JWSS - Journal of Water and Soil Science

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The production and acreage of corn in Iran and in Fars Province, in particular, are expanding at an increasing rate. The impacts of this event was studied by a risk programming model (MOTAD). The results indicated that the optimal cropping patterns with corn had less variance than the optimal patterns without corn in all income levels. The results also showed that with the introduction of corn into cropping pattern, the use of land and water were increased, but the rate of increase in the use of land was more than the rate of increase in the use of water. By determining risk - aversion coefficient for the sample farmers, their sensitivity to corn price changes were studied. The results indicated that the relationship between corn and wheat is complementary but it is competing with barley, sugarbeet, cotton, cucurbits and legumes.

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Successful implementation of socio-economic projects depends on the degree of planners’ awareness of farmers’ risk coefficient. Because agriculture is a risky activity, knowledge about the farmers’ attitudes toward risk in each area is essential. This research investigated the farmers’ risk behavior in Homayjan district in Sepidan township. Cross-section and time series data were collected from a random sample of farmers and from Agricultural Department of Fars Province, respectively. In this study, the Safety First Rule (SFR), Generalized Stochastic Production Function (GSPF) and Target Motad models were used.

The results indicated that in this area, farmers are risk averse in crop production, but they have a low risk coefficient in the use of modern inputs. Signs of GSPF revealed that the use of modern resource input reduces risk. Target Motad risk programming model confirmed that farmers are risk averse because with increasing risk, crops like wheat that have relatively stable prices and yield enter the model, while crops like onion that have high instability in price and yield are omitted from the model.

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Marine products are currently important in Iran due to the following reasons: 1) aquatics are recognized as safe and healthy food by food scientists 2) because of low dependence of fishing technology on foreign resources, they are more reliable sources for protein and food security. Therefore, it is important to increase labor productivity using advanced fishing technology under a sustainable fishery management policy. In general, the prevailing methods of fishing in the southern coasts of Iran can be classified into three groups based on the level of technology and the length of journey made: traditional, semi-industrial, and industrial. In this study, labor productivity in the traditional and semi-industrial groups were compared using data obtained from a sample of 35 fishermen in Bushehr Province. To determine the marginal and average labor productivities, transcendental production functions were estimated for fish and shrimp, separately. The findings indicated that the marginal and average productivities of labor in semi-industrial fishing were significantly higher than in traditional fishing.

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Identification of easily measured physiological traits contributing to yield under specified environmental conditions would benefit genotypic selection for grain sorghum. A field experiment was conducted to determine broad-sense heritability and expected genetic advance, and to examine the relationships of grain yield with 11 physiological traits related to developmental periods, vegetative growth, growth rate, grain filling rate, and partitioning to the grain.

Sorghum genotypes exhibited significant differences for all traits, except for grain yield. Broad-sense heritability estimates ranged from a low of 49.6 (for grain filling rate per unit area) to a high of 99.4 (for days to maturity). Expected genetic advance ranged between 9.2% (for days to transition of vegetative to reproductive phase, days to maturity and number of leaves) and 39.8% (for grain filling rate per grain unit). Generally, grain yield gave a significant negative correlation with physiological traits related to development and vegetative growth. But, this correlation was positive and significant for growth rate, grain filling rate, and harvest index. Grain yield was low in its coefficient of genetic variation and expected genetic advance. It is, therefore, concluded that indirect selection for grain yield via growth rate, grain filling rate per unit area and harvest index is efficient. Results suggest that use of easily measured physiological traits in sorghum breeding is possible.

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In this study, the optimum irrigation depths for corn grain production under different conditions, i.e. maximum grain yield production and maximum benefit under limited land and water conditions, were determined under sprinkler irrigation in Bajgah (15 km. north of Shiraz).

 The results showed that, the optimum depth of irrigation for maximum grain yield production was 77.0 cm. Because of low price of irrigation water and sensitivity of corn crop to water deficit, the optimum depths of water were 76.8 and 73.4 cm under land and water limitations, respectively. Therefore, under limited water conditions, only 4.7 percent of the full irrigation water (maximum corn grain production) can be saved for maximum profits.

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In this paper, a simple farm management information system is introduced. This system was administered through cooperation between farmers and an information agency. The results showed that the farmers were willing enough to accept the system. Nevertheless, having an accounting system is the first step toward the establishment of an information system, which is used by only %42 of the sampled farmers. The main reason for this is the lack of knowledge about the benefits of such systems. In other words, if farmers were aware of the benefits of accounting systems, they would accept them easily. The results also showed that the farmers who use accounting systems are more successful in their production activities.

