peyman afrasiab

Improvement of saline soils is very important from the point of view of soil and water resources conservation. Excess Solution salts in the root zone can reduce water uptake by the plant due to reduced soil osmotic potential. Necessary strategy in dealing with this issue is reducing the soil salinity to optimum level by capital leaching. The purpose of this study was to investigate the application of different amounts of leaching water in reducing salinity and evaluating experimental and theoretical models in predicting final salinity. This research was carried out in a part of Mohammadabad lands of Sistan plain as a randomized complete block. This experiment are carried out with five treatments and four iterations using test plots with one-to-one meter. Leaching was performed using 100 cm of water in four intervals of 25 cm. The required physical and chemical analyses before and after leaching and after the application of each irrigation cycle in treatments and at different depths up to 100 cm of soil were performed on the collected data. The results showed that the use of 100 cm of water for leaching could reduce the soil salinity class from S2A2 to S1A2. Experimental and theoretical models were evaluated and the results showed that theoretical models predicted the final salinity better than experimental models. Of all the experimental and theoretical models studied in this study, the theoretical model of a single reservoir with a correlation coefficient of 94% had the best results.

This study aimed to calibrate the HYDRUS-2D model for simulating soil moisture distribution under tape irrigation in transplanting sugar beet, with and without mulching. The research was carried out during the cropping seasons 2017-2018 in 14 plots (7 plots with mulch and 7 plots without mulch) with 2 rows of 40x50 tape. To monitor soil moisture distribution, soil samples were collected from 12 plots, and access tubes of the PR2 device were installed at depths of 10, 20, 30, 40, 60, and 100 cm in two plots. The PR2 device was calibrated for a 7- day irrigation frequency and 6 irrigations. The calibration results showed that the default parameters a0=1.6 and a1=8.4 proposed by the PR2 manufacturing company were not appropriate for the loam-textured soil of the study area. For this research, a0 and a1 were modified to 1.8 and 8.3 for soil water contents higher than the filed capacity and to 1.2 and 8.6 for soil water contents lower than the field capacity, respectively. The PR2 device was then used to measure soil moisture contents for five irrigations (6 hours each irrigation), during and after irrigation until the next irrigation. The results showed that the HYDRUS-2D model performs appropriately in simulating soil water content in five irrigation intervals with and without mulch application. The mean absolute value of error (MAE) was less than 0.035, root mean square error (RMSE) was less than 0.042; correlation coefficient (R) was above 70%, and the sum of squared error (SSQ) was less than 0.41 percent. If the hydraulic parameters of the soil were recalibrated for the use of mulch, the HYDRUS-2D model provided the same efficiency. Therefore, the HYDRUS-2D model is recommended for designing and managing tape irrigation due to its good simulation during and after irrigation.

This study aimed to estimate the spatial distribution of soil properties including field capacity (FC), permanent wilting point (PWP) and  total available water (TAW) using ordinary kriging (OK) and random forest (RF) in agricultural lands of the southern Sistan Plain, covering an area of approximtely 147000 hectars. FC, PWP, and TAW and soil texture components were measured for a total of 200 surface soil samples (0-30 cm). Performance evaluation of the two methods based on the percentage of normalized root mean square error (nRMSE) revealed that the conventional OK with 5% less error in estimating FC, 3% less error in estimating PWP, and 5% less error in estimating TAW performed slightly better than RF. Comparing Bias values showed that OK underestimates both FC and PWP and overestimates TAW, while RF overestimates all three parameters. Spatial distribution maps of FC, PWP, and TAW produced by OK model showed that the highest amount of FC (23%) and TAW (14.4%) were in the west and northeast of the region, which had heavier texture and lower altitude from the sea level. In the southern and southeastern regions, which have lighter soil texture, the amount of available water was less compared to the western and northeastern regions. In the RF model, the most important variable extracted from satellite images was Digital Elevation Model  (DEM), and all three features had higher values in areas where DEM was lower. It seems that the flatness of the study area and the inadequacy of auxiliary variables caused the lower accuracy of the RF method.

