نشریه آب و خاک
سال بیست و چهارم شماره 6 (پیاپی 14، بهمن و اسفند 1389)

One of the problems in design of irrigation structures is sedimentation control in the inlet to the irrigation networks. Water quality for agriculture requires that the sediments be controlled and reduced to the permissible limit at their entrance point to the turnouts and irrigation networks. This is possible by constructing a sedimentation basin. The bigger the basin, the best the retardation of the sediments, but the expenses are higher too. Different mathematical models are developed for sedimentation basins. Most of these models show the relationship between efficiency and effective parameters by mathematical formulas. In this research, a computer software for design of settling basins was designed in which design parameters (length, width, depth, slope and water velocity in the basin) are determined such that the basin has the specified technical characteristics and it is built with minimum cost. In this respect, operations research and a lexicographic enumeration algorithm is used. Application of this software for evaluation of construction costs of sedimentation basins in Nekouabad diversion dam Zayandehrud irrigation networks at Isfahan) showed that efficiency of these basins is 50.6% and 46.5%. If these basins were built under optimum design, about 18% and 6% would have been saved in their construction costs, respectively.

In order to study of magnetic field and nanosilver effects on fodder maize in comparison to micronutrients fertilizers, an experiment was conducted at research farm of Razavi Research and Technology Institute in the year 2007. This experiment was done with 7 treatments based on randomized complete block design with four replications. Treatments were including (T1) magnetic field and silver nano particles + Kemira fertilizer (T2) magnetic field and silver nano particles + Humax fertilizer (T3) magnetic field and silver nano particles (T4) Kemira fertilizer (T5) Librel fertilizer (T6) Humax fertilizer (T7) control (NPK). Results showed that fresh yield was the highest in (T3) and T4 treatments. These treatments increased the maize fresh yield 35 and 17.5 percent in comparison to control respectinely. Dry matter yield of exposed plants to magnetic field and silver nano particles was more than other treatments significantly. There was not significant effect on fresh weight of maize ear. Magnetic field and silver nano particles treatments (T3 and T1) showed the greatest ear percentage in plant and the lowest found in T7 and T5 treatments. It is seems that in T3 treatment, depletion of Ca, N and P of soil was greater than other treatments. Exposure to magnetic field and silver nano particles enhanced the crude protein and decreased ADF in silage resulting in increasing silage quality.

Study of turbidity current hydrodynamics plays an important role in increasing the economical life of dams though reduction in sediment accumulation. In the present experimental study, the effect of entrance densimetric Froude number of turbidity current in sub and super critical conditions (Fr =0.6-3.5) have been tested through effect of channel slope and change related to opening height of entrance gate on vertical distribution of flow velocity and current's thickness under two dimensional flow conditions. The experiments were run in a 12 m-long by 0.2 m-wide by 0.5 m-high channel. Kaolin with the specific gravity of 2.65 and the mean particle diameter, D50, equal to 4.5 μm, was used as the cohesive suspended material. The results show that due to increasing in Froude number of entrance flow, the thickness of the turbidity current was increased while the layer-averaged velocity was decreased in the longitudinal direction. When the inlet densimetric Froude number reaches 0.7, the turbidity current tends to reach to a stable condition. Also the results show that the equivalent height of average velocity is about 0.8 times of the depth-averaged thickness of the current.

ICSSDOM is a mathematical synthetic model that was written with fortran77 and in which used SA simulation annealing algorithm like an internal loop in basic structure of ICSS hydrodynamic simulation model. This model presented by Mohseni Movahed in 1381. This model is able assess current performance and present optimal operation considering downstream requirement of turnout in real conditions and actual constrains of canal system. For performance optimization of irrigation, canals must be chosen a complete spectrum of indicators and optimized them in an objective function with utilization of optimization method. In this model, necessary actions are considered in order to appoint the relative value of indicators and also is noticed to it’s effectiveness in optimization process with sensitivity analysis. Another problem created after choosing appropriate indicators, is the lack of a standard and quantitative method for appointing their relative value. Using model, Mohseni Movahed (1381), mohseni (1384) and norozpour (1387) have assessed E1R1, E1R5 and E1L4 canals of DEZ networks respectively. In these researches, the most appropriate weighting coefficient of indicators is appointed to performance optimization of irrigation canals and applied method for mentioned coefficient is an origin basic mathematical and logical process, which doesn’t depend on any professional judgment. Although, hydraulic conditions in these canals are different, they show similar results. According to the results in all three cases, while the weighting coefficient of indicators is noticed as a direct proportion of difference between ideal and presented performance, the improvement percent is better than other conditions. The other important and new results of this research are such as: Determination of the suitable composition of SA optimization algorithm parameters and presentation a method and general vision in order to appoint the appropriate extent of Kdiv parameter relative to length of random steps in SA optimization algorithm. These results that earn after different and spreading testes of sensitivity analysis can summarize volume of testes and also can be applied as a confident criterion in future researches.

