Journal of Water and Soil Science
Year:2011 | Volume:14 | Issue:54|Papers Count:18

Precision in design of sprinkler irrigation systems and their proper management are very important for both development and also improvement of those systems. Therefore, the main objective of this study was to evaluate the design and management of the solid-set sprinkler systems in Dehgolan plain located in Kurdistan province. For this purpose, 10 solid-set sprinkler systems were selected randomly and a few performance parameters such as: Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ) and application efficiency of low-quarter (AELQ) were estimated. The results of investigation showed the mean values of 66, 50.6, 44.8 and 43.8%, for the above mentioned parameters, respectively. Also, the results of investigation showed both low PELQ values and water distribution uniformity of those evaluated systems compared to the recommended values by Merriam and Keller (1978). Moreover, due to deficit irrigation, except for one evaluated system, in all other systems, AELQ values were equal to PELQ. The results of our investigation also showed that non-suitable design and implementation of the evaluated systems were among the most important reasons for low values of PELQ, because of non-suitable operating pressure. The most important reasons for low water distribution uniformity were the simultaneous use of many sprinklers and also performance of different sprinklers models in a system. Finally, the results of our investigation showed poor operation for the evaluated systems in many cases.

Direct measurement of discharge in rivers is time-consuming and costly, and sometimes, impossible under flood conditions because of the high speed of water, its transitory nature, and the existence of different floaters along the water. Therefore, the discharge-stage relation, known as Discharge Rating Curve is used. Moreover, to design hydraulic constructions, the maximum flood discharge and its maximum height are required. Therefore, to calculate the flood discharges, one should extend the discharge rating curve by using appropriate methods. In this study, in order to determine the best method for the extension of discharge-stage curve, and to estimate the corresponding discharge with high stages, the logarithmic method, the Manning method, the Chezy method, and the Area-Velocity method in 13 hydrometric stations at the Karkheh watershed in Lorestan province were compared. Data measured at each station were gathered for a ten-year statistical period. Results of calculating the Root Mean Square Error (RMSE) and the Mean Bias Error (MBE) for each method showed that the logarithmic method was more accurate than other methods, and it was more appropriate for the extension of the curve at the low average discharge stations. The Area-Velocity method, after the logarithmic method, especially at the stations with higher average discharge showed good results. The Manning and Chezy methods showed the least accuracy.

This paper presents the results of an analytical and experimental study on the characteristics of hydraulic jump in a triangular channel. The analytical consideration is based on the momentum conservation law for the upstream and downstream sections of the jump. The experiments were carried out in a triangular channel of glass side walls with the vertex angle of 94.4o. A wide range of discharge and inflow Froude number were used in the experiments for two different opening heights of the upstream sluice gate. The main characteristics of the jump such as the sequent depth ratio, relative energy dissipation and water surface profile were investigated and the results were compared with those of the rectangular sections. The results showed that the triangular section is more efficient to dissipate the inflow energy. The efficiency of jump in a triangular channel is about 12% more than a rectangular channel for the same condition. As a result, hydraulic jump in a triangular channel needs a smaller tail water depth for a given inflow jet height and Froude number. Also, empirical relations and graphs are presented to determine the characteristics of the jump in triangular sections.

Channel lining is essential to increase resistance against scour, reducing water losses and as a result increase water conveyance efficiency. Since the canal lining has significant costs, selection of type of lining must be made with great care and with considering engineering properties. One of the conventional lining for water conveyance cannel is concrete lining. Because of advantages of concrete lining including durability (about 40 years) and low maintenance costs, this type of lining is the best option in many regions, however the construction expenses is high. So far many researches have been published about the types and the durability of concretes containing synthetic pozzolans. Due to high production of wheat in our country, nano particles of wheat ash sheath (NPWAS) were used. In this study the mechanical properties of concrete (compressive strength, tensile strength and durability) incorporating nano-particles of wheat ash sheath were investigated. The results showed that the compressive and tensile strength of samples incorporating 20 percent of NPWAS has not statistically significant difference (P<0.05) with the values of tensile and compressive strength of control samples. Therefore, the optimum replacement percentage of NPWAS was 20 percent by weight of cement. Moreover, results of durability of concrete samples showed that concrete containing 20 percent NPWAS were more durable than control samples in the magnesium sulfate solution. NPWAS with having 90.56 percent of silicon dioxide, high pozzolanic activity and ability to perform substantial chemical reaction with calcium hydroxide would decrease porosity and increase resistance of concrete.