The FAO Penman-Monteith method as a standard method requires a lot of meteorological data. The accurate preparation of these data is not possible in all regions; as a result, alternative methods that require less data are investigated. Prestley-Taylor method require a few meteorological data and its application can be useful in areas where meteorological data is not available. The Sistan region in the southeast of Iran is one of the regions that is unique in Iran due to the 120-day winds and high day-night temperature changes. The purpose of this research is to evaluate Prestley-Taylor method compared to the PMF-56 method and to modify this equation according to the wind conditions for the region of Sistan. For this purpose, 30 years of meteorological data in Sistan region were used. The coefficient of Priestley-Taylor equation (α_PT) is one of the most important parameters which is used for evaluation of the equation. The results showed that the value of the evaporation coefficient in the main equation (1.26) for the Sistan region is too low and should be corrected. Its correction value varied between 1.02 and 6.11. The average value of α_PT was equal to 2.16, which is 71% different from the default value (1.26). Also, a regression relationship between wind speed and α_PT was presented. The results show that the amount of evapotranspiration obtained using the correction factor based on the wind speed (α_(PT-U2)) has the best results.

There are many methods for calculating evapotranspiration that require a lot of data, but a few require only air temperature. One of these methods is Trontwait. The Sistan region in the southeast of Iran is one of the regions that is unique in Iran due to the 120 days of winds. The purpose of this research is: 1) to evaluate 6 different Trontwait methods available in the sources compared to the Fau-Penman-Monteith method and 2) to modify the equation for the windy region of Sistan. The results showed that the original Trontwhite equation underestimates the amount of evaporation-transpiration. Among the existing methods, the use of coefficient k=0.72 had the best results. In order to recalibrate the Trunthwaite equation, the effective temperature coefficient of the equation (k) must be modified. The results showed that the optimal value of k varies between 0.755 and 1.04. The annual average value of the root mean square error (RMSE), according to the variable k values, was equal to 0.14 mm per day. Also, by minimizing the square of the error, we considered the k value to be 0.802 as a constant, and the RMSE value was equal to 1.19 mm per day. It can be concluded that after correcting the Trontwhite equation, it can be used in the Sistan region.

The proper combination of cutoff time and lengths of border are among the criteria for high efficiency in surface irrigation. The objective of this study was to determine cutoff time and the optimal distance and flowrate in closed-ended border systems. The basic assumption in this method is that the point along the field, where the lowest water depth permeates should receive water equal to the required depth. For this purpose, the data applied were consisted of 18 vegetated and non-vegetated borders, and bed slope of 0.001 to 0.005, Maning's roughness of 0.017-0.211, border length of 100 m and flow rate range from 0.08 to 0.16 m3/min.m. After determining the cut-off time, the application efficiency obtained using the method presented in this study was compared with zero inertia (WinSRFR 4.1) model. The highest similarity of results was observed in closed end border for R-6, R-13, R-14 and R-17 border with 0% difference and the highest difference was for R-1 border with 8.67% difference in efficiency. Maximum efficiency was obtained in some border with decreasing length and in some border with increasing length. Generally, it can be concluded that the application efficiency obtained from both methods was close to each other.

In order to determine the optimal performance of drip irrigation systems, their performance must be evaluated. In this study, five drip irrigation systems in Bushehr province were evaluated. A working manifold was selected from each system, and the evaluations were performed on four laterals from the beginning, one third, two thirds, and end of the lateral. At each selected manifold, eight pressures were obtained at the beginning and end of the lateral tube and 32 volumes of water at 16 trees. The average volumes of emitters and dispersion uniformity were calculated from the obtained volumes. The minimum input pressure of the experimental manifold and the operating manifolds were also measured to determine the Efficiency Reduction Factor (ERF) and the DCF. After collecting data from field measurements using scs and maryam and chlorine methods, evaluation factors such as water emission uniformity (EU), real low quadrant use efficiency (AELQ) and potential yield The lower quadrant (PELQ) was calculated. The results showed that water distribution uniformity varied from 77.98% in M5 to 92.12% in M3. Low quadrant potential (PELQ) efficiency with 82.91 and 70.18% and true low quadrant use efficiency (AELQ) with values of 92.12 and 77.98% were obtained in M3 and M5 systems, respectively. Indicates good to moderate status in these systems. In general, the main problem of the systems under study is the low level of wetting due to the make-up and the inappropriate number of drops, the lack of proper placement of loop rings, the lack of uniformity of pressure distribution in the system, and the lack of irrigation water, the distribution of air and the low knowledge and skill of the user.

