Irrigation
Seyed Hamidreza Sadeghi; Mohammad Tavoosi; Somayeh Zare; Vahid Beiranvandi; Hengameh Shekohideh; Fatemeh Akbari Emamzadeh; Marjan Bahlekeh; Faezeh Khorshid Sokhangoy; Reza Chamani
Abstract
IntroductionCurrently, many disasters threaten the health of ecosystems. The pressures caused by extensive human interventions and the unprincipled exploitation of natural resources have led to the degradation of natural resources and the structure and functioning of ecosystems. Hence, evaluating the ...
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IntroductionCurrently, many disasters threaten the health of ecosystems. The pressures caused by extensive human interventions and the unprincipled exploitation of natural resources have led to the degradation of natural resources and the structure and functioning of ecosystems. Hence, evaluating the consequences of human intervention in nature and meeting the growing need of humans to receive diverse services has made it necessary to evaluate the performance of watershed ecosystems in providing different services. Healthy watersheds play an important role in providing a wide variety of ecosystem services. Therefore, watershed health monitoring and evaluation is vital for the conservation of ecosystems and achieving the optimal level of services. In such a way a suitable collaborative and executive approach is established between research and watershed management. In this connection, watershed health analysis can provide valuable help in achieving the goals of integrated management of watersheds and, of course, the balance between the needs of human societies and ecosystems. However, the assessment of the health and sustainability of the watershed affected by human activities has not been sufficiently documented yet.Materials and MethodsThe current pilot research has evaluated the health of the Shiraz Darwazeh Quran Watershed in Fars Province, Iran, and the effect of existing watershed management structures in the region on the health of the watershed with a focus on floods. For this purpose, 36 key criteria from a set of climatic, anthropogenic, and hydrologic factors were identified based on the conditions of the region and the analysis of the flood occurrence process in the watershed. The selected criteria were then categorized into the three indices of pressure (P), state (S), and response (R). After screening the selected criteria in exploring the conceptual approach of pressure, state, and response (PSR), the health status was evaluated in two cases with and without watershed management structures.Results and DiscussionThe results showed that the health condition without considering the watershed management structures was at average conditions with health index of 0.55. In addition, the results of the watershed health assessment verified the non-significant effects of stone and mortar structures on improving watershed health. So that, the health conditions was remained at average status with health index of 0.53. Therefore, it can be acknowledged that the existing watershed management structures, due to the limited both number and spatial coverage, have not been able to noticeably affect the improvement of the general conditions of the watershed, despite the effect on the factors affecting the health of the sub-watersheds where the structures have been constructed. The spatial changes of the calculated variables showed that the abandoned lands, time of concentration, area under military activities, surface of sensitive formations to erosion, high density of the drainage network, density of the roads, areas of regions with high potential in producing runoff and sediment, and size of the residential areas were the most important factors affecting the health situation of the Darwazeh Quran Watershed.ConclusionAccording to the results of the analysis of the indicators and criteria considered in evaluation of the health of the Shiraz Darwazeh Quran Watershed based on the PSR approach, it was found that the watershed had an average health status. Therefore, it can be acknowledged that the existing watershed management structures have not been able to impose a noticeable effect on the prosperity and improvement of watershed health conditions. In general, it can be said that abandoned lands, short concentration time, military activities, the presence of formations sensitive to erosion, high density of drainage network and road, and the potential of high runoff and sediment production, and the size of residential areas are among the most important factors affecting the declining the health of Darwazeh Quran Watershed. Therefore, it is necessary to pay further attention to the aforesaid factors by conducting periodical monitoring with more comprehensive data, in time and also analyzing the trend of relative changes of the indicators in order to explain the adaptive and intelligent management of the watershed. The necessary measures should also be taken into account simultaneously. Therefore, it is suggested to turn the weak points of the region into strong points by applying bioengineering measures and use the opportunities in the region such as the potential of tourism and ecological features in order to improve the health status of the watershed.
H. Dialami; J. Givi
Abstract
Abstract Introduction: This research aimed to evaluate the qualitative land suitability for irrigated cultivation of Date Palm (Phoenix dactylifera L. cv Kabkab) using FAO (parametric -the second root formula) and Multi-criteria approaches. The FAO approach has been used by many scholars in different ...