Soil salinity in huge parts of the world, especially in arid and semi-arid regions, is a factor limiting growth of plant and other organisms. Earthworm can be considered as an indicator of soil quality in agroecosystems, because of a positive correlation between earthworm abundance and the productivity of cropped plants. The main objective of this study was to realize the interaction between soil salinity and organic amendments on the growth and populations of anecic earthworm (Lumbricus terrestris L.) under controlled greenhouse conditions. The experiment was a 4×4 factorial consisting of three levels of salinity (2, 4 and 8 dSm-1) obtained using NaCl (plus a control) and three organic amendments (alfalfa and corn residues, cow manure and control) arranged in a completely randomized design replicated three times. The experiment lasted 15 weeks. Results showed that increasing soil salinity caused a significant reduction (P ≤ 0.001) in all the earthworm's growth indices. The increase in salinity from 0.49 dS m-1 (control) to 8 dS m-1 reduced the number of earthworms (32%), fresh weight of worms (54%), dry weight of worms (54%), worms length (25%) and the number of cocoon (35%), suggesting the harmful effect of salinity on earthworms growth. The application of organic amendments has, to some extent, alleviated salinity effects on earthworms, and resulted in increases in earthworm growth rates at all salinity levels. Soils amended with alfalfa residues showed the highest alleviating outcomes. In summary, salinity reduced the growth and activity of earthworms L. terrestris and the added organic materials, however, lowered the detrimental effects of salinity on earthworms in the studied soil.

Quantitative investigation of effects of range management treatments on different soil and water components in rangeland ecosystems has been rarely taken into account. In the present research, the Kodir Summer Rangeland in the Southeast Nowshahr in Mazandaran Province was selected for studying effects of open grazing and exclosure managements on infiltration, runoff and microrelief. Experimental plots in dimension of 0.5×0.5 meters were applied in order to estimate runoff and subjected to rainfall intensity of 1.6 mm.min-1. The infiltration rate was calculated for each plot as the difference between the applied rainfall to and the runoff collected from each plot. The microrelief was also measured by using a wooden ruler graded in 10 cm steps and adjustable to the plot edges. The results were then compared on storm basis with the help of Tukey test. The results showed that there was a significant difference in infiltration, runoff and microrelief in two study treatments at the confidence level beyond 95%. The amount of total infiltration, runoff and microrelief in open grazing treatment were almost 0.97, 1.48 and 1.50 times to those recorded for short time exclosure treatment, respectively.

The present study was carried out for developing and evaluating of the optimization model of cropping pattern in irrigation networks using analytical hierarchy process (AHP). The model was programmed into two sub-models. The objective of the first sub-model was ranking of crop appropriately, and the objective of the second sub-model was ranking of cropping area of each crop. Ten criteria, affecting crop type suitability, and nine criteria, affecting cropping area, were analyzed. The weight of criteria was determined base on the field investigation and the results of 30 completed questionnaires by local irrigation expert and farmers. The proposed model was run and evaluated in Varamin irrigation network. The evaluations showed that water volume and evapotranspiration criteria are more important than others in the determination of crop suitability. Also, global decisions on agricultural sector and water availability are the most important parameters in selecting cropping area. The results indicated that the AHP model has determined the crop type and cropping area ranks with high accuracy. Hence, the model may be recommended as a practical tool in evaluation of quantitative and qualitative effective factors of cropping pattern and in determination of crop type and cropping area in irrigation networks.

