Showing 8 results for Ion Pattern
A. A. Vali,
Volume 10, Issue 1 (4-2006)
Abstract
Saline soils and halophytic vegetations are common features and part of the habitat pattern in deserts and steppes. The saline area is developing in arid lands. Investigation effects of halophytes on soil characteristics and adaptive mechanisms of the various halophyte types is essential for controlling saline environments. Juncus gerardi is a perennial grass-like halophyte and Halocnemum strobilaceum is a succulent halophyte shrub. The distribution of these species is mound like in the field. The soil samples of the mounds for investigating the effect of these species on plant root environment were compared with near regions in Korsiah saline area in Darab. Also the consentration some ions of live and dead organs and tissues of these species were studied for recognition of their adapive types. The results show that Juncus gerardi decrease salinity in 0-30 cm of topsoil, therefore the Ec decreased 37%. But salinity increased significantly in 30-60 cm depth. The identification of ions in plant tissues showed that the concentration of ions is low in dry matter. This is 0.33% of dry matter for Sodium. This is a way to rescue from dry conditions by selective absorption of ions. The comparison of root environment of Halocnemum strobilaceum with near regions showed a significant decrease in salinity in 0-30 cm and 30-60 cm depth decreased 27% and 40% respectively. The identification of ions concentrations in plant tissues reflect the high amounts of ions, therefore the plant tissues composed of 8.18% of Sodium. The comparision of ion concentrations in different live and dead tissues of plants a Significant increase of the amounts of ion in the dead tissues in comparison with the live tissues. Therefore this species excrete much quality of salts in their dead tissues and organs and so combat this problem.
M. Mousaei Sanjerehei, M. Bassiri,
Volume 11, Issue 40 (7-2007)
Abstract
Selection of efficient indices is very important for detecting and measuring random, uniform and clumped distribution patterns of plants in different plant communities. To compare and evaluate indices of dispersion patterns of plants, three stands were selected in Nodushan, Yazd. A (50m*100m) area was selected within each stand for sampling. Sampling was randomly systematicly conducted. Measurements and counts were made at 50 points and (1 and 2m2) quadrats which were randomly selected along four 100m transects within each sampling area. Indices of dispersion using quadrate studied in this survey include: Standardized index of Morisita, Morisita's index, Green's index, Dispersion (variance/mean ratio) index , Lloyd's index of patchiness and distance indices of dispersion including Pielou, Hopkines, T square, Eberhardt , Hines, Johnson and Zimer and Holgate indices. Results showed that T square and Holgate indices were more powerful than the other indices for detecting intensity of small-scale and tightly clumped pattern of shrubs because the two indices could distinguish between single individuals and the individuals on the edges of dense and small clumps. Johnson and Zimer index and Standardized index of Morisita (in shrublands with plant cover greater than 5%) were more efficient than the other indices for determining spatial pattern of these small clumps and single individuals. Among studied indices of dispersion, Green's index had the highest precision and with the exception of this index, distance indices were more precise than the quadrate indices.
A. R. Alipour, S. H. Mosavi, A. Arjomandi,
Volume 23, Issue 2 (9-2019)
Abstract
Increasing the productivity and conservation of limited water resources in the agricultural sector, especially in the agricultural sub-sectors, is closely related to the revision of the traditional approaches of production system in the agricultural sector of developing countries. The aim of this study was to develop the optimal combination of crop production in Varamin Agricultural and Animal Husbandry Complex as one of the leading agricultural units in the agricultural sector of Varamin County with the emphasis on increasing water use efficiency. For this purpose, the statistical data and information of the 2015-2016 crop year of the complex were used in the framework of the multi-criteria decision making model. The results showed that in the optimum crop pattern in this unit, the priorities of maximizing net energy production and the annual profit as the economic goals would be significantly aggregated with the goal of increasing water use efficiency. Accordingly, in the optimum condition, net energy production was increased by 10%, gross profit was improved by 4%, and water use efficiency was promoted by 15%. Therefore, according to the results, it is suggested that, in order to achieve the economic aspirations and increase water use efficiency in Varamin Agricultural and Animal Husbandry Complex, wheat, alfalfa, silage and maize corn, based on the values calculated in this study, constitute the main combination of the crop production pattern.