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Knowledge of forms of phosphorus (P) is important in the evaluation of soil P status and also in understanding soil genesis and fertility. Amounts and distribution of P in different organic and inorganic fractions were examined in 39 soil samples of Fars province. Soils were sequentially extracted to determine organic P and inorganic P fractions. Total P with an average of 597 mg/kg soil was lower in the light soils (482 mg/kg) as compared with the heavy soils (690 mg/kg). Organic P constituted considerable portions of TP (27%). Calcium phosphates with an average of 424 mg/kg soil and being comprised of 71% inorganic P was the dominant form of soil phosphorus. Simple regression analysis indicated that there were significant positive relationships between organic P, Ca phosphates and Al-Fe phosphate values with CEC and clay content. Stepwise multiple regression analysis showed that a combination of soil properties such as clay content and equivalent calcium carbonate (CCE) increased correlation coefficients (R). Alghough multiple regression model was significant (at P<0.05), the relative contribution of each soil property in Al-Fe-P fraction was not considerable.

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The objective of this study was to evaluate the strategies for groundwater resources management, including competition groundwater pumping, optimal control in groundwater pumping, groundwater use and tax policy, water users' participation in groundwater pumping control, and cooperation among government and water user associations in Narimany plain located in Khorasan Province. Irrigation water demand of sugar beet growers was estimated for empirical assessment of the strategies. The results indicated that among the strategies, groundwater use and tax policy may lead growers to sustainable use of groundwater resources. Furthermore, the results showed a desirable strategy is affected by cultural, social, and economic characteristics of growers and general prevalent conditions of society. Moreover, each strategy calls for its obligations, for instance, it is necessary to have an efficient taxation system for the proposed strategy. Hence, by internalizing the external cost of groundwater overdraft (that is taxing water users) government can force them to consider the adverse effects of their decisions on other producers.

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Tractive efficiency and fuel consumption of Massey Ferguson (MF399) and John Deere (JD 4230) tractors during plowing with moldboard plow were evaluated and compared. The tests were conducted at the Experimental Station, College of Agriculture, Shiraz University, in a field with sandy clay soil at average moisture content of 18% d. b. from zero to 30 cm depth. A randomized complete block design with a 4 3 factorial was used in three replications. The treatments consisted of two types of tractors, MF399 and JD 4230, each at two levels of axle load (standard and liquid ballasted) and three levels of plowing depth, shallow (15-20 cm), medium (20-25 cm) and deep (25-30 cm) using a semi-mounted 4-bottom moldboard plow. In all treatments, the tractor engine speed was set at rated rpm (2000 and 2200 for MF399 and JD 4230, respectively) and forward speed was kept constant at about 4.5±5 km/hr. The measured and calculated parameters included: drawbar pull, rolling resistance, wheel slip, tractive efficiency and fuel consumption. The results indicated that tractive efficiency of MF 399 in deep plowing increased from 36.5% to 53% with ballasting the drive wheels, even though the improved traction was not comparable to that of JD 4230 (64%) at the same plowing depth. However, at ballasted condition it is comparable to JD 4230 at shallow and medium depth plowing due to its lower fuel consumption. Using ballasted JD 4230 for shallow depth plowing is not economically justified due to the excessive fuel consumption and may cause soil compaction due to the lower than optimum wheel slippage. Generally, using MF399 is recommended for lower draft and JD 4230 for higher draft tillage operations. Otherwise, MF399 will encounter severe reduction in tractive efficiency and excessive increase in fuel consumption and JD 4230 will cause soil compaction.

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  Sugarcane is one of the most important sugar crops in the world. Because of semi-arid climate and salinity of its cultivation area in our country, increasing salt tolerance of sugarcane is signifying. To achieve this goal determining salt tolerant cultivars and understanding salinity mechanisms in sugarcane are very important. This study was conducted to evaluate 8 commercial and promising sugarcane cultivars at early stage of growth. A complete randomized design with three replicates and four salinity treatments (0, 0.25, 0.5, 0.75 % NaCl) was used in a hydroponics system. The effect of salinity on absorption, transport and accumulation of Na⁺, Cl^- , K⁺ and Ca²⁺ ions in shoot and root was determined. At high level salt concentration, Cl^- content in shoot and root increased. Result showed that sodium accumulation in sugarcane plants was more than potassium. By increasing salinity level, sodium uptake and its translocation to shoots increased reducing growth and dry matter yield of plants. With rising salt concentration from medium (0.5%) to high (0.75%), content of chloride in shoot and root of NCO-310 was constant showed that this cultivar had genetic ability to avoid Cl^- uptake. CP82-1592 with lowest ratio of shoot / root chloride had minimum transport of Cl^- to shoots. Also this cultivar had high content of Ca²⁺ in shoot and low Na⁺/Ca²⁺ ratio at all salinity levels. CP48-103 had low sodium in shoot and relatively low sodium in root. Thus it probably has genetic potential to avoid sodium uptake. At last, exclusion of Na⁺ and Cl^- to older leaves and tillers was seen in CP82-1592 and CP72-2086 cultivars. According to results, to avoid once of absorption and transport, and exclusion of harmful Na⁺ and Cl^- ions were mechanisms that could be used in salinity tolerance of sugarcane.