The temporal and spatial vegetation dynamics is highly dependent on many different environmental and biophysical factors. Among these, climate is one of the most important factors that influence the growth and condition of vegetation. Of the abiotic factors affecting the geographic distribution of vegetation type, climate is probably the most important. Ecological research has traditionally aimed to generalize vegetation types that are assumed to be homogenous. Most of climatic classifications related to bioclimate are focused on limited climatic factors such as temperatue, precipitation and combination of them. As climate is a compound phenomena using limited factors cannot show the climate of a region, and as a result most climatic factors must be considered in bioclimatic classification. Therefore, a climatic study using various climatic factors could reveal the effective factors in distribution of vegetation. In order to determine bioclimatic zones in Chahar-Mahal & Bakhtiari province using multivariate statistical method, 71 climatic variables, which were more important in plant ecological conditions, were selected and evaluated by the factor analysis. The factor analysis revealed that the first three factors which explain 91.8% of total variance among the selected variables were temperature, precipitation, and radiation. According to results and using hierarchical cluster analysis in Ward’s method, bioclimatic classification in Chahar-Mahal province was carried out and 5 bioclimatic zones were found. In addition, Chahar-Mahal province was classified by 4 traditional climatic classification methods (Koppen, Gaussen, Emberger and De Martonne) and those classes were compared to climatic classes obtained by multivariate statistical method. The latter comparison was suggestive of the fact that multivariate statistical method provides a more appropriate classification in comparison to the traditional methods, specially because more dominant vegetation species could be defined for each of the newly described climatic classes. Furthermore, dominant species were determined for each climatic region.

Although the crucial function of earthworms in improvement of soil physical properties is well -know, but very little is known of the interactive influence of earthworms and organic materials on soil properties such as soil aggregate stability, particularly in arid and semi-arid soils. The low organic matter content and the significant role of earthworms in improving physical properties of arid and semi-arid soils necessitate studying the interactive effects of organic materials and earthworms. Thus, the main objective of this study was to identify the interactive effects of anecic earthworm (Lumbricus terrestris L.) and various organic residues (including alfalfa, compost, mixture of alfalfa and compost and cow dung) on soil aggregate stability expressed as the Mean Weight Diameter (MWD), Geometric Mean Diameter (GMD) and Aggregation Ratio (AR), and furthermore soil Ca and Mg contents. The experiment consisted of a 2×5 factorial treatment organized in a completely randomized design with four replications under controlled greenhouse conditions, lasted for 150 days. Results showed that earthworm inoculation and organic materials addition alone increased significantly all the indices of soil aggregation and aggregate stability, and Ca and Mg contents. However, the combined use of earthworms and organic residues resulted in more stable aggregates. Results indicated that earthworm inoculation in the presence of organic materials resulted in 39, 58, 2, 67, 43 and 74% increases, respectively in MWD, AR, GMD, Ca, Mg and macroaggregates whereas microaggregates were reduced by 13.5% in earthworm-worked soils. We observed a significant relationship (R2=0.945) between soil Ca content and MWD, demonstrating that earthworms apparently excrete calcite that helps bonding clay particles and soil organic matter via cationic (Ca+2) bridging. In summary, results of this study show that the simultaneous applications of anecic earthworms and organic materials may considerably help in improving the structure of arid and semi-arid soils with low carbon level.

