مجله تحقیقات آب و خاک ایران
سال پنجاهم شماره 3 (پیاپی 41، امرداد 1398)

In recent year, application of biochar in soils of dry and semi-arid regions has been considered for increasing soil organic carbon. However,  few reports are available about the effect of biochar on nitrogen cycling in such soils. The purpose of this study is to investigate the effects of cow manure and its biochar on some N cycling processes and related biological properties in a calcareous soil. For this purpose, 0, 1, 2 and 5% of cow manure and its biochar were added to a calcareous soil and then the treated soils incubated for 30 and 90 days. The results showed that the microbial biomass nitrogen and urease activity in the soils treated with cow manure increased more intensively against the soils treated with biochar. The application of 2 and 5% of biochar increased the nitrogen mineralization by 20.5 and 32.3% at 30-days incubation, and by 103 and 106% at 90-days incubation. Addition of cow manure to soil led to a significant increase in nitrogen mineralization by 38-233% at 30-day incubation and 21- 105% at 90-day incubation. At 30-days of incubation, nitrification increased in soils treated by 5% of biochar. The addition of biochar to the soil increased nitrification by 10-50% compared to the control at 90-days of incubation. The addition of cow manure to soil increased nitrification by 1500-300% and 39-95% in comparison to the control after 30 and 90 days of incubation. In general, our findings showed that the use of cow manure biochar compared with cow manure could reduce nitrogen mineralization and nitrification and prevent rapid nitrate leaching.

Satellite-based precipitation estimations are important and necessary because they are used to compensate the limited rain measurements in areas where there is no continuous monitoring of rainfall due to the dispersion of rain ague networks. Satellite-based precipitation estimation systems can provide information in areas where rainfall data are not available. Therefore, the accuracy of this type of data is very important. In this study, rainfall data of two long-term satellite data sets (FARSI-CDR and PERSIANN-CCS) at the upstream of Maroun Dam (Dehno, Ghale-Raeesi, Idenak, Margoon stations) during 2003-2014 were used and evaluated on daily, monthly, seasonally and annually basis. The results show that the annual precipitation of each dataset is underestimated in all stations, but the PERSIANN-CCS model compare to the PERSIANN-CDR has better estimations for annual observations. For estimation of seasonal precipitation, the results indicate that the PERSIANN-CCS model is better than the other one for rainfall estimation and rainfall detection. For estimation of monthly and daily precipitation, the results indicate that PERSIANN-CDR data are more appropriate than the other data set. Also, regarding to POD (probability of detection) and FAR (False alarm rate) estimated data, It was found that according to POD index, PERSIANN-CCS precipitation daily data and according to FAR, daily precipitation data of PERSIANN-CDR model have better performance in detecting rainy and non-rainy days.

Nonlinear weirs have relatively high discharge capacities in low hydraulic loads and their performance is reduced due to submergence of the outlet key in high hydraulic loads. Labyrinth weirs are hydraulic structures used for water level adjustment and flow control in reservoirs. The labyrinth weirs performance is not satisfactory in high hydraulic loads due to interference of flow blades, turbulence and submergence in the outlet key. Therefore, the purpose of this study was to investigate the effect of parapet wall location on weir inlet submergence. Thus, the inclined parapet walls were used on trapezoidal labyrinth and piano-key weirs, which had 60 and 30 cm length (B = 60 and 30 cm) with 1 and 0.5 in slope (B′ = 1 and 0.5). The results showed increasing the parapet wall heights and lengths leads to a 50-percent decrease in the discharge coefficient. The weirs performance also increases by 33 percent as the flow rate increases. The installation of parapet walls on the labyrinth weirs showed better performance (up to 30%) as compared to the piano-key weirs with the same plan.  Also the installation of parapet walls at the weir outlet showed a better performance (5-10%) as installed at the weir inlet. It was found that the flow rate is directly related to the discharge coefficient; hence, the efficiency drop is reduced about 40% in high discharge rates by setting the parapet walls at labyrinth and piano-key weirs.

