Showing 6 results for Adab
A. Mohammadi Mohammadabadi, S.j. Hosseinifard, N. Sedaghati,
Volume 12, Issue 43 (spring 2008)
Abstract
Effect of change from the conventional (flooding) to subsurface irrigation system was studied on mature pistachio trees (Cultivar Ohadi) in Kerman pistachio research station for four years. This experiment was carried out in a randomized complete block design including 7 treatments and 3 replications. The experiment also used two irrigation intervals (7&14 days) and three water rates according to pan coefficient (20%, 40%& 60% evaporation from surface of class A pan) for subsurface irrigation system with 6 treatments the conventional (flooding) irrigation system was tested as control. The pipes of subsurface irrigation system were installed at 90cm distance from trees trunk at each side of trees, and 50cm from soil surface. Mean of pressure and discharge in the pipes was 0.8 to 1 atmosphere and 5.4 Lh-1m-1, respectively. Different factors of quantity and quality pistachio yield, current vegetative growth, water use efficiency and soil electrical conductivity were measured. The results showed that change of conventional (flooding) to subsurface irrigation system is possible and the best treatment can have water rate of 7174 m3ha-1y-1 with 14 days irrigation interval. In comparison with other treatments, this treatment has better quantity and quality pistachio yield. Water use efficiency (WUE) of this treatment was 164g dry yield per cubic meter. Nevertheless, application of water rate of 4783 m3ha-1y-1 can result in the deficiency of irrigation water. At this water rate, WUE was 177g dry yield per cubic meter. However, it was found that the application of lower water rate (<4783 m3ha-1y-1) produced severe effects on the treated pistachio trees, e.g. decreasing the growth rate, yield and increasing the early splitting in pistachio fruits. Finally, it is concluded that 14-day interval irrigation is the preferred treatment for pistachio trees. Also, soil salinity showed considerable change in subsurface irrigation treatments after irrigation system was changed, especially in the first year.
S.mj Nazemosadat, H Ghaed Amini Asadabadi,
Volume 12, Issue 46 (1-2009)
Abstract
The Madden–Julian Oscillation (MJO) known as the dominant mode of tropical and extratropical intraseasonal variability has an important role in the coupled ocean-atmosphere system. This study investigates the eastward propagation of the MJO and its impact on monthly (February-April) maximum and minimum precipitation in Fars Province. The positive and negative phases of MJO were categorized for the period 1979-2002. The maximum and minimum values of monthly precipitation was then determined for each phase as well as for the entire length of records. The given results have indicated that, in February, both maximum and minimum precipitation during negative phase were significantly greater than the corresponding values during the positive phase. This implies that the enhanced February precipitation and flood events are associated to the negative MJO phase. On the other hand, severe water shotage in February was linked with prevalence of the positive phase. The results for April were mostly found to be similar to February except that minimum precipitation was not significantly associated to the positive phase. In contrast to February, minimum monthly precipitation in March was found to coincide with the negative MJO phase. Maximum precipitation, however, could coincide with neither of extreme phases of MJO.
M. J. Nazemosadat, H. Ghaedamini Asadabadi,
Volume 15, Issue 55 (spring 2011)
Abstract
The Madden Julian oscillation (MJO) is known as the primary mode of large-scale inter-seasonal variability in tropical regions, affectimg equatorial and sub-tropical climates. This study investigated the effects of the MJO on the occurrence of wet and dry spells in Fars province, central southern part of Iran, during November-April. Monthly precipitation data of nine stations spread over various parts of the province was analyzed during 1979-2005. Using two well-known MJO indices: MK and WH, the positive and negative phases of the MJO phases (enhanced and suppressed convective activity over the equatorial Indonesian region, respectively) were identified for monthly and seasonal scales. Precipitation-MJO composites were then constructed for the opposite phases. It was shown that for all the considered stations, seasonal precipitation during negative MJO phase was significantly greater (from about 2.5 to 6.0 folds) than the corresponding values during the positive phase. Moreover, the applied statistical tests proved that the frequency of wet or dry events was related to the prevalence of negative or positive MJO phase, respectively. As the positive MJO phase was engulfed, the probability of dry events varied from 60% to 84%. On the other hand, the probability of wet events was found to vary from 60% to 76% during the MJO negative phase.