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The objective of this study is to introduce an approach for determination of comparative advantage of Basins in the production of crops, enhancing water use efficiency and directing cropping patterns to maximize net virtual water import. A model was constructed and applied assuming five different risks in available water and three levels of irrigation efficiencies (35, 45, and 65). The findings showed that, it is possible to direct optimal cropping pattern at basin level to maximize social profit, water use efficiency and net virtual water import simultaneously. However, in order to derive a definite conclusion, more data are needed about the quantity water embedded in each crop exported from and imported to each country. Moreover, it is necessary to design a suitable export-import plan to be used as a target for directing cropping patterns toward it. The approach used in this study can be viewed as a first step in this direction.

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‏Snow is a huge water resource in most parts of the world. Snow water equivalent supplies 1/3 of the water requirement for farming and irrigation throughout the world. Water content estimation of a snow-cover or estimation of snowmelt runoff is necessary for Hydrologists. Several snowmelt-forecasting models have been suggested, most of which require continuous monitoring of snow-cover. Today monitoring snow-cover patches is done through satellites imagery and remote sensing methods. MODIS have smaller Spatial Resolution and more bands in comparison with Meteorology Satellite like NOAA. Therefore, in this research we used MODIS data for creating snow cover imagery. Existence of cloud in the study area is a major problem for snow cover monitoring. Therefore, in this research snow cover area changes were estimated without MODIS data period, but with DEM imagery and regressions between temperature, height and aspect. For this purpose, on 10 Esfand when the image was suitable we estimated the snow cover area. In comparison with real image, precision of the method was confirmed.

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In order to determine the effect of climatic factors on distribution of Artemisia aucheri and Artemisia sieberi in Isfahan province, thirty nine most important climatic elements in ecological condition of these species were selected. Using a factor analysis method, the most important factors in distribution of these species were determined. These factors which cover 92.3% of the total variance of spatial variation of the species include rainfall, temperature and shining with 41.91, 40.18 and 10.23 percent, respectively. Four most important vegetative types of Artemisia aucheri and Artemisia sieberi in Isfahan province are as follows: 1-Artemisia aucheri and Astragalus,2- Artemisia sieberi,3-Artemisia sieberi as a dominant species, and 4-Artemisia sieberi as a subdominant species. Then the effects of climatic factors on distribution of these species and the average elevation of distribution of these species were determined. The effect of factor analysis on these types shows that rainfall and temperature are the most influential factors in spatial distribution of Artemisia aucheri and Artemisia sieberi in Isfahan province, respectively. In general, Artemisia sieberi has a higher extended tolerance range than Artemisia aucheri, and could be mentioned as a nearly universal species.

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Climate change has important effects on earth environment and human life. Therefor, investigation and study of climate change is very essential. This study investigated rainfall, temperature, relative humidity and wind variability by analyzing data for annual and monthly climatic factors collected at 13 synoptic stations (industrial cities of Iran) by using Mann-Kendall test. The results of monthly rainfall trends showed that most of synoptic stations have significant positive and negative trends in winter and spring months. About 23% and 1.7% of stations have significant negative and positive trends, respectively, in annual trend of this factor. The results of monthly number of rainy days showed the major number of significant trends occurs in spring. In autumn (September, October and November) like as summer most of the stations have no significant trends. Analyzing the annual number of rainy days trends also showed that 4 stations have significant positive trends and 2 stations negative trends. Trend of greatest daily precipitation is low throughout the year, so there is not any significant trend in winter. Annual investigations confirm the seasonal investigations. The major number of significant trends in monthly mean maximum temperature occurs in summer but there are not any significant trends in winter and March. The trend of mean minimum temperature is approximately high in all of the seasons and the major number of significant trends occurs in summer and autumn and then in spring and ultimately in winter. In annual investigation, most of the stations showed positive trends and only Oroomieh station has negative trends. Trend of mean temperature is high except for winter. Most of the stations showed positive trend, indicating increasing trends in this factor. Annual studies vertify the positive trends and about 63% of stations have significant positive trends.