Irrigation scheduling is very important under water stress condition. To investigate the crop water stress phenomena, several indices have been presented, of which one is CWSI. In order to investigate the ability of this index in irrigation scheduling of Maize (SC704), a research in a randomized blokes design with four experimental treatments was conducted in Khoram Abad region in 2011. Experimental treatments including IR1: 100% water requirement, IR2: 80% water requirement (by Regulated deficit irrigation), IR3: 60% water requirement (by Regulated deficit irrigation) and IR4: 50% water requirement (by Partial root zone drying management).  The results showed that the amount of CWSI was significantly affected by water stress.  The CWSI index for IR1, IR2, IR3, and IR4 treatments were 0.17, 0.21, 0.39, 0.29 and the amount of yield were 21560, 19500, 12560 and 14860 Kg/ha, respectively. In this study, the best treatment was IR1 (with the minimum CWSI and the maximum Yield) and the worst treatment was IR3 (with the maximum CWSI and the Minimum Yield).  Based on CWSI index, the value of water stress in IR4 treatment was less than the water stress value of IR3 treatment (The CWSI index dropped by 11.4 percent and the amount of yield increased by 18.3 percent). In this research, the relationship between the corn forage yield and CWSI index was obtained with high correlation. Regarding the variation of CWSI under different treatments, it can be stated that the CWSI index is able to evaluate the water stress and estimate the corn forage yield.

This study was carried out to evaluate Hamody irrigation network (in an area of 3079 ha) using classic and new classic irrigation efficiency concepts. For this purpose, firstly the main district’s water inputs (irrigation, rainfall and canal releases) and outputs (actual crop evapotranspiration, drainage outflow and canal seepage) were measured or estimated during the hydrological years (2006-2009). Then, the application efficiency (classic concept) and the net and effective efficiencies (neoclassic concept) were estimated at the network level. Finally, different scenarios of water allocation were evaluated by considering new concepts of irrigation efficiency. The assessment scenarios include 65, 75 and 85% of water supply needs, 100% Crop Water Requirement (CWR) and a fraction of CWR without significant reduction in yield. The annual average outflows were 16% higher than the inflows, presumably due to canal seepage and lateral groundwater inflows from neighboring lands. Distribution, application and total efficiencies were estimated 68, 53 and 44%, respectively, indicating low irrigation performance in the irrigation network. Despite the high volume of applied irrigation water, the actual ET was 19% less than the potential ET, indicating water-stress and crop yield reduction. The assessment of surface irrigation systems using new classical approach showed that the net (0.77) and effective (0.65) efficiencies were more than the classical efficiency (0.53). The results of this study showed 19-47% water saving in allocation scenarios using the new concepts of efficiency.

Root water uptake is considered as a major factor for  predicting plant transpiration and the product yield. In general, the water root uptake models are divided into two macro- (experimental) and micro- (physical) groups. The physical models require more hydraulic parameters, while empirical models are simpler and require less input data. The aim of this study was to compare the performance of two empirical models and a physical model to predict the root water uptake of tomato under greenhouse conditions. Hence, the generalized likelihood uncertainty estimation (GLUE) was used to calibrate the models (hydraulic parameters of soil and root water uptake). The results of the sensitivity analysis of different models showed that the root water uptake is more sensitive to soil hydraulic conditions than the root characteristics. The results indicated that among the soil hydraulic parameters, the root water uptake shows more susceptibility to the coefficients of shape (λ) and the saturation moisture content (Өs). Among the root characteristics, the most sensitive parameter is the longitudinal density of the root. The results also revealed that the Van Genuchten model combined with the GLUE method has well simulated the root water uptake, as the parameters of R2, NS, NRMSE, MAE, ME, and d were 0.79, 0.69, 14.12, 0.75, 0.69, 0.86, respectively.  The integration of root water uptake models as a sub-model in the agro-hydrological models appears to be a useful tool for predicting the plant transpiration, the product yield as well as water management in the field.