Shortage and improper distribution of rainfall in tea growing period are important growth limiting factors in tea fields in Northern part of Iran. If there is not any other limited factors, supplemental irrigation by sprinkler can increase tea yield. This study was carried out in order to investigate the optimum sprinkler irrigation interval on yield and water use efficiency of tea. The experiment was conducted on a CRBD with three replications during tea planting period of 2002-04 in Fouman tea research station. The irrigation treatments were 4, 8, 12 and 16 day irrigation intervals along with rainfed treatment as control. Results showed that control and 4 day interval treatment with 1483 and 3443 kg/ha had the lowest and highest yield respectively, and 8, 12 and 16 day irrigation intervals were in next grade, respectively. In term of water use efficiency, control and 4 day treatment in dry period with 0.34 & 0.67 kg (made tea)/m3 of used water had the maximum and the minimum water use efficiency. Irrigation water use efficiency in growing period for 4, 8, 12 and 16 day treatments were 0.66, 0.55, 0.48 and 0.36 kg/m3, respectively. Since very short period of dry season in the last year of the experience(2004), no significant difference was observed in yield.

Enhancing phytoextraction with aminopolycarboxylic acids (APCAs) associated with fast growing and metal tolerant plants species has been proposed for the clean-up of heavy metal contaminated soils. The objectives of this study were to assess the efficiency of EDTA and NTA for desorbing Pb from soil and to compare their effects for enhancing of Pb extraction with Land Cress (Barbara verna). The experimental factors were including 0, 100 and 800 mg Pb kg-1 soil, EDTA and NTA (0, 5 and 10 mmol kg-1 soil). The results indicated that EDTA was much more efficient for enhancing root to shoot Pb translocation. In 800 mg Pb kg-1 soil, as a result of 10 mmol EDTA kg-1 soil, a value of 1075 mg Pb kg-1 DW shoot was obtained. The soils treated with EDTA showed higher values of soluble Pb concentration than NTA and no chelate. Also, MLPI was higher (0.87) in presence of 5 mm EDTA kg-1 concentration. In high concentrations of Pb and APCAs, both EDTA and NTA caused acute symptoms on leaves which showed wilting, necrotic areas and curling of borders. Finally, Land Cress due to high lead resistance can be introduced as a Pb hyperaccumulator to chelate-induced phytoextraction technology.

Spatial prediction of soil organic carbon is a crucial proxy to manage and conserve natural resources, monitoring CO2 and preventing soil erosion strategies within the landscape, regional, and global scale. The objectives of this study was to evaluate capability of artificial neural network and multivariate linear regression models in order to predict soil organic carbon using terrain attributes. A study area of 24 km2 in hilly regions of Zargham Ababd in south of Semirom under natural rangeland uses, was selected and then 125 soil samples (0-10 cm depth) were collected. Soil organic carbon was measured for the collected soil samples. Topographic attributes were calculated by a digital elevation model with 10 m spacing. Finally, multiple linear regression (MLR) analysis and ANN models were developed for soil organic carbon estimation in the study area and then the developed modeless were validated by additional samples (25 points). The results showed that the MLR and ANN models explained 60 and 89 % of the total variability of SOC, respectively, in the study area using terrain attributes. Sensitivity analysis based upon the ANN models, revealed that the profile curvature, stream power index, slope, sediment transport index, wetness index, plan curvature and aspect were identified as the important topographic attributes influencing the SOC distribution within the selected hillslope. The overall results indicated that topographic attributes and hydrological process control a significant variability of SOC. Prediction of the statistical studied models in the study area resulted in mean error and root mean square error values of 0.25, 0.3 in MLR equation and 0.006, 0.027 in ANN, respectively. Therefore, the ANN model could provide superior predictive performance when compared with developed MLR model.