Estimation of reference evapotranspiration (ET0) is essential to determine water requirements of crops. In other words, to regionalize ET0 to a large area, some interpolation methods should be used (Goovaerts, 1997). A key parameter which may influence the proper performance of interpolattion methods, is the sequence of ET0 estimation process (Mardikis et al., 2005; Vilanova et al., 2012). That is why using some auxillary variables cross correlated with the main variable, could significantly improve the accuracy of interpolation methods. Therefore, this study aims to analyze the estimation process sequences while investigating spatial variability of annual and monthly ET0 in Iran. A comprehensive comparison of spatial interpolators is performed. Elevation is also used as a secondary variable in multivariate methods.

Measuring the soil water retention curve in the laboratory is time consuming and costly. For this purpose, researchers have developed some methods to reduce measurements. One of these methods is scaling. The objective of this study is to scaling the soil moisture retention curve using Brooks-Corey model for all textural classes. This method requires a reference curve and the moisture content in a specified suction. In this method the scaling factor is the logarithm of water content in a specified suction (e.g.) in the reference soil to the logarithm of water content in the same suction of the proposed soil. The scaling factor obtained by the proposed method was evaluated with the scaling factor obtained by the statistical optimization method. In this study, 11 different soil texture classes data provided by Rawls et al. were used. The results showed that the scaling factor obtained based on the water content of ,  and  is close to the optimum scaling factor. The mean value of the sum of squares error for the proposed and optimization methods were 0.047 and 0.045, respectively. The mean value of the geometric mean error for the proposed and optimization methods were 1.024 and 1.047, respectively. The results showed that the reference curve is optional and each soil can be used as the reference curve. In the case of De-scaling, the soil water retention curve obtained by the proposed method was fitted very well to the one obtained from Brooks-Corey model.

Advance data and infiltration parameters are used to evaluate surface irrigation. Philip infiltration equation is one of the most widely used equations in surface irrigation. For the first time, Shepard et al. (1993) presented a one-point method to determine the parameters of the Philip infiltration equation in surface irrigation. In recent years, a new two-point method has been proposed to determine the parameters of Philip infiltration equation. In the new method, the volume balance equation is not presented. As a result, the Shepard et al. (1993) volume balance equation is used to determine the advance phase (Ebrahimian-Sheppard method). In this study, the volume balance equation for the new two-point method is presented. The volume balance equation presented in this study was evaluated with five independent furrow irrigation data sets and different input conditions. Results showed that mean value of root mean square error in Shepard et al. (1993), Ebrahimian-Shepard (2010) method and new two points were 40.5, 30.3 and 10.9, respectively. The absolute mean error of prediction had the lowest equilibrium of 9.6% in the new two-point method followed by the Ebrahimian-Sheppard (2010) and Sheppard et al. (1993) methods with 19.5 and 20.4%, respectively. The coefficient of determination for all three methods was more than 0.97. In general, it can be concluded that the method presented in this study predicts the advance curve with higher accuracy compared to the other two methods.