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Low flow estimation and its characteristics play an important role in hydrologic studies. However, some low flow events are ignored compared with the lowest annual low flow that may have high risk. These events are taken into consideration by the use of partial duration or peak over threshold models. In this study, a 7-day low flow was applied for frequency distribution and threshold, and the lower events were considered as the number of low flow event ( ) to study seasonal variation of low flows together with two graphical methods. The results showed two major low flow seasons, and for other times of the year, the low flow events are negligible. At last, the region was divided into homogeneous groups based on seasonal variation of low flows.

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To investigate land use changes, Qale Shahrokh basin (15098.1 ha area) was selected. Satellite images of Landsat sensors (MSS, TM and ETM+) were used. After improvement and different enhancement analysis of images such as FCC, PCA, the study area was checked using GPS and topographic maps (1:50000) and other information. Land use units were determined using classified random sampling method. Maps accuracy was assessed after performing different classifications. Final land use maps of 1354, 1369, 1381 years were produced using a hybrid method with fine accuracy. Trend of land use changes was investigated during the study periods. Results showed that during the first period (1354), most area of land use was rangeland with sparse vegetation cover (%41.6) and least area was irrigated farming (1.5%). Also, during the second period (1354-1369) most area of land use was rangeland with sparse vegetation cover (%43.4) and least area was irrigated farming (4.1%). During the third period (1369-1381), the maximum area of land use was dry farming (%35.6) and minimum of area was irrigated farming (7%). Maximum land use change was related to rangeland with medium vegetation cover. They were changed into dry farming and rangeland with sparse vegetation cover during 1354 to 1369. During 1369 to 1381, maximum land use changes occurred on poor rangeland with sparse vegetation cover and rangeland with medium vegetation cover was changed into irrigated and dry farming.

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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.

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In this research, 5 percent of normal Precipitation Index (PNPI),Deciles of Precipitation(DPI),Rainfall Anomaly Index (RAI), Bahlme & Mooley Drought Index (BMDI) and standardized Precipitation Index (SPI) were used in order to investigate drought in Yazd synoptic station and 31 non synoptic stations all around this province. For this purpose, the present statistical errors were reconstructed via correlation between the stations, after raining data collection from the considered stations. Then, calculation of PNPI, DPI, RAI, BMDI and SPI indexes were calculated on monthly and annual scales. Situation of drought was determined based on the obtained values from calculation of each index according to tables related to the considered indexes in different classes of drought during the statistical period. Then indexes were compared to each other, considering drought given situation for each station. The difference and similarity of each index with other 4 indexes were calculated and investigated. Also after determination of drought situation in each station, given percentage of drought different situations via each Index was determined on annual scales, in 33 study stations. After passing the above mentioned stages, it was found that there was the highest percentage value of similarity between the two indexes RAI & DPI, as both indexes indicated similar situation of hard drought in the stations. These two indexes are considered most efficient to investigate aerology drought. But considering that static indexes are faced with problem on monthly scales and in stations located in drought regions, it is recommended to use‌ SPI & BMDI dynamic indexes whose similarity percentages are acceptable.

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This study performs trend analysis of hydroclimatic varibles and their possible effects on the water resources variability. Nonparametric Mann-Kendall and spearman tests were used to investigate trend analysis of mean annual and 24-hr maximum rainfall, flood and low flow parameters of 23 hydrometery and 18 synoptic stations in Sefid-Roud basin. The results showed that mean annual and 24-hr rainfall parameters are decreasing in few stations while most of stations representing negative trend for low flow and flood time series. Applying Sequential Mann-Kendall test revelad that this negative trend is started from 1965 to 1970 for rainfall parameters and from 1970 to1980 for flow (low flow and flood) parameters. Results show that climate change has probability affected variability of climatic variables, while changing of land use may have aslo affeteced extreme flow trends during recent decads. Therefor it can be noted that combination of climate chanege effects and human activities on water recources have affected the negative trend of hydroclimatics variables.

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In this study, in order to determe low flow conditions in Karkhe watershed, 5 indices of Q7,10, Q7,20, Q30,10, Q4,3 and Q95 were used for analyzing 12 hydrometric station data in the years of 1345-46 to 1380-81. Discharge data homogeneity was performed by Run Test. The Q95 index was determined by flow duration curve (FDC) and other indices were determined using 4, 7 and 30-day low flow frequency analysis. After calculating the indices, periods of low flows were determined. The indices were regionalized by Kriging method. The results showed that for the most stations, low stream flows happened in the years of 1345-46, 1377-78, 1378-79, 1379-80 and 1380-81 and the percentages of stations having low flows in these years were 68, 92, 84, 75 and 59, respectively. According to the regional maps of low flows in Karkhe watershed, maximum low flows are located in central and southern areas and all of the mentioned indices decrease from south to the north of this watershed.