Information about the spatial patterns of soil biodiversity is limited though required, e.g. for understanding effects of biodiversity on ecosystem processes. This study was conducted to determine whether soil macrofauna biodiversity parameters display spatial patterns in the riparian forest landscape of Karkhe. Soil macrofauna were sampled using 200 sampling point along parallel transects (perpendicular to the river). The sampling procedure was hierarchically, maximum distance between samples was 0.5 km, but the samples were taken at shorter distance at different location of sampling. Soil macrofauna were extracted from 50 cm×50 cm×25 cm soil monolith by hand-sorting procedure. Abundance (Number of animals), diversity (Shannon H’ index), richness (Menhinick index) and evenness (Sheldon index) were analyzed using geostatistics (variogram) in order to describe and quantify the spatial continuity. The variograms of indices were spherical and revealed the presence of spatial autocorrelation. The range of influence was 1724 m for abundance, 1326 m for diversity, 1825 m for richness and 1450 for evenness. The variograms featured high ratio of nugget variance to sill (abundance (52%), diversity (55%), richness (53%) and evenness (35%)). This showed that there was the small-scale variability and proportion of unexplained variance. The kriging maps showed that the soil macrofauna have spatial variability.

Soil microbiological criteria are a complex reflection of interactive metabolic processes that may not be evaluated only by measuring a single parameter but rather it requires the simultaneous determination of more parameters and combining them. The objective of this research was to study enzyme activities: microbial biomass carbon ratios in salinized and none-saline soils in the presence and absence of plant's rooting system. This ratio indicates the amount of enzyme activity per unit of microbial biomass. In this study, five levels of salinity using NaCl, CaCl2, MgCl2 and KCl; with 2:1:1:1 ratio and three soils (unplanted soil, soil planted with wheat and clover) replicated three times consisted our factorial experiment arranged in a completely randomized design. Results showed that salinity caused significant reduction in enzyme activities: microbial biomass ratio in all three soils. Furthermore, at all salinity levels, unplanted and planted treatments had a significant effect on urease activity: microbial biomass carbon ratio and arylsulphatase activity: microbial biomass carbon ratio. However, there were no significant differences in ß-glucosidase: microbial biomass carbon ratio and alkaline phosphatase: microbial biomass carbon ratio among the three soils at all salinity levels. In the other words, the presence of plant did not have any substantial effect in increasing or reducing microbial ability to produce and synthesize these enzymes. The effect of planted and un-planted treatments on the ratio of L-glutaminase, saccharase and acid phosphatase to microbial biomass carbon in different salinity treatments were variable. In summary, results showed that the presence of plants may support the synthesis of some enzymes by soil microorganisms. But the synthesis of some other enzymes is not affected by the presence and absence of plants living roots. In other words, the effect of roots and its exudates on moderating the effect of salinity on the amount of the enzymes synthesized by soil microbes depends on the salinity level, plant type and enzyme.

Reference evapotranspiration (ETo) is an essential parameter required for proper management of agricultural crop irrigation. ETo is influenced by many different hydrological variables and as a result is a very complex procces. ETo is usually estimated by empirical or process-orinented models (mathematical relationships) from historical weather data. The need for accurate estimates of ETo and the complexity of developing models to describe such complex process magnifies the need for developing new data mining methods. In this paper, the possibility of using a combined method of multiple linear regressions with principal componenets analysis (MLR-PCA) for estimating reference evapotranaspiration was investigated. In this analysis, measured daily meteorological data of Kerman synoptic weather station recorded from 1996 to 2005 were used. Three principal componenets that explained 80% of the total variance of the data were recognized as the principle componenets and others as disorder. Using the extracted principle componenets, a multiple linear regression model was developed to estimate ETo. The statistic index of t for assessing the results of a fixed constant and each componenets of PC1 and PC2 were determined. According to the results, all coefficients were significant at the level of 95% and PC1 had more importance than the other component namely PC2. This revealed that the variables of radiation intensity, relative humidity, sunshine hours, minimum temperature and maximum temperature had more importance in estimating reference evapotranspiration than other climatological parameters. Comparison of MLR-PCA model with Penman-Monteith results showed that about 82% of the total amount of the ETo variance is defined by the three aformenstioned principle componenets.