H. Adab,
Volume 21, Issue 2 (Summer 2017)
Abstract
A limited number of agricultural weather stations measure moisture in the soil surface. Furthermore, soil moisture information may be required in areas where there is no weather station. The aim of the present study was to use Landsat 8 satellite images to estimate soil surface moisture in an area without agricultural meteorological stations. Gravimetric soil moisture for a total of 14 samples was calculated in the cold season in depths of 0-10 cm when Landsat 8 satellite was overpassing poor rangeland of North of Sabzevar. Furthermore, the first four principal components were extracted from seven Landsat-derived vegetation indices and bio-physical factors affecting soil moisture. Afterwards, the first four components were used to estimate soil surface moisture at the moment of the satellite passing the region using a multivariate linear regression and neural networks. The obtained results of instantaneous soil surface moisture showed that the neural networks had mean absolute percentage error of while classical regression analysis had mean absolute percentage error of 40%. The results also showed the benefits of using both in-situ soil moisture data and Landsat 8 satellite images to model instantaneous soil surface moisture content for areas lacking meteorological networks.
M. Raeisi Asadabadi, M. R. Nour, R. Fattahi,
Volume 22, Issue 2 (Summer 2018)
Abstract
In order to optimize the irrigation system performance, it is essential to get information about water balance components in the farm. So, the objective of this study was evaluating the performance of the WFD device in determining water penetrated fate in the soil at each irrigation occurrence as one of the important components in evaluating the irrigation water efficiency. By having the water amount infiltrated in the root zone and the deep percolation amount collected and determined by WFD device, contribution of surface losses related to every irrigation occurrence can be determined by the employing water balance equation. This research was carried out in the form of completely randomized design blocks in three replications and under the treatments of 60, 80, 100 and 120% of the irrigation requirement supply of a potato plant in the research farm of Shahr-e Kord University in 2014. To gather the growing season data, before the planting operation, various WFD devices were installed at different depths and locations along furrow. In addition to WFD data, input discharge (using counter), output discharge (measured by flume type 1) and values of soil moisture (theta-probe device) were collected during the harvesting season. The results showed that the mean Nash–Satcliffe coefficient of comparison between the values of calculated and measured surface losses corresponding to it, and also comparison of the values of the calculated and measured residual moisture before each irrigation occurrence were obtained to be 0.87 and 0.98, respectively. Quantity of this indicator in the two conducted comparisons represented the correct and exact performance of the WFD device in the farm operation evaluation. During the farm evaluation process under the experimental furrow, distribution uniformity averages in the experimental treatments were acquired to be 75.56, 83.78, 88.06, and 90.34%, respectively. Likewise, water amount average percolation of root zone (depth losses) in experimental treatments at each irrigation occurrence was measured to be 0.02, 0.07, 0.27 and 0.47m3 for each furrow.
O. Asadi Asadabad, S. H. Matinkhah, Z. Jafari, H. Karim Mojeni,
Volume 25, Issue 1 (Spring 2021)
Abstract
In order to investigate the effect of the type drip of irrigation methods, subsurface irrigation and furrow irrigation on the domestication of Hedysarum criniferum Boiss., an experiment with a randomized complete block design with three replications was implemented at Isfahan University of Technology for two years (2016 to 2018) . For this purpose, clay pipes were made and the plant was cultivated on the sides of clay pipes and types. Also, furrow irrigation treatment was applied as the control. During the experiment, all treatments received the same water and finally, some growth parameters were measured. The results of the study showed improvement in height (0.43 and 0.34), canopy cover (0.66 and 0.52), stem number (0.44 and 0.85), chlorophyll index (0.45 and 0.45), seed emergence (0.75 and 0.30), plant survival (0.78 and 0.55), yield (0.23 and 0.35), and water use efficiency (0.25 and 0.25) under type drip irrigation treatment, as compared to subsurface and furrow irrigation, respectively (P<0.05). In general, the type drip treatment is recommended in the early years of planting; however, since the maximum production potential of this plant is in the third year onwards, it is necessary to examine the results in the following years to recommend the proper irrigation method, especially the use of subsurface irrigation.