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Abstract Introduction: This research aimed to evaluate the qualitative land suitability for irrigated cultivation of Date Palm (Phoenix dactylifera L. cv Kabkab) using FAO (parametric -the second root formula) and Multi-criteria approaches. The FAO approach has been used by many scholars in different parts of the world and Iran for land suitability assessment. In this approach, the most commonly used method is the parametric method. The FAO approach uses Boolean logic to assess land suitability. This logic has been criticized by a number of land evaluation researchers. Because it does not take into account the continuous nature of the soil variations along the earth's surface and the uncertainty in the measurements. To overcome these shortcomings, the fuzzy analytical hierarchy process (FAHP) was presented to determine the land suitability classes. Land suitability should be determined based on a fuzzy analytical hierarchy process, in which, unlike the Boolean logic, unequal importance of different land characteristics and continuity of soil variations are considered. Materials and Methods: The studied area is located in Kheshet and Komaroj plain, Kazerun County, Fars province, southwestern- Iran; between latitudes 29º 32΄ and 29º 36΄ N and longitudes 51º 20΄ and 51º 22΄ E. Its surface area is 5000 ha. The mean annual rainfall and temperature are 377mm and 23 °C, respectively. The soil temperature and moisture regimes are hyperthermic and xeric, respectively. The physiographic unit is river alluvial plain with a very gently sloping. The entire Kabkab date palm plantation of Fars Province is located in this plain. To fulfill the objectives 10 date palm groves, each with an area of at least 0.5 ha and palm date (Kabkab cultivar) cultivation, aged between 20 and 25 years, identical in soil management and vary soil characteristics were selected. A soil profile was dug randomly in each date palm grove, with dimensions of 1.5 (length), 1(width) and 1.5 (depth) meters and described, using soil profile description (Soil Survey Staff). Soil samples were collected from each horizon. After pre-treatments soil samples were analyzed and some physical and chemical characteristics were measured using standard laboratory methods. The profile site was chosen to have a date palm tree in each of the four corners of the profile. The yield of the four trees in four corners of each profile was measured and their average yield was considered as the yield of the corresponding profile. Meteorological data was collected for a period of 10 year from the nearest synoptic station (Kazerun). Land indices were calculated, using soil and climatic data and FAO (parametric-second root formula) and fuzzy AHP and AHP methods. Weighted average of the climatic and the soil data were used and a land index was calculated for each soil profile. In the fuzzy AHP and AHP methods, relative weight of each of the studied criteria was determined by analytical hierarchy analysis using a pair wise comparison matrix. In the fuzzy AHP method the membership degree for each soil and climatic criteria was determined through an appropriate membership function and finally, land suitability class for each soil profile was determined. Landscape characteristics such as slope, drainage and soil depth were not considered in the land evaluation, because these characteristics did not show any limitation for the date production in the studied area. Finally the accuracy of the methods was compared. Results and Discussion: The results of qualitative land suitability evaluation based on FAO (parametric-second root formula) method showed that about 10 and 90 percent of the studied area were classified as S2 and S3, respectively. Based upon fuzzy AHP method, 100 percent of the studied area was classified as S2 and according to AHP method about 90 and 10 percent of the studied area were in S1 and S2, respectively. According to the results, the suitability classes resulted from AHP method was higher than of the fuzzy AHP and FAO methods. Correlation coefficients between the measured yields and the calculated land indexes showed that the fuzzy AHP method results was more correlated to the measured yield than of the other two methods which indicated that the fuzzy AHP was the most appropriate method for land suitability assessment for Kabkab Date palm plantation compared to the FAO (parametric-second root formula) and AHP methods. Conclusion: According to the results of this research, the fuzzy AHP was the most appropriate method for qualitative land suitability evaluation for Kabkab Date in compared to the other two methods in Fars province, Iran.
Niloofar Sadri; Hamidreza Owliaie; Ebrahim Adhami; Mahdi Najafi
Abstract
Introduction: Potassium is an essential element for plant growth and exists as four forms in soils: soluble, exchangeable, non-exchangeable, and mineral. Soluble and exchangeable K are considered as readily available and non-exchangeable K as slowly available. Organic matters and acids play an important ...
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Introduction: Potassium is an essential element for plant growth and exists as four forms in soils: soluble, exchangeable, non-exchangeable, and mineral. Soluble and exchangeable K are considered as readily available and non-exchangeable K as slowly available. Organic matters and acids play an important role in increasing the bioavailability of nutrients especially potassium in the soils. Organic acids are low-molecular weight CHO containing compounds which are found in all organisms and which are characterized by the possession of one or more carboxyl groups. Depending on the dissociation properties and number of these carboxylic groups, organic acids can carry varying negative charge, thereby allowing the complexation of metal cations in solution and the displacement of anions from the soil matrix.The ability of an organic acid to release K from soils depends on some factors such as: diffusion rate of the organic acid in soil, the diffusion capability of organic acid-element complexes, the contact time of the organic acid on a mineral surface, the ionization of the organic acid, the functional group of the organic acid and its position, and the chemical affinity between the organic acid and the mineral elements. This study was conducted in order to evaluate the effect of organic acids and vermicompost on transformation of K in some selected soils of Fars Province, southern Iran.
