Soil science
F. Alizadehgan; M.A. Gholami; S. Shiukhy Soqanloo
Abstract
IntroductionIncreased agricultural activities, the occurrence of successive droughts, and limited freshwater resources, along with increasing population, have made a priority for the importance of protecting water resources in programs of developed and developing countries. Due to the climatic conditions ...
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IntroductionIncreased agricultural activities, the occurrence of successive droughts, and limited freshwater resources, along with increasing population, have made a priority for the importance of protecting water resources in programs of developed and developing countries. Due to the climatic conditions in Iran, which has a wide range of arid and semi-arid characteristics, facing the challenge of water resources crisis, is inevitable. Therefore, the use of wastewater is very important.Materials and MethodsThis research was conducted in the research farm of Sari University of Agricultural Sciences and Natural Resources (SANRU), which has a silty clay soil texture. The latitude and longitude of the region are 36º 40ʹ N and 53º 04ʹ E, respectively. Its height above sea level is 21 meters. According to Demarten classification, Sari city has a temperate humid climate. The long-term average temperature of Sari is 11.18 °C and the total long-term rainfall is 780 mm. In order to evaluate the wastewater effects on soil chemical characteristics, microelements concentrations, heavy metals accumulation and Maize yield (Single Cross 704), an experiment was carried out as factorial based on a completely randomized design with treatments included; Water source factor (wastewater (A1), well water (A2)), Irrigation (subsurface method (I1) and (drip method (I2)) with three replication in 2018-2019 under lycimetric conditions, at the Sari Agriculture and Natural Resources University (SANRU), Iran.Results and DiscussionAccording to this study results, the effect of type of irrigation source on soil electrical conductivity, soil microelements and heavy metals accumulation of the soil was significantly different (P ≤ 0.01). The highest soil electrical conductivity with a value of 1.8 dS.m-1 was observed in the conditions of using treated wastewater. The highest amount of total nitrogen, phosphorus and potassium were related to the source of treated wastewater with values of 0.086, 24.2 and 222.2 mg.kg-1, respectively. The results showed that the accumulation of soil Pb (0.07) and Cd (0.014 mg.kg-1) in irrigation with treated wastewater increased compare to the well water source by 0.05 and 0.010 mg.kg-1, respectively. Also, the effect of irrigation method and the interaction effect of source and method irrigation on soil chemical characteristics, microelements concentration and heavy metals accumulation were not significant. The use of wastewater by increasing soil stability improves soil physical condition, increases soil fertility, increases photosynthetic products, increases the efficiency of plant photosynthetic system and ultimately improves plant growth. The use of subsurface irrigation resulted in a 67% increase in grain yield and 28% increase in biomass productivity compared to the drip method. Adequate nutrients during the reproductive growth stage of the plant play an important role in grain growth. Therefore, it can be said that the nutrients in the wastewater have increased the grain yield compared to using the well water source. Because the wastewater contains nutrients and micronutrients such as; nitrogen, phosphorus, potassium, calcium, zinc and iron were relative to the well water source and increased maize grain yield. The results showed that the use of effluent compared to well water, caused the absorption of more heavy metals lead and cadmium in the grain, leaf and stem of maize. Due to the use of wastewater water source, the amount of Pb uptake among different parts of the maize, with values of 27.2, 22.5 and 20.5 mg / g, respectively, related to the grain, leaf and stem. However, the uptake of Cd in the grains, leaves and stems was 2.32, 1.35 and 2.01 mg / g, respectively. According to the results, the high concentration of heavy metals Pb and Cd due to the use of wastewater in the grain sector directly threatens human health. Also, the concentration of heavy metals Pb and Cd in the leaf and stem parts of corn, by endangering the health of livestock and poultry, indirectly affects human health.ConclusionThe results showed that irrigation with treated wastewater due to its richness in nutrients and microelements, improves soil fertility and creates favorable conditions by increasing soil organic matter and mineral for plant growth. Also, according to the permissible threshold values of the concentration of heavy metals Pb and Cd in plants, the accumulation of heavy metals Pb and Cd in the grain, stem and leaf of single cross 704 corn, will not be a problem for consumers. Optimal use of wastewater can increase soil fertility and the ability of plants to absorb nutrients from the soil and ultimately increase plant yield.