The economic value of water is one of the most important factors for allocating water among various consumptions and encouraging users to take necessary actions to increase investments related to improving water productivity. There are several methods for economic valuation of water. In this study, due to the key role of water in irrigation of agricultural products, residual valuation method was used for agricultural wells in Varamin County, with a wide range of water salinity. The average economic values of water for cucurbits, wheat, barley, and alfalfa were 2513.1, 5334.5, 1424.6 and 5647.6 Iranian Rials per cubic meters (IRR.m-3), respectively. The exchange price of water among the farmers in the study area was calculated as 5231.8 IRR.m-3, which was close to the calculated residual value for wheat and alfalfa crops. The coefficient of determination (R2) for the relationship of economic value and salinity of irrigation water for the above crops was 0.806, 0.878, 0.932, 0.911, and 0.702, respectively, which indicates that the main changes of economic value of water is related to salinity of water. According to the relationship between salinity and irrigation water value in the study area, the residual value of water was zero in the electrical conductivity of 3.61, 7.30, 5.20, and 8.24 dS.m-1 for cucurbits, wheat, barley, and alfalfa, respectively. As a result, the water pricing policy in the study area should be such that for water salinities higher than the mentioned values, the selling price of water is set lower than the current value, so that the farmers do not suffer losses. Another option is that choice of crop should be based on greater resistance to salinity and its economic value.

In traditional irrigation systems, inappropriate management of water allocation may lead to poor performance of the irrigation district, an increase in water losses, and a reduction in crop water productivity (CWP). Using optimization methods and nonlinear models along with the geographical information system (GIS) can improve the management of an irrigation district under uncertain condition. The objective of this study is to investigate the optimal water allocation and reasons for the CWP reduction in irrigation distribution district. To do so, in the first stage, those sites of water distribution district with the highest effects on CWP variability were identified. Then, the CWP was increased, later. For this purpose, fuzzy programming models and the possibility theory are used to prepare a water allocation plan for the irrigation system of Sistan Dam. The results show that the highest CWP of irrigation district for wheat fields is 0.45 kg/m3, which exist at the sites by the range of discharge losses in 360 to 400 L/m/hr. The analysis of these critical spots shows that the CWP values do not necessarily depend on crop productivity but they may depend on the management factors of irrigation district and the cultivated areas. Therefore, the spots with an optimized CWP could be considered as suitable patterns for increasing the management efficiency.

Freshwater crisis and soil salinity are the most important factors that limiting agriculture in arid areas. In these conditions, cultivation of medicinal plants with considering environmental aspects can be an intelligence strategy for these areas. For this purpose, a field experiment with four treatments and three replications was conducted in randomized complete blocks design in Zahak city during 2016-2017. The treatments were consisted of full irrigation with fresh water (F.FI), partial root zone drying with fresh water (F.PRD), partial root zone drying with saline water (S.PRD) and partial root zone drying with saline and fresh water (SF.PRD). The highest values of plant height (46.1 cm), number of umbel per plant (42), number of branches per plant (10), 1000-seed weight (0.86 gr) and seed yield (293 kg ha-1) were observed in F.FI. There were non-significant differences between F.PRD, FI and SF.PRD in most traits. Results illustrated that application of PRD with alternate fresh and saline water was the best option for decreasing fresh water usage in arid climate of Sistan region.

One of the methods for determination of infiltration equation parameters in border irrigation is the double rings. In this method, the parameters of the infiltration equations can be obtained by measuring the amount of infiltration at different times. Moreover, in recent years, the scale-up has been used to express the dynamics of water in the soil and reduce the required measurements. The objective of this study is to obtain the parameters of the Kostiakov-Luis infiltration equation using minimum field measurements. This research was performed using data from 15 double ring testing in different borders of the field in Zabol University. In this research to obtain the infiltration equation in each point, a reference infiltration equation with only one infiltration measuring time was used. In order to evaluate the accuracy of the method, the mean square error (RMSE) and coefficient of determination (R2) were used for estimating cumulative infiltration. The results showed that the reference curve choice was arbitrary and each of the 15 test points could be selected as the reference curve. The closeness of (R2) to one (0.99) and also low RMSE (0.001) indicate the high accuracy of the method presented in this study. Also, the scale factors obtained based on different infiltration times (0.5, 1, 2, 3 and 4 hours) are not very different. The advantage of the relationship presented in this study is requiring less input data and easier measurement as compared to other previous functions.

