or basket of benefits in areas of social, environmental, commercial, and political, for all countries located in the shared basin. The basket of benefits gained from the cooperation between countries effectively achieves the desired stable point of interaction, which is not considered in many studies in this field. In this paper, a model was presented based on evolutionary game theory in which the strategies of countries in using water of a transboundary river were analyzed and evaluated. Evolutionary stable strategies (ESS) were examined and countries’ behaviors were analyzed based on changes in their revenue interests. This model was applied to a basin shared with three countries and provided a framework for recognizing the behavior and management of countries' interests depending on whether they are upstream or downstream. Finally, numerical simulation was done to examine the evolutionary process of strategies and the effect of parameters on interactions between countries. The results of the simulation demonstrated the significant effect of the upstream country's basket of benefits (benefits other than water consumption benefits) on the interactions between countries and the final strategic stable point. Upstream country’s basket of benefits obtained from choosing cooperation strategy was changed to -1, -2, 2, and 5 percent compared to its water benefit obtained from choosing non-cooperation strategy by upstream country. The speed of convergence of the possibility of cooperation or non-cooperation of the upstream country was examined. It was concluded that even a one percent increase in the basket of benefits related to the water benefit would be lead to tripartite cooperation between countries. These results can be a theoretical guide for countries living in a transboundary river basin to interact with each other considering the role of benefits other than water benefits.

This study aims to investigate and analyze the results of geotechnical experiments on sediment samples taken from the Latian Dam reservoir in Tehran province. After the site visit, eight important stations were identified for surface sediment sampling, and on these sediments, common soil mechanics tests such as grain size analysis, determination of specific gravity, consolidation, compaction, and triaxial were performed to determine soil resistance and consolidation parameters. The present study results showed that by approaching the dam wall, soil water content increased by more than two times. This is due to the smaller size of the soil grains so that the percentage of clay and silt near the dam wall was more than 89%. According to the compaction test results and empirical equations, it was found that after 100 years of sediment deposition in the Latian dam reservoir, the dry density of the sediment will be equal to 1.128 g/cm3. In addition, from the triaxial test results, it was found that the cohesion and internal friction angle parameters of the sediments were equal to 0.51 kg/cm2 and 26.1°, respectively.

Areas where waste is buried based on engineering design, which is one of the waste disposal methods. Leachate accumulation in landfills can adversely affect downstream groundwater resources by infiltrating the aquifer. In this study, we tried to investigate the potential of leachate penetration and the plume contamination caused by leachate pools inside and outside the landfill, respectively, using two methods of electrical resistivity tomography (ERT) and vertical electric sounding (VES). For this purpose, at a distance of 60 and 580 meters from the leachate basin, VES data were collected with a transmitter length of 200 meters and ERT with a length of 120 meters and electrode distances of 2 meters. Examination of geotechnical and VES data in the study area shows an impermeable layer with an alternation of clay-madstone and calcareous-marl layers at a depth of about 10-15 meters the percentage of the clay were increased. The ERT data in profile number 1 shows that at a distance of 32-76 meters from the beginning of the profile at deptt of 9 meters there are areas with low electrical resistivity, which indicates the area of leachate penetration, but in the other section of profile leachate deep penetration are not visible due to the Madstone and Siltstone impermeable layers. However, in the ERT data in profile number 2, the presence of an impermeable layer prevents the infiltration of leachate to the downstream and lower depths, which indicates the proper selection of the landfill. Therefore, contrary to what can be seen in the VES data, the study area is not homogeneous in terms of permeability to leachate in the two dimensions of ERT, but the presence of an impermeable layer prevents the deep transfer and infiltration of leachate to the aquifer.

The river is one of the most important water sources for drinking and agriculture. Therefore, evaluating and modeling the water quality of rivers and examining its qualitative effects on human life, living things, and the environment is undeniable. In this study, the water quality of the Beheshtabad River was simulated using the QUAL2Kw simulation model. The water quality of this river in its two tributaries was analyzed by designing two scenarios to improve it downstream. The simulated qualitative parameters (temperature, Ec, TS, DO, BOD, COD, pH, nitrate, orthophosphate, ammonium, and fecal coliform) were simulated in two scenarios with different flow rates. The results show that by preventing the discharge of water from the upstream rivers (Kiar and Juneqan) due to high pollution and also the addition of water from Bagh-e-Rostam spring along the route, the water quality of this river will improve downstream. Including BOD concentration will improve from 7.32 to 4.23 mg /L, COD parameter concentration will improve from 19.30 to 12 mg/L, DO parameter concentration from 4.9 to 5.9 mg/L, and fecal coliform parameter concentration from 1500 to MPN/100 mL160.

As the veins of the Earth, Rivers have a determinative role in regulating the functional behaviors of their linked ecosystems and supporting human life. This research was conducted to address the major issue to assess the river's health and survival condition alongside its vulnerability potential, using a benthic-based sustainability index. For this purpose, river-bed sediment oxygen demand (SOD) rate and its associated factors, including Texture, fine-PSD, Nutrients (TOM), besides some basic field parameters of river-water were measured. All required samples were collected from 9 sampling points located on the target zones of Karkheh River in due course. SOD data with regard to related factors were calculated and analyzed. The rates of SOD ranged from 0.71 to 1.74 g O2/m2/day. Further, this index was classified in varied quality domains. Afterward, a predictive equation was determined among SOD rate and its associated parameters using MATLAB software. Finally, the results revealed that the river health suitability in the research area is in categories moderately clean and slightly degraded during the study period. Additionally, the increase in TOM concentrations, together with a decrease in sediment particle size, led to an increase in SOD-rate accordingly. The source pollution load reduction rate under the optimal suites of BMPs in the range of 15 to 66 percent was also one of the outputs of this research.  In conclusion, the consequences of this study can be used as a rapid diagnostic tool to support regional water authorities and other stakeholders to promote the best practices for protecting the health condition of the riverine system, focusing on selecting the appropriate discharge points along the receiving watercourse and on effectively managing the drain-waters/effluents.