In this study, the effects of enhancing synthetic chelators (HEDTA, EGTA) and low molecular weight organic acids (LMWOA) such as citric acid were compared on cadmium (Cd) solution in soils that were artificially contaminated. Also Cd phytoextraction capability by radish (Raphanus Sativus L.) was studied. The experiment was laid out in a randomized complete factorial design where each treatment was replicated three times. Concentration treatments of cadmium using CdCl2 were 0(control), 5, 20, 60 and 100 mg Cd kg-1. After complete growth of plants, 6, 20 and 20 mMkg-1 soil HEDTA, EGTA and Citric Acid were added per pot, keeping a control without any chelator application. In order to determine cadmium concentration ten days after adding chelates, samples were taken from the plants and soil of pots. The results showed that in all treatments the concentration of soluble Cd in soil was higher than the control. Also the results showed that synthetic chelators as compared with LMWOA (Citric Acid) have increased the solution remarkably. Among the other chelates, HEDTA had significant effects on Cd solution. In the current study, Cd concentration in shoot and root of (Raphanus Sativus L.) was increased with enhancement of Cd concentration in soil. Cd concentrations in shoots of radish were higher than those in roots. This could refer to higher bioavailability and solubility of Cd. In the current study, in all the treatments with HEDTA Cd concentrations in shoot and root of (Raphanus Sativus L.) were increased as compared with other chelates.

The addition of organic and inorganic substrates to calcareous soils low in organic matter and nitrogen contents may change soil microbial biomass and activity. In order to investigate the effect of chemical and organic fertilizers on soil CO2 production and microbial biomass C, a field experiment was conducted under maize cultivation. The experimental design was split-plot arranged in randomized complete blocks with 7 treatments including 3.8, 7.6 and 11.5 ton ha-1 broiler litter and 100, 200 and 300 kg nitrogen ha-1 from urea and a control with 4 replications. The results showed that fertilizer, manure and sampling day had a significant effect (P<0.05) on soil CO2 fluxes. Mean soil CO2 emissions increased from 21.8 g C m-2 soil in control treatments to 24.1 in the second level of broiler litter. Furthermore, the CO2 fluxes in broiler litter treatments were significantly greater than those in urea-treated plots. Similar to CO2 fluxes, the amount of soil microbial biomass C was also affected significantly (P<0.05) by fertilizer and manure applications. Soil microbial biomass C was 28% higher in broiler litter-amended plots than that in urea-amended plots. In contrast, the microbial metabolic quotient (qCO2) in urea-treated soils was 10% higher than that in broiler litter-treated soils. In conclusion, broiler litter and urea fertilizer improved biological properties in this calcareous soil, but broiler litter, especially the highest litter loading, was more effective than urea fertilizer.

Due to low availability of zinc and copper in calcareous soils and the antagonism of these nutrients with each other, the study of their effects on growth and chemical composition of rice seems to have great importance. Also, the relations among different chemical forms of Zn and Cu and plant responses are very important, which can be used in investigation of antagonisms of these nutrients as well. Therefore, by application of different levels of Zn and Cu, their effects on plant growth and nutrient concentration in the plant were studied and different forms of these nutrients in soil were determined. Results showed that zinc application increased plant growth, Zn concentration and total uptake, but decreased Cu concentration in the plant. However, copper application showed no significant effects on the plant growth, but increased Cu concentration and total uptake and decreased Zn concentration in the plant. Also, the results showed an increase in carbonatic, adsorbed and exchangeable Zn forms and exchangeable Cu form by Zn application. Carbonatic form of zinc has maximum effects on concentration and total uptake of this element in the plant. Copper application increased carbonatic and organic forms of this nutrient in soil, and there was maximum correlation between organic form of Cu and its concentration and uptake in the plant.

This study was conducted to investigate nutritional status and some quality aspects of greenhouse cucumber in Qom province. After selecting 20 greenhouses, concentrations of macro- and micronutrients as well as lead (Pb) and cadmium (Cd) in soil and plant were measured. In addition, some fruit quality attributes were determined. Phosphorus (P) and potassium (K) concentrations in soils were much higher than their critical levels. The mean concentrations of soil DTPA-extractable iron (Fe), copper (Cu), and manganese (Mn) were 12.0, 1.98, and 14.5, respectively. The mean concentration of calcium (Ca) in cucumber leaf was high while in fruit was lower compared to its sufficiency level. Most fruit samples were deficient in K, Fe, Zn, Cu, and Mn. The mean nitrate (336 mg kg-1) and Pb (0.34 mg kg-1) concentrations in cucumber fruits were higher than their acceptable levels. Ascorbic acid concentration of fruits showed positive correlation with Fe concentration. Also, fruit Mg concentration had a positive correlation with the total dissolved solids and negative correlation with fruit moisture content. The results indicated that improper nutrition management in Qom cucumber greenhouses has caused micronutrients deficiencies and high nitrate and Pb concentration, which are important to consumers' health.