The relation between water table depth and evaporation rate from bare soil is of great importance in arid and semi-arid areas. In this region, due to over irrigation, the water table is very close to the ground surface which leads to salinization of the soil. Evaporation from soil columns in the presence of a water table is a important that has received great attention for many decades. The soil-drying process has been observed to occur in three recognizable stages. The first stage is evaporation with constant intensity. Secondly, evaporation is in descending order. The third stage is the residual evaporation of low intensity, which begins after excessive drying of the surface layer of the soil and its effect on reducing the hydraulic conductivity of the soil. Precise determination of evaporation from bare ground surface in semi-arid or arid regions then becomes critically important. The purpose of this study was to determine the effect of water table depth on the evaporation from soil surface, as well as the determination of different evaporation stages.

The soil used in this experiment was loam with a bulk density of 1.32 gr/cm3. The experiment was conducted in a greenhouse and the duration was 74 days. Soils Were sived through a 2-mm mesh and then packed into the soil columns using soil funnel. The soil columns were cylindrical PVC tubes of 200 mm inside diameter. Water table was stabilized at depths of 400, 600 and 800 mm from the soil surface, and the experiment was repeated twice. For stabilizing the water table in different depths, Each soil columns contained a pipe from the botton, to supply water from bottles that maintained the water table constant. The water losses from the soil profile was measured at different depths and times using Delta-T Device Moisture Meter.

The results showed that water content between 0 and 160 mm in the soil column were decrease during the experiment and close the water table depth remained saturated. In the steady-state, the rate of water loss from bottle next to the soil column is equal to the rate of evaporation from the soil surface. In a non steady-state, the rate of evaporation equals the sum of the rate of water loss from bottle and the water depleted from the soil profile. The maximum evaporation from the the water table was related to a depth of 400 mm and equal 384.6 mm and the highest water loss from the soil profile was related to a depth of 800 mm and equal 51.3 mm. By increasing the water table depth from 400 to 800 mm (increased 100%), the evaporation rate from the water table 24 percent and the total evaporation from the soil surface decreased by 16.5 percent. The length of the first stage of the evaporation for the water table depth 400 mm was 2 days and for 800 mm less than 1 day.

The results of this study gave us information on the flow of water above the shallow water table. Water content changes in the soil surface soil are higher than close watertable. Movement of water close water table is liquid and close the soil surface is vapor. The duration of the first stage of evaporation has decreased with increase water table depth. In general, it can be concluded that evaporation from the water table can provide a large portion of the water requirement by the plants.

One of the methods of indirectly measuring amount of soil moisture is using Theta prob device. Since it is based on the constant dielectric of soil, factors affecting the physical and chemical properties of soil have a great impact on the accuracy of the device measurement. The aim of this study is the effect of irrigation water turbidity on measurement accuracy of water content of the soil by Theta prob device. Because of this, three different soil texture (silty loam, sandy loam and loam) were on different levels of irrigation water turbidity. The levels of irrigation water turbidity include 10, 1000, 2000 and 3000 NUT. The result indicated that factors of soil texture and irrigation water turbidity in significant level (P

Subsurface drainage is constructed in the paddy fields with the purpose of drying of land at the time of rice harvest, mid-season drainage and lowering water level after the rice harvest. Most drainage equations have been developed for non-paddy land. However, given the unique special conditions of paddy fields in Guilan province (due to heavy textured soils with low permeability, heavy rain and shallow impermeable layer) compared to non-paddy lands, therefore introduced the equation that is most compatible with these conditions. So in this study, steady and unsteady equations were evaluated in estimating space of subsurface drainage for a second crop after rice harvest. Drainage treatments included: six conventional subsurface drainage systems including drainage system with drain depth of 0.8m and drain spacing of 7.5m (L7.5D0.8), drain depth of 0.8m and drain spacing of 10m (L10D0.8), and drain depth of 0.8m and drain spacing of 15m (L15D0.8), drain depth of 1m and drain spacing of 7.5m (L7.5D1), drain depth of 1m and drain spacing of 10m (L10D1), and drain depth of 1m and drain spacing of 15m (L15D1). From the rainfall occurred during the experiment, a three-day rainfall with a mean value of 23.9mm was selected for decision on the best equation. The equation that estimated the drainage space in the above rainfall with the least deviation from the best drainage treatment was chosen as the best drainage equation. The results showed that Ernst- Hooghoudt equation and Bouwer and Van Schilfgaarde equation combined with Hooghoudt equation estimated drainage space with the least deviations from the best drainage treatment (L10D0.8) and were selected as the best equations in the second cultivation season and the Delroix equation was introduced as the weakest equation in the design of subsurface drainage for paddy field in order to provide suitable conditions for the second cultivation.