The increase of wastes and their management are considered as an important environmental and economic problem. In this study, the oily sludge of oil refinery and lignocellulosic waste from elm tree were used as raw materials for preparation of composite adsorbents. Composite adsorbents were prepared using carbonization at 500 ˚C and chemical activation by zinc chloride at 800 ˚C and their efficiency for removal of furfural from aqueous solutions were investigated. Results of furfural adsorption, BET, SEM and FTIR analysis showed that the activated composite, due to formation of micropore and mesopore structures, has  a more higher specific surface area and efficiency, as compared with carbonized composite. The BET of carbonized and activated composite was 3.53 and 691.7 m 2/g and the percentage of furfural adsorption was 10.3 and 96.7%, respectively. Based on the obtained results, the activated composite adsorbent can be used as an alternative of commercial activated carbon for wastewater treatment.

The objective of this study was to investigate the  concentration of heavy metals, dispersed from Khuzestan Steel factory, in the soil and various plants  of surrounding area. For this purpose, the Leaves samples from trees, shrubs, grass and soil samples from their rhizospheres were collected in dominated and opposite wind direction from the factory. Plant samples were divided into two groups; of which one group was washed with distilled water and HCl and another was not washed. Heavy metal concentrations (Fe, Cu, Cd, Pb, Zn) were measured in plant and soil samplesby flame atomic absorption spectroscopy. Results showed that the heavy metals concentration in plants in wind direction is almost 1.5 times more than the opposite direction. Airborne metal deposition has occurred in this region because the heavy metal concentrations in unwashed samples were more than the ones in washed samples. Based on the results obtained from this study, it can be concluded that Khuzestan steel factory activity is one of the pollution  sources in the proposed region which threated the environment of Ahvaz.

To examine the effects of two climatic parameters of average rainfall and average annual temperature on water resources status toward the population parameters in seven grade-2 watersheds, located in Persian Gulf and Oman Sea, the observation data of 180 synoptic stations in the proposed watershed and historical data of the CORDEX project for the 20-year statistical period (1986-2005) considering RCP2.6, 4.5 ,8.5  climate scenarios were used in this study. Then, the EC_EARTH, CNRM and GFDL climate models were used for the upcoming periods of (2006-2030) and (2031-2050). Finally, the ability of each model to fit the water stress index (based on the lowest error with the base course) for each watershed was studied. The results of this study showed that the all three climate models (EC_EARTH, CNRM and GFDL) predicted MOND and KOL-MEHRAN watersheds, respectively, as the highest and lowest water resources status in relation to population parameter in upcoming periods of (2..6-2.30) and (2031-2050) and under RCP2.6 ,4.5 and RCP8.5 scenarios, relative to the observational water stress index .

Solar radiation arriving to the land surface is one of the major variables that is used in projects and hydrological, agricultural, meteorological and climatic models. In this study, the functionality of the principal component analysis (PCA) and the entropy theory (EN) for determination  of inputs to multilevel perceptron artificial neural network (MLP), artificial neural network, radial basis function (RBF), support vector machine (SVM)and genetic programming (GEP), was investigated for estimation of solar radiation at two stations (Kerman and Mashhad) during 1984-2005 and 1980-2004 periods, respectively. The average temperature, mean water deficit pressure, minimum temperature, maximum temperature, sunshine, relative humidity, dew point temperature, hourly vapor pressure, horizontal visibility and water content were selected as inputs of pre-processing methods. The obtained results  in Kerman station showed that the ENT-MLP model with RMSE=38.36 (Mj /m2) and R2 = 0.93 have had the best performance. Also in Mashhad station, PCA-MLP model with RMSE=79.75 (Mj / m2) and R2 = 0.77 had the best performance. In general, the both pre-processing  principal component analysis and entropy theory were recognized  as the proper methods for determination  of estimating models input to estimate  solar radiation.

