Desert
Year:2001 | Volume:6 | Issue:1|Papers Count:10

One of the existing problems in studying natural resources is lack of standard and determined method so that, different methods for studies are applied with attention to existing conditions and skilled - men views. For example, watershed management, range management, and desertification have separate definitions which caused many problems in plans. In this research, two methods namely geomorphology and environmental were used for studying natural resources plans. In this study, Bidvaz watershed was chosen in Khorasan province in Esferayen city. Mentioned methods were compared in this cachments. 190 programming units were obtained (apart from units less than 25ha.) by environmental method. Since compiling 190 programming units in 50000 ha. Is too difficult, so this method can not be used in watershed, rangelands and desertification, but it can be used in, identification of environment units in vast area (for example a province). On the other hand, quantitative and qualitative erosion can not be estimated by environmental method. In mentioned catchment, 32 programming units were chosen according to geomorphology method. Thus, costs of studies in 32 units are less than 190 units. Finally programming units can be mixed with some common units then to reduce programming units more. By this method, soil erosion can be studied easily and with high percision from the viewpoint of quality and quantity and vegetation can be studied and planned in each programming unit according to other physical factors like water and soil.      

Water is the prime requirement for the existence of life. Due to the restricted resources of water in Iran, it is essential to save and economize in the use of water resources. It can be achieved by applying proper water management including: storage and maintaining soil water, improving soil water permeability and increasing consumption water efficiency. In this research, the effects of a soil conditioner, in different components of Sunflower yield soil water availability and amount of water consumption during the experiment have been studied. Sunflower was planted in pots containing three soils, the different textures and four levels of soil conditioner including 0.05, 0.01, 0.02, 0.03 weighted percentage. The results indicate that adding 0.05, 0.10, and, 0.03 weighted percentage of soil conditioner caused increasing of dry matter, 45.2,68.5 and 247 percent compared to control, in soils with fine, medium, and coarse texture, respectively. Leaf area was also increased in magnitude of 49. 2%, 33% and 219%, in fine, medium and coarse texture soil respectively. Application of 0.05, 0.1 and 0.3 weighted percentage- of soil conditioner results the increasing of plant height 21.7%, 9.8% and 91% in soils with fine, medium and coarse texture, respectively. Application of soil conditioner economizes water consumption on the basis of dry matter production. Using 0.05, 0.1 and 0.3 weighted percentage of soil conditioner causes in saving of water, 30%, 43.2% and 67.4% compared to control, in soils with fine, medium and coarse texture, respectively. Water holding capability in coarse - texture soil increased more than other soils. It causes in survive of plant during longer period after irrigation. Moreover, application of soil conditioner results in increasing irrigation intervals, in the fine soil, irrigation interval increases 29.5%, 50%, 81.8% and 127.3% by using 0.05, 0.10.2 and 0.3 weighted percentage of soil conditioner, respectively. It increases 61.3%, 83.8%, 83.8% and  116% in medium -texture soil, and 150%, 185%.,.235%, and 300% in soil with coarse texture.      

The study was carried out in Mirmohammad Ahram located in Tangestan (Boushehr province), which is a typical region in coastal desertland. In this investigation, soil factors were measured in 0-30 cm, 30-60 cm and 60-90 cm layers in March (after rainfall) and August (the driest month of year). Measured factors were texture, electrical conductivity, acidity, gypsum, organic matter, soluble cations and soluble anions. The ground water table, water table analysis, roots system in dominant species and corresponding agents in vegetation were also studied. The total species as especies radiance (Sr) in each habitant was determined. Relationship between species radiance and salinity agents in August is Sr = 15.256 - 0.17Ec. R2 is 57% in mentioned formula. The weakest correlation was between acidity and species radiance. According to the results, the moisture was the most important factor in distribution of holophytes. Topography changes have an important role in species distribution too. Flooding durations were also important in determining plant communities. 0-30 cm depth had the most important effect on plants. In general, holophytes are suitable index for soil characteristics (for example salinity).      

Performance of studies in the North regions of Iran in order to get proper management, sustainable exploitation and land restoration is fully necessary. In this way, recognizing the plant species and their reaction to climatic, soil and living factors enjoying a special status. Among the great watershed areas, Haraz watershed has a specific ecosystem that resulted to a different picture of vegetation. In this research, considering the appearance reasons of these plants, that mainly are calciphile, gypsophile, saliniphile, was carried out by choosing one of the sub-catchments of the Haraz watershed named Razan watershed that holds the conditions. In this research, through the study of geology, petrology, geo-morphology, pedology, vegetation, topography and meteorology, it was tried to recognize this special ecosystem. The results of the study show that the major factor of these plants development at first was the general topography of the region, secondly the petrological specification of the area and finally the lack of rich and developed soil. About the topographical condition, it can be said that this factor acts as an obstacle against the humid and rainy aerial blocks, partly preventing the transition of these blocks or changing their routes. Little raining on the lowlands and alluvium terraces causes unleashing of salts created and at the most, causing the increasing concentration of salts and eroded minerals, which in addition to the above mentioned factors, resulting a special plant coverage in this region, and generally all these factors causing the creation of micro-climate, and particular ecosystems among the valleys of Haraz, Chaluse, Sefidrood, and some specific regions of the North parts of Iran. The studying area known as Razan basin is about 14000 ha and its geographical coordinates is 52°.8' to 52°.18' Eastern longitude and 36°.1' to 36°.15' norther latitude. The area is a part of south of Nour city in Mazandaran province from the viewpoint of state political-administrative division.      