In rice cultivation, mid-season and end-season drainage at harvest time are two important operations of water management which, respectively, increase yield and provide better conditions for harvesting rice. Due to the unique conditions of paddy fields of Guilan province, making decisions about the spacing and depth of drains and proper equation to determine the drainage spacing in paddy field requires research on the mid-season and end-season drainage. Therefore, in this research, the efficiency of drains spacing (L) and depth (D) of subsurface drainage in controlling water table and also accuracy of the steady and non-steady equations were evaluated at mid-season and end-season drainage stages in Guilan’s rice fields. Drainage treatments included six conventional subsurface drainage systems with rice husk envelope including drainage system with drain depth of 0.8 m and drain spacing of 7.5 m (L7.5 D0.8), (L10 D0.8), (L15 D0.8), (L7.5 D1), (L10 D1), and (L15 D1). All drain lines were 40 m long and made of PVC corrugated pipes with a diameter of 125 mm. Results showed that subsurface drainage with spacing of 15 m and depth of 80 cm (due to the proper water table depth and higher yield) and subsurface drainage with distance of 10 m and depth of 80 cm (due to the highest resistance to pentrometer penetration and the lowest soil moisture content) are recommended as the best drainage treatment for mid-season and end-season drainage, respectively. Dagan, Hooghoudt and Bouwer & Van Schilfgaarde equations combined with Hooghoudt equation were suitable equations for determining drainage spacing at mid-season drainage stage. Hooghoudt, Kirkham, Dagan, Bouwer & Van Schilfgaarde equations combined with Hooghoudt equation and Glover-Dumm equation were selected as suitable formulas for determining the spacing of subsurface drains for end-season drainage.

Soil moisture measurement is very important for better irrigation system management. One of the indirect methods for measuring the soil moisture content is to use Theta Probe device. Although the use of Theta Probe has many advantages over the other methods of measuring moisture content, but according to research conducted in most regions of the world, it has been shown that changes in the physical and chemical properties of the soil, and in general, all that affect the dielectric constant of the soil, cause an error in the accuracy of the measurement of moisture content with this device. Among the physical and chemical properties of the soil, the tissue type, the amount of clay contained in the soil, and electrical conductivity (EC) are the three main factors influencing the calibration of the Theta Probe system (Sarani and Afrasiab, 2012). The aim of this study was to investigate the effect of soil texture, irrigation water salinity (EC), and sodium absorption ratio (SAR) on the accuracy of Theta Probe device.

The Beerkan single ring infiltration experiment is a simple and inexpensive method for estimating soil hydraulic properties and is gaining scientist's attention in recent years. The purpose of present study was to compare the performance of modified forms of CL (cumulative linearization) and DL (derivative linearization) methods with the main Beerkan algorithm (i.e. BESTslope) in estimating saturated hydraulic conductivity (Ks) and the value of α (i.e. the ratio of gravity force to the capillary force) in the modified forms of CL and DL. For this purpose a number of 113 Beerkan infiltration experiments were carried out in Sistan Dam' research field. The negative values of Ks estimated by the BESTslope algorithm were eliminated and the 101 remaining experiments were selected for final analysis. According to the results, Ks values estimated by DL and CL were negative in most Beerkan experiments while the modified DL and CL methods resulted in positive values in all cases. The results were compared using a weighted coefficient of determination (ωr2). According to the results, the Ks values estimated by the modified DL were more similar to those obtained by BESTslope algorithm (ωr2 0.8135) when compared to those obtained by the CL method (ωr2=0.7506). Besides, the difference between Ks values estimated by BESTslope algorithm and the modified DL or CL methods decreased as the percentage of clay increased. The calculated value of α in modified DL (α =0.019) was more similar to that reported previous studies (in similar soil texture, i.e. loam and sandy loam) than that obtained in CL model (α =0.023).