Optical remote sensing of earth surface processes commonly relies on the Red, Green, Blue (RGB), Near Infrared (NIR) and Shortwave Infrared (SWIR) electromagnetic bands. In soil-moisture estimation method using optical remotely-sensed imagery, by assuming a linear relationship between the Red-NIR reflectance, the line of bare soil (soil line) is established as the base and then moisture isoclines are assumed perpendicular to the soil line. This study is intended to show that this assumption is not consistent with the actual Red-NIR space geometry, which in many cases introduces soil moisture estimation errors. Therefore, a new mathematical transformation method was proposed to the original Red-NIR space followed by newly-defined soil moisture isolines. This new Transformed Red-NIR (TRN) model was compared with the conventional Red-NIR (CRN) model using data from Salman Farsi sugarcane field located in Khozestan province in southwestern of Iran. Twelve Landsat-8 satellite images were used during the sugarcane growing season. For validation of the remotely sensed data, ground reference soil moisture was measured at 22 locations at five different depths. Results of the proposed new method significantly improved accuracy of the Red-NIR approach to remote sensing of soil moisture.

The present study was conducted to investigate the effect of cultivation on potassium forms and potassium adsorption characteristics behavior in tobacco-growing and adjacent virgin soils in Northwest of Iran. Soil potassium forms were determined in 29 tobacco-growing soils and in 29 adjacent virgin soils. Soil potassium quantity-intensity relations (Q/I) were constructed by equilibrating and shaking 2.5 g soil with 25 ml of 0.01 mM CaCl2. The results indicated that the mean of exchangeable potassium (Kex) and the initial equilibrium concentration of solution potassium (EKC) values in tobacco-growing soils were significantly (p≤0.01) lower than those in the adjacent virgin soils and decreased 28% and 27 %, respectively. Thus, in tobacco-growing soils and their adjacent virgin soils, the mean of Kex were 197 and 273 mg kg-1, and the mean of EKC were 7.9 and 10.8 mg L-1, respectively. There was a significant correlation between solution potassium (Kso) and Kex (r=0.418*) as well as between Kex and clay (r= 0.577**) in tobacco-growing soils indicating depletion of Kex  in the studied soils. The mean of potassium activity ratio at equilibrium (AReK) and the energy of exchange potassium (EK) values in tobacco-growing soils were significantly (p≤0.001) lower than those in the adjacent virgin soils and decreased 36 and 11 %, respectively. In tobacco-growing soils and their adjacent virgin soils, the mean of AReK were 0.004 and 0.0063 mol L-1and the mean of EK were -3407 and -3055 cal mol-1, respectively. Because of exchangeable potassium depletion in the studied soils, potassium fertilizer management is needed to be practiced for sustainable production of tobacco in Northwest of Iran.

In this paper, subsurface flow profiles through coarse porous media have been simulated using a 3-D numerical model with and without surface discharge and their results have been compared with experimental data as well as with analytical solutions. SEEP/3D model, which is based on the finite element method, was used to simulate subsurface flow. The experimental model was consisted of coarse porous media with 6.4 m in length, 0.8 m in width and 1 m in height. The experiments were performed for different boundary conditions with two bed slopes of 4 and 20.3 %. The simulated data of watertableprofiles and seepage discharges were compared with those corresponding experimental data. In no recharge conditions with 4% slope, the numerical data were compared with both experimental and analytical dataindicating that the numerical results underestimated the watertable profilesas compared to the experimental ones. The results was better for the 20.3%-slope. In surface recharge condition, the numerical results only compared with analytical solution of Bear (1972), and the results indicated underestimation as compared to the experimental data.

Lack of oxygen and high salinity are factors that limit the biodegradation of the hydrocarbon. The electron accepters such as nitrate and salt tolerant bacteria can be used to increase the biodegradation rate in saline environment with low level of oxygen. In this paper, BTEX biodegradation by Bacillus thuringiensis andBacillus sp. is investigated in microaerophilic and saline environment under nitrate reducing condition. Firstly, the ability of the above- mentioned bacteria in BTEX biodegradation was confirmed. Then, the effect of Nitrate, BTEX concentration, salinity and cell mass on BTEX degradation was studied using Taguchi method and design expert software. The results of this study showed the ability of the Bacillus thuringiensis andBacillus sp. on BTEX degradation. For 200 mg/L BTEX concentration, the high efficiency of degradation by Bacillus thuringiensis andBacillus sp. could be achieved in optimum conditions; Nitrate Concentration (200 mg/L), salinity (1 and 5 %) and cell mass (1and 5×107 cell/ml) respectively.