Z. Pashazadeh Laleh; H. Jafari; A.R. Vaezi Hir
Abstract
Introduction: The water is the major key in sustainable development, so it is necessary to be managed and conserved. The quality of surface water resources is mainly controlled by natural or geogenic factors including chemistry of recharge water, soil and geology processes, as well as the man-made contaminant. ...
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Introduction: The water is the major key in sustainable development, so it is necessary to be managed and conserved. The quality of surface water resources is mainly controlled by natural or geogenic factors including chemistry of recharge water, soil and geology processes, as well as the man-made contaminant. Qualitative indicators are used as effective managing tools in decision making programs. Water quality indices (WQI) are the simple and suitable tools to determine the quality statue of the water. In order to calculate the water quality index, many parameters are integrated in mathematical formula to represent the quality condition of the water with a number which classifies the quality in the scales of the weak to excellent. Many water quality indices were introduced by researchers and organizations around the world. Aji-Chay, one of the most important flowing rivers in East-Azerbaijan province, northwest of Iran, is passing through Tabriz plain in its way and finally ends to the Uremia lake. Regarding the focused industrial zones, agricultural field and urban areas in this plain, the river is highly vulnerable to pollution and quality degradation. So, this study was aimed to assess the Aji-chay River based on quality indicators, in order to helps its better management. Materials and Methods: In this research for assessing pollution of the Aji-Chay river using water quality indices, 16 sampling stations were located along the river and water samples were collected during wet (May 2016) and dry (September 2016) seasons. Electrical conductivity (EC), temperature, dissolved oxygen (DO) and pH were measured in the field and total dissolved solids (TDS), turbidity, major ions (Ca, Mg, Na, K, HCO3, Cl, SO4), nitrate (NO3), phosphate (PO4), biological oxygen demand (BOD), chemical oxygen demand (COD) and biological contaminants (fecal coliform) were determined in the laboratory. Quality indicators including the US national sanitary foundation water quality indices in the two forms of multiplicative (NSFWQIm) and additive (NSFWQIa) and Iranian surface water quality index (IRWQIsc) were used to assess the quality of the Aji-Chay river. Results and Discussion: Turbidity and Electrical conductivity (EC) is high at the upstream which is related to movement of the River in upper red formation (Miocene series) which enhances the chloride, sodium, calcium and sulfate. Arsenic concentrations are exceeding the drinking standards (0.01 ppm) across all samples mainly from a geogenic sources as well as discharge of wastewater in some areas. The elements Cd, Mn, Ni, Pb, Mo, Co, Zn, Fe and Al are mainly geogenic, whereas Cu, Ba and Cr are mostly originated from anthropogenic activities. Based on the results, river quality at the wet season is highly controlled by the main branch and Gomnab-Chay, but Mehran-rood plays the major role in downstream water quality at the dry season due to its higher discharge rate. The process was confirmed by Piper and Schoeller diagrams. Most of the parameters are increased in middle parts at the river where the concentrated sources of contaminates and discharge of wastewater increased the organic and biological constituents and nutrients especially in dry season. Assessing the river quality for agricultural uses based on modified Wilcox diagram shows except for Mehran-rood, the other samples are unsuitable for agriculture and the dry season quality is better than the wet season. Based on the results, increase in most parameters and so, pollution and quality degradation of the river are observed to the downstream. Assessing quality of the Aji-Chay river using US national sanitary foundation water quality indices in the two forms of multiplicative (NSFWQIm) and additive (NSFWQIa) and Iranian surface water quality index (IRWQIsc) confirmed the bad to very bad qualitative statue of the river in most stations especially in the middle parts of the Tabriz plain. The results revealed that quality degradation of Aji-Chay river is probably due to discharge of contaminants from municipal and industrial wastewaters (effluents), highlighting the need for managing actions to improve quality of this important river. Comparing the quality indices showed the priority of NSFWQIm (multiplicative form of US national sanitary foundation water quality indices) in quality classification and pollution assessment of the Aji-Chay river. Conclusion: Quality degradation of Aji-Chay river is probably due to discharge of contaminants from municipal and industrial wastewater effluents, indicating the need for managing actions to improve quality of this river. In this study priority of NSFWQIm (multiplicative form of US national sanitary foundation water quality indices) in quality classification and pollution assessment of the Aji-Chay river was confirmed.