Assessing moisture in the soil under cultivation of crops to achieve high performance and reduced water are necessary. Knowledge of the moisture distribution in the root zone, time consuming and costly field tests that simulation models, a suitable alternative in answer to issues of movement and are water distribution. In this study assessment of soil moisture, to aid SWAP simulation model was and above model Empowerment compared with field results was assessed. SWAP model based on the information in a field irrigated onion, equipped with drip irrigation systems and soil hydraulic parameters obtained from model RETC, were performed. Moisture Information with harvest soil from emitter place and 10 cm of the layers 15-0, 30-15, 45-30 and 60-45 were obtained. Comparison of simulated moisture with observations moisture to a depth of 60 cm in the emitter place and 10 cm it, in the form of graphs and calculation criteria of Root Mean Squared Error (RMSE), Root Mean Squared error of normal (NRMSE) and mean absolute error (MAE) was performed. Values of RMS, RRMSE and MAE in the normal place dropper 0.001, 0.03 and 0.07 cm3cm-3 and in 10 cm were 0.08, 0.02 and 0.07 cm3cm-3, respectively. Low errors calculated from the model SWAP, shows good accuracy of the model simulated moisture distribution in the root zone. Operations irrigation through a drip irrigation system, with irrigation 48 hours was equivalent to performance kg/ha 14780 against 14134 kg/ha estimated by the model will follow. In total, the results indicate that the SWAP model is able to respond with a valid enough accuracy and precision in a relatively short time to provide. This model can be as effective and useful tool for evaluating and optimizing the distribution of moisture in the root-crop area, used.Keywords:

A greenhouse experiment was conducted to study the effects of soil copper (Cu) and salinity application on photosynthesis parameters, enzyme activity and anatomical structure of two pistachio cultivars. A factorial greenhouse experiment was carried out as completely randomized design with three replications. Treatments consisted of four Cu levels (0, 2.5, 5, and 7.5 mg Kg-1soil as CuSO4.2H2O), five salinity levels (0, 800, 1600, 2400, and 3200 mg NaCl Kg-1 soil) and two pistachio cultivars (Badami-e-Zarand and Ghazvini). Results showed that application of 3200 mg NaCl Kg-1 soil, decreased transpiration rate and stomatal conductance by 69 and 16% respectively, whereas had no significant effect on photosynthesis rate. Also application of 5 mg Cu Kg-1 soil, caused maximum photosynthesis rate. Transpiration rate and stomatal conductance of Badami-e-Zarand was significantly higher than Ghazvini, but reverse trend was seen for photosynthesis rate. The highest salinity level (3200 mg NaCl Kg-1 soil), significantly increased SOD activity. Furthermore, all Cu levels increased SOD activity. As salinity increased, thickness of parenchyma layer and phloem rings, and number of resin channels of stem and root decreased and increased pulp thickness. Application of Cu in saline conditions, decreased thickness of xylem vessels and increased that of phloem rings and number of resin channels in stem.

In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different times of agriculture year of 2007-2008 were measured. The measured and simulated data were analyzed. The statistical comparison which was done base on the root mean square error (0.49 ton/ha), correlation coefficient (0.85) and modeling efficiency (0.84), for estimating the total crop dry matter of wheat and fodder maize showed that the estimated crop yield by SWAP agree well with observed values. Suitable values of statistical indexes obtained for estimating soil moisture and soil salinity by SWAP, indicated that considering suitable bottom boundary condition in SWAP which has important role on water and solute balance in soil, has affected on estimation of soil moisture and salinity considerably.

In order to evaluate the effects of different depths of irrigation by sprinkler irrigation system on water use efficiency (WUE) of new early maize cultivar KSC302, an experiments was carried out in Karj during 2006 and 2007. Experimental design was split plot based on randomized complete blocks with three replications. Main plots were three irrigation levels: 75%, 100% and 125% ETc (estimating by Penman Monteith model) and sub plots were three plants densities: 80000, 90000 and 100000 plants per hectare. The results showed that increasing in the levels of irrigation from 75% ETc to 125% ETc, has a significant effect on yield. Yield increase in 125% ETc treatment indicated that water requirement has not fully supplied in 100% Etc treatment, and the effect of deficit irrigation was intensified in 75% ETc treatment. Maximum maize WUE was (1.159 and 1.044 kg m-3) for 100% ETc treatment in the first and second years, respectively. Maize WUE of 1.1 kg m-3 was recommended as optimum level to be considered in cropping system for Karaj. Applied irrigation depth for optimum level of maize WUE was 900 mm