The water movement in the aquifer is studied using the basic equations of flow, i.e. Darcy, continuity and mass survival equations, which are differently analyzed in the case of confined and unconfined aquifers. In these equations, hydrodynamic coefficients and other characteristics of the aquifer are used. Therefore, the determination of hydrodynamic coefficients of aquifer is necessary for groundwater studies. The most important characteristics of the aquifer i.e. hydrodynamic coefficients can be determined across the aquifer using modeling. If the aquifer model is properly provided, it can be a useful tool for better recognition of aquifer characteristics and also predicting the impact of different management plans on the water resources of the region. In this study, groundwater modeling was performed to determine the hydrodynamic coefficients in the unconfined aquifer of Kermanshah plain using GMS 7.1 software. The results showed that the amount of hydraulic conductivity in the Kermanshah plain aquifer varies from 0.1 to 30 meter per day and the amount of specific yield varies from 0.02 to 0.4. The amounts of computed water table by the model and the observed water table in the piezometers have high correlation and the root mean square error value is always less than one, which indicates the acceptable accuracy of the model for simulating the aquifer status.

Due to growing population and the major role of wheat in producing energy and protein for population, there is a need for new approach in farm management. This approach can help agricultural producers to identify changes in the farm and manage them in order to increase crop yield and productivity. The purpose of this study was to investigate the effect of different levels and sources of silicon application on the dry-matter production, concentration and nutrients uptake by seven wheat cultivars in the greenhouse research station of the Soil Sciences Department of the University of Tehran. This study was conducted in a completely randomized design with a factorial arrangement with two factors including silicon at six levels (control, potassium silicate with application levels of 200, 400 and 1000 Mg of silicon from the potassium silicate source per kilogram of soil, and silicon nanoparticles with application levels of 50 and 100 mg kg-1 soil) and wheat cultivars (Gonbad, Shirodi, Shiraz, Mahdavi, Marvdasht, Bahar and Parsi) with three replications. The results showed that the application of silicon in various levels and sources, wheat cultivars and their interaction on potassium concentration in shoot and the total amount of phosphorus and potassium in the shoot were significant (p≤0.01). Also, the concentration of silicon and potassium in the shoot of different wheat varieties were the highest in the case of application of silicon nanoparticles at different levels of potassium-silicate which ranged from 0.14-0.32 and 0.16-0.76%, respectively. The average total amounts of silicon, phosphorus and potassium uptake by the shoot also increased by increasing silica-potassium application which ranged from 0.12-5.08, 0.43-1.16 and 8.7-14.2 %, respectively. Therefore, considering the role of silicon in the nutrients uptake, its use, along with the planting of higher-uptake cultivars, could help to improve wheat growth.

In this paper with analyzing various geostatistical methods in three different scenarios, the influence of zonal classification and rainfall extrapolation on increasing accuracy of the proposed methods for daily rainfall in Karun basin has been analyzed. In the first scenario, only various geostatistical methods including weighting moving average, Kriging, Co-Kriging and TPSS were analyzed. In the second scenario, the study area was divided into homogeneous regions based on cluster method and the accuracy of the selected models were analyzed within each region. In the third scenario, some hypothetical stations were considered in elevation points without real observations, and then, the accuracy of geostatistical method with considering extrapolation technique was analyzed. Analyzing the related Variogram well demonstrated a geometric anisotropy, while this problem was solved up when an all-round variogram was applied. In the first scenario, the mean absolute errors and the mean bias errors were varied in the range of 14.7-36 mm and -1.5-4.5 mm, respectively. In this scenario, the Co-kriging method had the lowest estimation error due to the positive effect of the considered auxiliary variable on increasing variogram "range of influence". Although, the interpolation of daily rainfall data, after zonal classification, had no positive impact on decreasing of estimation error, but the weighting moving average and TPSS methods with the powers of 3-5 were the Exceptions. In addition, the estimation accuracy increased up to 16%, and the estimation bias reduced up to 10%, when precipitation was extrapolated in elevations with no rain gauges. Under this scenario, the maximum threshold of error variance reduced by 45% (from 7.8 mm to 4.8 mm). Based on the results, integrating extrapolation into the Co-Kriging method with considering elevation as an auxiliary variable results the best estimation when assessing the spatial variation of daily rainfall.