Saman Hajinamaki; Hojat Emami; Amir Fotovat
Abstract
Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the ...
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Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the reuse of wastewater as a secondary source and replaces drinking water. The effects of irrigation with wastewater on physical, chemical and biological properties of soil have been studied by many researchers, which most of them are based on the direct use of untreated wastewater in agricultural land irrigation. In fact, a large amount of wastewater used in the agriculture is indirectly entered into the rivers, and used in the agriculture lands. Irrigation with wastewater may have effects on soil properties such as pH, EC, nutrient content, sodicity, pollutants and etc.
Materials and Methods: In order to determine the effect of irrigation by wastewater on soil properties in May 2015, several points of the Kashafrood River in the north of Mashhad were selected. The studied points were located between 59˚36ʹ- 59˚41ʹ E and 36˚19ʹ- 36˚22ʹ N geographical position. The wastewater is refined in Parkandabad station, and used for irrigation. The samples were taken from a depth of 0-30 cm in each point and three replications were regarded for them. Sampling distance was one kilometer from each other. In general, 15 points were irrigated with wastewater were selected. 12 physical, chemical and biological properties including pH, soil texture, bulk density (BD), dispersible clay (DC), mean weight diameter of aggregates (MWD), sodium adsorption ratio (SAR), organic carbon (OC), available phosphorous (P), available potassium (k), total nitrogen (TN), microbial biomass and base respiration (BR) were measured as a total data set (TDS). According to Liu and Chen the main component with an Eigen value greater than one using the PCA method were chosen as minimum data set (MDS). Within each PC, highly weighted properties were defined as those with absolute values within 10% of the highest weighted loading. When more than one variable was retained in a PC, each was considered important and was retained in the MDS if they were not correlated (r < 0.60). Among well-correlated variables within a PC, the variable having the highest correlation sum was selected for the MDS. Data analysis were performed using SPSS Statistics22 software.
Results and Discussion: The results showed that irrigation with wastewater increased biomass and BR, OC, SAR, K and stability index of soil structure. The parameters of K, TN, pH and MWD have been increased compared to the control, but were not statistically significant. Using PCA, five PCs were obtained, which PC1 and PC2 with Eigen value of 50.6 % were the most important components. The parameters of OC, SAR, TN, pH, BD, MWD, BR and K were chosen as MDS due to be changed as a result of irrigation with wastewater. Then, the correlations between these parameters in two groups of irrigated soils with wastewater and control were investigated. Organic carbon in both soil groups had the highest correlation with the SI. The SAR in both soil groups was negatively correlated with nitrogen and phosphorus. Nitrogen in irrigated soils with control was positively correlated with the SI and OC. The MWD was not correlated with any parameter. PH had shown positive correlation with microbial biomass and OC was positively correlated with BR, TN and SAR in soil controls. Potassium in the irrigated soils with wastewater had the negative and significant correlation with OC, SI, BD and MWD. Microbial respiration had a high positive correlation with SI, OC and TN in irrigated soils, which is due to carbon and nitrogen in the wastewater and causes an increase in its amount compared with the control.
Conclusion: The results showed that irrigation with wastewater caused a significant increase in parameters SI, SAR, P, BR, MBC and organic carbon in irrigated soil with wastewater and pH, MWD, TN and K had no a significant difference. On the other hand, the principal component analysis of the two groups of irrigated soils with wastewater and control had two distinct groups indicating that the irrigation with wastewater had a significant impact on the soil properties. According to the principal components analysis, eight parameters including OC, SAR, TN, MWD, BD, pH, BR and K were selected as the most important parameters to study the effects of irrigation by wastewater.