In horticultural plants¡ determining of evapotranspiration because of The existing problems in the direct measurement such as installing large lysimeter or the exact equipment and length during tree growth¡ often estimated indirectly and on the basis of meteorological data. With regard to the spatial variability of meteorological parameters and sometimes inappropriate distribution of meteorological stations estimating evapotranspiration is not possible with sufficient accuracy. Therefore use of procedures such as the remote sensing methods that consider these changes is best. In this study¡ evapotranspiration of olive trees were measured and determined with direct and indirect methods in two growing seasons 1393 and 1394 in Tarom district of Zanjan at different development stages. The actual evapotranspiration were determined by direct method¡ By measuring the moisture balance components and in the indirect method with help from the satellite imagery of landsat 8. Then by determining of the reference crop evapotranspiration¡ olive crop coefficient were calculated and were compared and evaluated. The results showed that calculated evapotranspiration and plant coeffiecient of remote sensing mehod in various olive growth stages matched with moisture balance data. So that¡ evapotranspiration correlation coefficient was 0.73¡ 0.87 and 0.82 for first¡ second and cumultative year¡ respectively. Moreover¡ correlation coefficients of plant coefficient was 0.95¡ 0.62 and 0.86¡ respectively. It is concluded that remote sensing method can be useful to estimate evapotranspiration of olive tree.

present study was performed in order to determine effects of different amounts of irrigation water, plant density and planting pattern on yield, yield components and water use efficiency (WUE) of corn, variety single cross 700 (700KSC) using drip irrigation systems (tape) , in the research Station of Islamabadgharb in two consecutive years (2011-2012). The project was in the form of split block factorial experiment design That the vertical bar, was irrigation factor consists of four irrigation treatments of 50, 75, 100 and 125 percent evapotranspiration corn, And horizontal bars, were factor planting pattern include two planting pattern of one and two-row And plant density consists of three density of 65, 75 and 85 thousand plants per hectare and was implemented as factorial with three replications. The results showed that amount of irrigation and plant density at 1% level and their interactions at the level of 5%, created significant difference on water use efficiency. 50% treatment of the water requirement of corn with 0.8 kilograms per cubic meter and 100% treatment of the water requirement of corn with 1.25 kilograms per cubic meter, respectively, had the lowest and highest water use efficiency. Different amounts of irrigation water created difference at 1% level in yield So that 125% treatment of evapotranspiration of corn, with 11320 kg per hectare had highest yield and 50% treatment of evapotranspiration of corn, with 3442 kg per hectare, had the lowest yield also yield was influenced by the density and planting pattern and had significant Differences at 1% level. So that the density of 65 thousand plants and planting pattern one-row respectively with 6596 and 7894 kg per hectare had the lowest yield and density 75 thousand plants per hectare and planting pattern two-rows respectively with 8809 and 8195 kg per hectare had the highest yield