Pyrolysis of feedstocks and producing biochar is a suitable technique for agricultural wastes management, carbon sequestration and soil amelioration. The study of structural and physicochemical properties of biochars, which are strongly dependent on the type of feedstock and pyrolysis temperature, is very important to identify the suitable application of biochar in the soil. The objective of this research was to investigate the properties changes of biochars derived from corn residue and sugarcane bagasse under different pyrolysis temperatures. This study was carried out under laboratory conditions based on a randomized complete design with eight treatments of corn residue, sugarcane bagasse and their biochars and in three replications. Biochars were produced at 200, 350 and 500˚C pyrolysis temperatures under slow pyrolysis conditions. Results indicated that increasing pyrolysis temperature from 200 to 500˚C, in corn residue and sugarcane bagasse treatments, decreased the yield (29.24 and 23.6% respectively), volatile matter (29.8 and 32.5%), cation exchange capacity (32.5 and 29.8%) and the ratios of C/N, H/C and O/C while led to increase the ash content of corn residue and sugarcane bagasse biochars (20.3 and 42.3% respectively), fixed carbon (23.2 and 14.7%), pH, EC, aromatic compounds and nutrients concentration. Concentration of nitrogen, phosphorus, potassium were greater in the corn residue than in the sugarcane bagasse treatments, but the C/N ratio were greater in the sugarcane bagasse treatments. Based on the results of this study, it could be concluded that biochars produced at 500˚C temperature can be more effective in carbon sequestration in the soil, whereas biochars produced at 200 and 350˚C temperatures are more suitable for improving soil fertility.

This study was carried out to investigate the effect of different levels of magnetic intensity (0, 0.2, 0.3 and 0.4 tesla) and different concentrations of nutrient solusion (0.25, 0.50, 0.75 and 1 unit of Hogland) on phytochemical and morphological changes of Physalis, as one of the high valuable species of medicinal plants. The results showed that the effect of the combined treatments on all phytochemical properties (with the except of antioxidant activity factor), as well as all morphological traits, was significant at 1% level. The maximum significant and positive effect on phytochemical factors improving chlorophyll b characteristic 15 times was obtained under 0.4 tesla magnetic intensity and 50% Hoagland concentration. Also, the most significant positive effect on morphological factors improving fruit weight by 2.5 times was obtained under 0.3 tesla magnetic intensity and 0.75 Hoagland concentration. In general, the application of magnetic water and nutrient solution concentration is suggested to be considered in Physalis production plannings.

Powder sulfur is the most common used substance for improvement of calcareous soils particularly their pH while its efficiency in the soil is highly depend on its oxidation condition. The Objective of this research is to evaluate the efficiency of various amounts of sulfur to improve calcareous soils in presence of sulfur-oxidizer bacteria. Hence, 15 soil columns containing a calcareous soil including four sulfur treatments labeled S(0.125), S(0.250), S(0.375) and S(0.500) and a control treatment with lack of sulfur, each with three replications were manufactured and inoculated using Thiobacillus thioparus and then brought under leaching once a two weeks for six months. The results showed that the leakage of sulfate caused by sulfur oxidation was intensified for the temperatures above 25°C and reached a maximum in 30°C. Moreover, statistical analysis among sulfur treated columns approved presence of positive significant relationships between temperature and sulfate leakage (α= 0.01) from one hand, and negative significant relationships between temperature and pH (α= 0.01) on the other hand.