Mehrnaz Amini; Hamed Ebrahimian
Abstract
Introduction: Water scarcity is an important challenge worldwide, especially in arid and semi-arid regions. Water-scarce countries will have to rely more on the use of non-conventional water resources to partly alleviate water scarcity. The reuse of wastewater for irrigation is considered to be beneficial ...
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Introduction: Water scarcity is an important challenge worldwide, especially in arid and semi-arid regions. Water-scarce countries will have to rely more on the use of non-conventional water resources to partly alleviate water scarcity. The reuse of wastewater for irrigation is considered to be beneficial for crop production, and due to its nitrogen and phosphorus content, it can help to reduce the requirements for commercial fertilizers. However, under certain conditions, this type of water if not well managed, can have negative impacts on cultivated crops and soils, particularly on soil salinity and sodicity, and may pollute groundwater, as a result of high nitrogen concentration of most treated wastewater. Besides nitrogen (N) contamination of surface and ground waters has become a serious and global environmental problem. The risk of groundwater contamination by N depends largely on the N input to agricultural fields in the form of inorganic fertilizers and on its effective use of agricultural crops. Improvement of irrigation and nitrogen application management during the growing period can be achieved using mathematical models. The goal of this study was to assess the effects of irrigation with raw and treated wastewater by using the HYDRUS-1D model for simulation of water and nitrate transport in a maize field.
Materials and Methods: The experimental station of the College of Agriculture and Natural Resources, University of Tehran, was considered as a case study. The information of maize growing season in 2010, as well as raw and treated wastewater of Ekbatan housing complex was considered as a source of irrigation water for simulation of water and nutrient movements in the soil by HYDRUS-1D software package. HYDRUS-1D numerically solved the Richards equation for describing the variably-saturated water flow in a radially symmetric domain and the convection-dispersion equation for solute transport. The soil hydraulic properties were described using the van Genuchten-Mualem model. Since the direct measurement of soil hydraulic parameters in the field or laboratory is time consuming and costly, they were estimated using the ROSETTA model, using particle size and bulk density data determined on soil samples taken from depths of 0-20, 20-40, 40-60 cm.
Results and Discussion: The results showed that water contents increased after any irrigation event, and then decreased gradually during the following hours and days, until the next irrigation took place. Deeper depths showed smaller water content variations since root water uptake and soil evaporation were more pronounced at shallower depths. Simulated plant water uptake was estimated to be 80% of the water application, indicating the high irrigation efficiency of the system. Cumulative deep percolation (DP) values increased rapidly at around 43 days after planting. This is obtained due to higher irrigation water depth applied at irrigation events after this time because of rapid growth of maize crop that is occurring due to increase air temperature at this time. Simulated deep percolation reached 6.98 cm which is 13% of the total amount of water applied during the growing season. Simulation results showed that N leaching at 60 cm depth for about 7.61 and 2.64 kg N ha-1 for raw and treated wastewater, respectively. Nitrogen concentration for raw and treated wastewater decreased due to root nutrient uptake. The results also showed that the crop N uptake was 76.2% and 81.9% of total N input (TNI) during the growing season, while 19.4% and 14.5% of TNI was retained in the soil at the end of the season for raw and treated wastewater, respectively.
Conclusion: The HYDRUS-1D model was used to simulate the transport of N-NO3- under the raw and treated wastewater application in the soil. Simulation results provided detailed moisture and N regime, as well as bottom boundary flux for percolation and N leaching estimation. N leaching is closely correlated with vertical water flow. The N leaching distributions at the bottom of the soil profile (60 cm) are similar to the corresponding water flux distributions. The results also showed that the crop N uptake was 130 and 60 kg N ha-1 during the growing season for raw and treated wastewater, respectively. As the results showed wastewater can use as a source of N for crops and it can help to reduce the requirements for commercial fertilizers, and decrease their negative environmental impacts. It is suggested that the model parameters can be measured practically, in order to be used for model calibration and validation. Besides, the simulation can be done for a longer period of time to evaluate the effect of rainfall and different cultivations on solute transport.