N. Ganji Khorramdel, M. Abdoos, S. M. Hoseini Mooghaari,
Volume 23, Issue 3 (12-2019)
Abstract
Due to water use increasing, attention to optimal water resources allocation is needed. In recent decades, the use of intelligent evolutionary methods for optimization of water allocation was focused more by researchers. The aim of this study is to development on water resources planning model that determined the proper cultivation, optimal exploitation of groundwater and surface water resources although water allocation among crops is a way to minimize the adverse effects of dehydration and increase its revenue. In this study, for maximizing profits, estimating crop water requirements at different periods to optimize the management of cropping patterns and irrigation management in cultivation in Varamin irrigation network using a new evolutionary algorithm was called the water cycle. Then for validation of this method is that a new approach and ensure the integrity of its performance Its results are compared with a genetic algorithm model and linear programming as our base (R2=0.9963). The results showed that the area cropping pattern was not optimal and the area under cultivation of crops such as wheat, barley, tomatoes, Bamjan, melon, alfalfa reaches zero and the new paradigm of the largest area under cultivation to industrial goods and then was assigned cucumbers. While our revenues have increased about 11 percent. In addition to amount of water in different months remain in the network that can be used for many that such as injection into underground aquifers or other crops based on the amount of water available.
H. Sadoghi, T. Rajaee, N. Rouhani,
Volume 24, Issue 4 (2-2021)
Abstract
Identification and investigation of changes in the area under cultivation of various crops seem to be essential for the management supply of crop production. In this study, r to identify and investigate change of the area under cultivation in major crop Hoseynabade Mishmast region in Qom province, we used the time series images of OLI and ETM sensors of landsat 8 and 7satellites, according to the crop calendar of this region. By using the vegetation index (NDVI) in the decision tree algorithm, the thresholds of this index were adjusted according to the major crops of this region; then a map of the cultivation pattern of the crop of this region was prepared. In order to evaluate the results, the statistics of the provinces agricultural jihad were used during 2005, 2009, 2014 and 2019 crop years. The results showed that by using the threshold of NDVI index, crops in this region in 2005 included wheat and barley and alfalfa, and their areas had an error of 17/1 and 6/1 percent in comparison with the statistics of agricultural Jihad, respectively; in 2009, wheat and barley, alfalfa and corn had an error of 0/5, 9/6 and 0/1 percent. Also, in 2014, wheat and barley, alfalfa, corn and sophie crops had an error equal to 4/9, 0.4, 11/4 and 2/4 percent, and the same crops in 2019 had an error 0/04, 11/6, 1/4 and 17/5 percent; that error was not significant. According to the results, the appropriate efficiency NDVI index in estimating crop cultivation area was determined by their phenology. Also, in 2009 and 2014, corn and sophie crops were added to the regions crops, and the area under crops cultivation in 2019 was increased, as compared to 2014.