Materials and Methods: In this study, nine soils with enough diversity were selected from different parts of Fars Province. The experiment was done as a completely randomized design with three replications, consisting of three incubation times (5, 15 and 60 days) and four organic compounds (including 2% vermicompost, three acids of citric, malic and oxalic acid eachat a concentration of 250 mmolkg-1and one control). The samples were incubated at 50% of saturation moisture at 22°C. Routine physicochemical analyses and clay mineralogy were performed on soil samples. Soil reaction, texture, electrical conductivity, calcium carbonate, and gypsum were identified. Soluble, exchangeable, non-exchangeable and mineral potassium were measured. The amounts of K forms in each sample were determined. Total K was determined following digestion of soil (110°C) with 48 % HF and 6 M HCl. Water soluble K was measured in the saturated extract. Exchangeable K was extracted with 20 ml 1.0 M NH4OAc (pH 7.0) for 5 min. Nitric acid-extractable K was measured by extraction of a soil sample with boiling 1.0 M HNO3 for 1 h. Potassium was measured on all filtrated extracts by flame photometer. The content of clay minerals was determined semi-quantitatively, using peak areas on the diffractograms of ethylene glycol solvated specimens. Statistical analysis was accomplished using the SPSS 16.0 software and the comparison of mean values was done using the Duncan test at the 5% level of significance.
Results and Discussion: The amount of different forms of K including water soluble, exchangeable, HNO3-extractable, and mineral K are relatively high in the studied soils. Mineralogical analysis indicated that smectite, illite, palygorskite and chlorite were the major minerals in the clay fractions. The results also showed that exchangeable, non-exchangeable and total potassium were in the range of 166 to 378, 282 to 1694, and 2312 to 8437 mg/kg-1, respectively.Organic acids and vermicompostwere led toa significant increase in soluble K at all times compared to control and vermicompost treatment exhibited greater effect. These treatments also significantly increased exchangeable potassium compared to control. Significant differences between exchangeable potassium of organic acids and vermicompost treatments were not observed at 5 and 15 days, but significant differences were observed between treatments of mallic and oxalic acids at 60 days. Compared to the control, the non exchancheable K showed significant increase in all three organic acid treatments and vermicompost at 15 and 60 days.
Conclusion: Based on the results, while exchangeable and non-exchangeable (NEK) potassium showed a clear trend in treatments, solution potassium was first increased and then showed a decreasing trend due to the rapid changes in liquid phase compared to the solid phase. All treatments significantly increased soluble potassium in each 3 times. The greatest potassium increase associated with vermicompost. In general, oxalic acid> malic acid>vermicompost> citric acid, were increased exchangeable potassium, while the trend for NEK was in the order of oxalic acid> malic acid> citric acid>vermicompost, respectively. All treatments at all times (except for treatment 5 days of NEK), showed a significant increase in the exchange and NEK potassium compared to the control. The results also reflect the effect of the dominant soil clay mineral on transformation of exchangeable and NEK, so that the highest and lowest rate of increase was related to the soils with dominant palygorskite and illite, respectively. In general, it seems that the use of organic acids and organic matter leads to a rapid increase of potassium, which must be properly managed in the soils with high leaching. Due to the complexity of soil environment in terms of soil physical, chemical and biological aspects and the role of these factors on potassium transformation, repeating of this experiment in other soils is recommended.
J. Rahimi; A. Khalili; J. Bazrafshan
Abstract
The estimation of effective rainfall is an important technique for exploiting the rainwater resource, planning for irrigation in irrigated agriculture, and determining changes in dryland wheat products for country's macroeconomic management. In this research, a two-layer soil-water balance model based ...
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The estimation of effective rainfall is an important technique for exploiting the rainwater resource, planning for irrigation in irrigated agriculture, and determining changes in dryland wheat products for country's macroeconomic management. In this research, a two-layer soil-water balance model based on a new approach has been formulated to estimate the effective rainfall in dryland wheat crop. In this model, it is assumed that, in addition to the soil moisture retained on root zone on before day, also that part of water saved between the previous and current root-zone development add to the effective rainfall at current day. Greater ability of current approach to determine changes in wheat yields, which can be justified by changes in effective rainfall, confirms superiority of the current approach. Besides that, In order to estimate the effective rainfall in dryland wheat crop by this approach, daily climatic records during statistical period (1999-2000 till 2008-2009) from 12 meteorological stations of Fars province were collected. Results indicated that among the studied stations the amount of mean annual effective rainfall in dryland wheat crop changes from 296.4 (mm) in Doroodzan dam station to 112.6 (mm) in Abadeh station. Also, it is assumed that production of dryland wheat crop at north and northwest of Fars province is more success than other parts, due to satisfactory supply of effective rainfall.