M. Hajhashemkhani; M. Ghobadi Nia; Seyed Hassan Tabatabaei; A. Hosseinpour; S. Houshmand
Abstract
Recently, wastewater is one of the water resources for irrigation due to the scarcity of water resources. In this regard, using adsorbents such as zeolites is recommended to improve the characteristics of the wastewater. Although the results show that natural zeolite decrease amount of pollutions but ...
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Recently, wastewater is one of the water resources for irrigation due to the scarcity of water resources. In this regard, using adsorbents such as zeolites is recommended to improve the characteristics of the wastewater. Although the results show that natural zeolite decrease amount of pollutions but at the same time decreases the permeability of the soil, which could adversely affect the soil. This study was done in 2012 at the Shahrekord University, 27 PVC columns were used to study the effect of modified zeolite particles on permeability and quality of the wastewater. The experiment consisted of two factors the type of the microzeolite (natural zeolite, modified zeolite) and application procedure of the micro zeolite (mixed, layer) with three replications and in total had 7 treated. Injection of wastewater into the soil was through waterlogging and repeated fifteen times with a weekly frequency. Volume of wastewater used in each injection is equal "nv". In frequency injections of 1,3,5,7,11,15 infiltration was measured using Falling Heads. The results showed that treatment of modified zeolite included mixed, middle layer and layer on the surface had the highest infiltration rate respectively and treatment with natural zeolite included mixed, middle layer, layer on the surface had lowest infiltration rate. Further modified treatments decreased Ca effluent rate 111% with respect to natural Zeolite and therefore caused modified treatments to decrease SAR amount 45% with respect to control treatments and 132% with respect to natural zeolite.
A. Hassanoghli
Abstract
Produced sludge from wastewater treatment plants is a source of macro and micro nutrients and organic matters which is needed for agriculture. On the other hand, application of sludge with no criterion may cause some health risks and also, soil and surface water and ground water resources pollution may ...
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Produced sludge from wastewater treatment plants is a source of macro and micro nutrients and organic matters which is needed for agriculture. On the other hand, application of sludge with no criterion may cause some health risks and also, soil and surface water and ground water resources pollution may be followed. In this regards, the effect of different amounts of sewage sludge used as organic fertilizer in compare with chemical fertilizers on transport of minerals below the root zone and yield and yield components in soybean cultivation were studied. Therefore, 15 cylindrical plastic soil culomns with a height of 100 cm and 60 cm diameter were constructed and drainage PVC pipes with geotextile filter were installed for all of them. The sludge of Ekbatan housing complex wastewater treatment plant after processing and digestion was taken place and used. The culomns were filled by a Clay Loam textured soil and Soybean (Williams variety) was planted. Treatments include three levels of wastewater sludge fertilizer (10, 25 and 50 ton/ha), chemical fertilizers (150 kg/ha ammonium phosphate and 50 kg/ha urea) and control without using fertilizer in three replications. According to the results, the highest mean amount of nitrate in drainage water of culomns (base on split plot through time as statistical completely randomized design) was 57.17 mg/lit in the early season and treatment related to the use of sludge was 50 ton/ha. The lowest mean value of nitrate obtained from the control in the end of cultivation season and was 3.51 mg/lit. The most yield of Soybean was 277.85 gr grains per culomn which obtained from use of 50 ton/ha of manure sludge. The greatest weight of 1000 grains and the number of pods with values of 127.42 gr and 856 in number, measured in this treatment too. Application of 25 ton/ha sludge, chemical fertilizers and 10 ton/ha sludge were after it, respectively. So, the highest use of sewage sludge on soybean cultivation (at the rate of 50 ton/ha), transfer the highest amount of nitrate below the root zone and led to the best yield indicators