Due to limited resources, soil and fertile land, the need for maximum use of the potential of climate, Create favorable conditions for a variety of land use in the annual crop and most important of all completed equipping and modernization plans and land And scoring costs out, we can create a subsurface drainage, provides the possibility of planting crops other than rice in the wet season, in addition to creating more favorable conditions for planting and harvesting rice. In this research, the effect of depth and space subsurface drainage systems on drainage intensity was investigated in three stages (mid-season drainage, drainage in time rice harvest and drainage during second planting season).
Data needed for the study was obtained from paddy fields Rice Research Institute in the city of Rasht in an area of one hectare in crop year. Drainage treatments included: six conventional subsurface drainage systems with rice husk envelope including drainage system with drain depth of 0.8 m and drain spacing of 7.5 m (L7.5 D0.8), drain depth of 0.8 m and drain spacing of 10 m (L10 D0.8), and drain depth of 0.8 m and drain spacing of 15 m (L15 D0.8), drain depth of 1 m and drain spacing of 7.5 m (L7.5 D1), drain depth of 1 m and drain spacing of 10 m (L10 D1), and drain depth of 1 m and drain spacing of 15 m (L15 D1). All lines are 40 meters long and made of PVC corrugated pipes with a diameter of 125 mm. Rice husk was used as a covering around the pipe drain.
The difference between treatments L7.5D0.8 and L10D0.8 before tillage (there are more leaks and cracks) was not statistically significant, The difference between treatments was significant L7.5D0.8 and L15D0.8 at 5%. The difference between treatments L7.5D0.8 and L7.5D1 by 1% and the difference between treatments in the L10D0.8 and L15D0.8 by 1% level has been significant. In other words, the drain-distance 7.5 meters and a depth of 1 meter was increased discharge rate compared to 0.8 meters depth. The results showed that the difference between the treatment L7.5D0.8 with L15D0.8, L10D0.8 and L7.5D1 was significant 1% statistical level. Also in mid season drainage, spacing 7.5 m and a depth of 1 meter subsurface drainage almost 4 times the intensity of drainage compared to spacing 7.5 m and a depth of 0.8 m subsurface drainage. Most of the time difference between treatments in the drainage in order crop second in the state of cracks is in the peak of the hydrograph.
Cracks created at the time mid season and end season drainage at the time of rice cultivation a critical role has subsurface drainage and drainage parameters such as intensity during the second crop.

Conjunctional use of saline and non-saline water for reduce the negative effects of osmotic potential in the plant, has gained much attention. The aim of this study is to compare existing approaches and propose a new approach on how to conjunct saline and non-saline water. To do this, an experiment was performed as a randomized complete block design with six treatments and three replications for sorghum in experiment field of Zabol University within 2012-2013. Treatments include; control treatment (100 % freshwater), one-third of salty, the alternate time, the alternate place and the mixed. The investigated cropping indices were dry weight of stem, leaf and aerial organs of plant, plant height and leaf area index. The results indicated; both treatments the alternate place and one-third of salty, in all characteristics have been measured, after the control treatment had the highest yield, as the leaf dry weight, plant height and leaf area index did not show significant difference (p≤ 0.05) and in leaf dry weight and branch dry weight of the control treatment had the highest yield. These two treatments in salts adjusted at the end of the season left acceptable results. It seems local alternative and one-third of salty treatments with their own unique techniques in using saltwater reduce the negative effects of osmotic potential in the plant and compared to the older method (temporal alternative and), they have an advantage.

Crop residue management plays a significant role in sustainable crop production of agricultural ecosystems. The present study was performed to investigate the effect of crop residue burning on physical and chemical properties of different soils in Sistan plain. The experiment was carried out using a randomized complete block design with three replications. Soil texture was considered as the main factor at three levels (clay, silty loam and sandy loam) and burned and unburned crop residue treatments were considered as the secondary factor. Soil electrical conductivity, bulk density, pH, available P, K and Ca contents in burned plots were significantly increased compared with unburned plots and had no significant effects on soil organic carbon. There was a significant reduction in saturated hydraulic conductivity, soil water capacity and sorptivity factor in burned plots compared with unburned plots. The reduction was 28.1, 15.9 and 27.5 % for saturated hydraulic conductivity, 28.8, 27.0 and 53.7 % for water content and 41.7, 48.4 and 59.9 %for sorptivity factor in clay, silty loam and sandy loam texture, respectively. The soil water repellency was similar for both burned and unburned treatments and water drop penetration time was less than 5 seconds. In general, burning crop residues have detrimental effects on many physical and chemical characteristics of the soil. These effects were more obvious in light-textured soils. Thus, crop residue burning after plant harvesting is not recommended.