The saturated hydraulic conductivity (Ks) is an important physical property of soil. The direct measurement of this property in soils is a difficult and time consuming process. Pedotransfer functions (PTFs) provide an alternative by estimating soil parameters from more readily available soil data. The objective of this study is to determine effective factors on soil hydraulic conductivity using multiple-linear regression methods and to determine direct and indirect effects of input soil properties of model using path analysis method. 70 soil samples with medium to heavy texture were randomly collected from paddy fields in Guilan province after harvest of rice crop. Range of pH indicated acidic to neutral condition of paddy soils. Results showed that regression equation using geometric mean and standard deviation of soil particles diameter (dg and g), bulk density (b) and soil moisture at field capacity (0.033) as input variables, can estimate hydraulic conductivity with a good accuracy (RMSE= 0.5 and R2adj=0.84). Although correlation between bulk density and saturated hydraulic conductivity was positive, but according to path analysis results, direct effect of bulk density on Ks is negative. Moreover the highest direct effect of soil properties on Ks in paddy soil was through soil water content at field capacity that indicates importance of this factor to predict saturated hydraulic conductivity.

Drought is one the most complicated and unknown natural disasters and rainfed agriculture is often the first sector to be affected by drought. In this research, we consider the drought monitoring from both meteorological and agricultural points of view. We have selected Standardized Precipitation Index (SPI) among the meteorological indices, with a one month time scale for the synoptic station of Bojnurd. Although there are few exceptions in during (1996-2005) in 1996, 1998, 1999, and 2000, in which the severely and extremely dry category have been matched to the growth season of the rainfed, the results of SPI index from precipitation data of this station and the trend of drought variations from 1996 to 2005 show that in Bojnord synoptic station, the meteorological drought has not happened in the growth season of the rainfed wheat (23 Oct. To 17 June) or at least it has been near normal category. The periods from June 1998 to May 1999 and from June 2004 to June 2005 have been the driest and wettest periods, respectively. The meteorological indices such as SPI, either are only the function of precipitation, or consider a long term time scale. In the first case they do not give a comprehensive analysis on the drought phenomena and cannot give be used for the monitoring of the crop moisture situation and in the later case, they are not applicable for short term time scales such as daily or weekly monitoring. Therefore, to monitor the agricultural drought and influence the other factors such as the temperature along with precipitation, the crop moisture index (CMI) has been introduced for weekly monitoring. To achieve this goal, we have used the climatic data of Bojnord synoptic station over ten years from 1996 to 2005. The results from CMI index show that in the last week of grain filling, around the last week of May, extremely drought (-2.7>CMI>-3) has happened. Also, during the crop maturity, a exceptional drought has been monitored with CMI

Precise knowledge of all components of water balance is essential to optimize water use in irrigated agriculture. However, water balance components are difficult to measure in required time intervals because their measuring is time consuming and costly. Unsaturated zone simulator models are useful tools for predicting the effects of agricultural management on crop water use and can be used to optimize agricultural practices such as agricultural water use. This research has been done on Wheat irrigated farms in Neyshabur plain, that is one of important plains in Khorasan Razavi province. SWAP Agro-hydrological model, was used for simulation of water balance components and crop growth in three wheat fields: Farob Roman, Hajiabad and Soleimani. Input data for model was a combination meteorological and field data. RETC software package was employed to evaluate and calibrate the soil hydraulic parameters, used. Simulation period was selected from October 2008 until early June 2009, in accordance with the wheat growing season. Sensitivity analysis to soil hydraulic parameters showed that the model is more sensitive to and coefficients. Also, acoording to presented statistical parameters, the results showed that SWAP is able to simulate water flow in soil, truly. Mean R2 coefficient value was 0.62, Mean Error was between -0.1 to -2.28 and Relative Error was fluctuated between -0.33 and -12.69. Therefore, calibrated SWAP model can be used as an instrumental tool for calculating all components of water balance in field scale, with time and cost saving.