A.r. Tavakoli, H. Hokmabadi, A. Naderi Arefi, A. Hajji,
Volume 25, Issue 4 (3-2022)
Abstract
Due to limited access to water, it is necessary to determine the comparative advantage of crops and horticultural products in different parts of the province and identify products that lack the desired productivity. Then, find ways to improve water productivity or replace products with higher comparative advantage with low-yield products. Based on this, the crop and economic productivity index of the province's agricultural and horticultural products under surface irrigation systems was determined. Based on the results of gross economic productivity of horticultural products, pistachio with 48690 Rials per cubic meter had the highest economic productivity, and grapes with 30220 Rials per cubic meter (62% of pistachios) was in second place. In addition, water quality for pistachios can never be generalized for grapes and other crops, and this is a tremendous advantage for pistachios that low-quality water resources can also be used. The lowest gross economic productivity of water for barley, alfalfa, and wheat is equal to 3790, 3990, and 4570 Rials per cubic meter, respectively. The study of fodder corn shows that the net profit from the cultivation of this crop in the surface irrigation system is equal to 51.78 million Rials per hectare and its net profit in the strip drip irrigation system (tape) is equal to 110.87 million Rials, which it has a 2.14-fold increase compared to the conventional irrigation method. The comparative advantage of horticultural products was higher than that of crops, and the replacement and development of orchards instead of some crops is recommended as a solution. In addition, solutions that can be recommended to improve the productivity index include the use of a drip irrigation system (tape) for crops (fodder corn, tomatoes, summer crops, and potatoes) and the use of drip irrigation (normal, subsurface, and subsurface modified drip) for horticultural products. Examination of practical experiences of using tape irrigation system for wheat and barley showed that this method has not improved the agricultural and economic productivity index, which indicates the lack of comparative advantage of wheat and barley cultivation in Semnan Province even with tape irrigation system.
H. Siasar, A. Salari,
Volume 27, Issue 1 (5-2023)
Abstract
Access to large precipitation data with appropriate accuracy can play an effective role in irrigation planning and water resources management. Satellite images generate high, wide, cheap, and up-to-date data is a good way to estimate precipitation. In this research, the Google Earth engine system and precipitation products from satellite images of PERSIANN and CHIRPS models in daily, monthly, and annual time intervals were used to evaluate and validate the amount of precipitation in Bandar Abbas station during the statistical period of 1983-2020. The results showed that the precipitation estimation by PERSIANN and CHIRPS satellites on a monthly and annual scale is more accurate than the daily scale. The highest correlation coefficient and the least RMSE belonged to the PERSIANN algorithm on monthly and annual scales. The value of the correlation coefficient in the PERSIANN algorithm on daily, monthly, and annual scales is equal to 0.32, 0.83, and 0.94, respectively. The correlation coefficient in the CHIRPS algorithm in daily, monthly, and annual scales is equal to 0.24, 0.71, and 0.90, respectively. The coefficient of determination (R2) of PERSIANN and Chrips algorithms on a monthly scale were 0.89 and 0.70, respectively, and for an annual scale were 0.88 and 0.80, respectively. The general conclusion of this study indicated that the accuracy of the two algorithms in determining the spatial pattern of rainfall on a monthly and annual scale is appropriate, and the PERSIANN algorithm had a higher accuracy on a monthly time scale.
S. Aghaei, M. Gheysari, M. Shayannejad,
Volume 27, Issue 2 (9-2023)
Abstract
Due to water scarcity, it is impossible to utilize all irrigated cropland in arid and semi-arid areas. Therefore, dense cultivation with a drip irrigation system that delivers water directly to the plant's root zone is an appropriate choice to enhance water productivity. The objectives of the present study were to compare wheat yield and water productivity under two different water distribution patterns in the drip-tape irrigation system and surface irrigation in full irrigation and deficit irrigation levels. The experimental treatments consist of two irrigation systems (drip-tape (DT), and surface irrigation (SU)), and three different irrigation levels (a full irrigation level (W1), two deficit irrigation levels, the irrigation interval twice, and the same irrigation depth of W1 level (W2), applied half of the irrigation depth of W1 level at the same time (W3)). The SU was implemented in place with 100% efficiency to avoid runoff. The yield in full irrigation level in DT was 5338.4 kg/ha and in SU was 5772.8 kg/ha. Applying deficit irrigation in two irrigation systems has different effects due to various water distribution patterns. In the DT, the most yield reduction was in W2, and in SU was in W3. The highest water productivity in DT was observed in W3 with a 1.44 kg/m3 value. The highest water productivity in SU was observed in W2 with a 1.46 kg/m3 value. For each irrigation system, some type of deficit irrigation management is optimal.