Geologic and pedologic controls are the main factors determining the distribution of elements in natural soil environments. In order to assess the role of these factors in the content and distribution of major elements of soil, six parent materials including phyllite (Ph), tonalite (To), periditite (Pe), dolerite (Do), shale (Sh) and limestone (Li) were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material. Total content of Si, Al, Ca, Mg, Fe, Mn, K, Na, Ti and P of soil horizons were measured and compared to the geochemical and mineralogical composition of parent materials. Maximum concentrations of Fe2O3 and MgO were found in the soils derived from Pe and Do; however, these soils had low content of SiO2 and Al2O3, which is in conformity with the geochemical composition of the parent rocks. On the contrary, FeCBD content of these soils was lowest, indicating the low degree of soil development and, by the same fact, the importance of inheritance factor in soil Fe concentration. However, comparison of total Fe and FeCBD in Li1, Sh2 and To2 revealed that relative development of these pedons is higher than the others. Silicon depletion in Ph1, To2 and Sh2 pedons, relative to parent rocks, is higher than in Pe and Do pedons. However, this element is enriched in Li pedons. MnO content of Pe and Do pedons is governed by geogenic factors, while in Sh pedons, pedogenic factors, especially redox conditions, play the major role. Exchangeable forms of Ca and Na are determined by soil properties rather than by parent material type. Notwithstanding the redistribution of all major elements throughout pedons due to soil forming processes, the importance of inheritance factor in soil Si, Al, Mg, Fe, K, and Ti is higher than pedogenic factors.

The management and application of organic wastes in agricultural lands decreases environmental risks and increases utilization of these matters. The objective of this research was to investigate and compare the effect of polyacryl factory sewage sludge (PSS), municipal compost (MC) and cow manure (CM) on soil properties and on yield and growth of maize (single cross 704, Zea mays L.). The treatments were control (without any organic waste) and application of PSS, MC, and CM at two rates (15 and 45 t ha-1). This research was done in the research farm of Isfahan University of Technology (Lavark-Najafabad). The experimental design was a randomized, complete block with three replications. Treatments were incorporated into the soil before the maize planting (on 23 June 2008) and soil sampling was performed after 132 days (Simultaneously with maize harvesting). Application of the organic wastes resulted in significant increase soil organic matter (SOM), total nitrogen (TN) and saturated hydraulic conductivity (Ks) and significantly decreased bulk density. However, saturated hydraulic conductivity was decreased by application of PSS. Application of 15 and 45 t ha-1 of PSS reduced Ks more than 14% and 42%, respectively, compared with control; however, the reduction was significant only in the plots which received 45 t ha-1 of PSS compared with control. The results of plant yield and growth showed that leaf area index (LAI), plant length, biological yield, 1000 seed weight and seed yield increase due to the application of organic wastes.

The effect of phosphorus (P) (0, 25, and 50 mg kg-1 soil as Ca(H2PO4)2) and organic matter (OM) (0, and 2% w/w feedlot cattle manure) on P and zinc (Zn) distribution in different parts of wheat plant (Triticum aestivum L.) at various growth stages and its relationship with soil P and Zn were determined in greenhouse condition. In all pots, shoot P concentration decreased as plant growth proceeded. Phosphorus concentration of shoot and flag leaf decreased from 7th to 9th stage of growth, whereas that of spickle increased. Spickle P uptake and Zn uptake of stem, shoot, flag leaf, and spickle increased with proceeding of wheat growth. Phosphorus uptake of shoot increased from 3th to 9th growth stages, whereas P uptake of stem and flag leaf decreased from 7th to 9th growth stages. Soil P and Zn concentrations increased with application of P and OM and plant growth. The trend of P and Zn changes in shoot, stem and flag leaf was similar. It is, therefore, concluded that analyzing flag leaf for P and Zn concentrations be used for prediction of plant nutritional status of those nutrient elements in cases where such information is needed.