More than 90% of Iran's need to vegetable oil is imported from other countries. However, Lorestan porvince is suitable for soybean culture. An experiment was conducted at Agricultural Research Center of Khorramabad in which four indeterminate cultivars of different maturity groups namely Hack (group II), Bonos and Williams (group III) and Clark (group IV) were compared in a randomized complete block design with four replications. Soybean planted at 1994 when some crop such as barley, bean and rape seed were harvested in the region. The results showed that, the plant height of Clark, Williams and Bonos were taller than Hack (p ≤5). As far as the protein percentage was concerned, cultivars of group III maturity were significantly more than group II and IV. It was observed that the number of pod per plant of Williams, Bonos and Hack cultivars were significantly more than Clark (p≤5). There was no significant difference in grain yield of different cultivars. It was concluded that as far as the climatic condition and mechanical harvesting is concerned the cultivars of group III maturity is more suitable as a double cropping in region.      

Soil degradation including soil salinity, erosion and waterlogging are among main factors of desertification. In this research, attempts are made to evaluate the efficiency of Landsat TM data dated 28 June 1987 and geographic information system for studying soil salinity and salt affected vegetation. The study area is a part of Qazvin plain, located in the Roudkhaneh Shour catchement. The optimum band combination was selected for image classification using optimum index factor, two dimensional feature space analysis and principal component analysis. The training classes were selected based on the type, density of vegetation and soil salinity classes. Then 18 spectral classes were classified by maximum likelihood method. These classes were regrouped into three information classes and salt affected vegetation map was obtained. In order to calculate the correlation coefficient between the maps, the spectral and field soil salinity maps were crossed. The soil salinity map of the study area was elaborated in 1984. In order to map soil salinity, the salinity level of the soil was first measured for each horizon. Then a salinity rating is given for the layers: 0 -50 cm, 50 - 100 cm, 100 - 150 cm, by averaging the ECe data of the horizons. The three soil salinity ratings of the horizons were then converted into one final rating for the profile. The results have shown that the accuracy of spectral map obtained from remotely sensed data is about 86.4%, but its correlation with field soil salinity map is about 60% that is relatively low. The reason may be attributed to different approaches of mapping soil salinity and effect of some other soil physico - chemical properties on the surface reflectance.      

Domal structures produced by intrusion of salt into rock strata, are one of the most important geomorphological unit of the earth surface in Iran. The main area of these landformes is folded and thrust zones of Zagros - Range and central - Iran. They are dated back from Precambrian to nebgene age. These salt plugs are a mixed up & complex assemblage of various magmatic, sedimentary & metamorphic rocks which have been cut, replaced, mixed, disordered along up lifting. The occurrence of these Diapirs is due to the main stress from tectonic activity and buyonancy effect of salt masses. There are exposed and hidden diapers in Iran and they have oval, circular, irregular dome, and etc. shapes. In salt domes, solution is a dominant process in landform development with resulting production of Karst Topography. In many salt domes, salt has moved downhill on the form of the salt flows or glaciers. Salt diapirs of Iran are a wonderfull landscape and they have economic significance.      

In this project water erosion characteristics on marl formation were studied from view points of  geomorphology, vegetation and climate factors. Geomorphological studies were based on 1:50000 topographic maps, 1:50000 airs photographs, 1: 100000 geological map, 1:50000 slope map and field studies. These studies showed that some kinds of water erosion from least (sheet erosion) to most (badland) ones are available in the region. Vegetation studies in this region showed low variety of plants and very low density, so that plants variety doesn't exceed more than 10 plants and their density is less than 5%. For climatical studies, available data of the region were analyzed and factors such as: rain, temperature and wind were studied. Results of geomorphological, Vegetation and climatical studies showed that all morphogeneses of marl regions, whether in past or in present time, are due to the effects of rain and surface flow actions and in studied region effects of rain is related to rainfalls intensity with 15 to 30 minute durations in all returned periods which produce maximum floods. The studies also showed that general morphogenes formation is related to past weter climatical condition, because 'the most probable 24hr rainfall in this region is equal 121.2 mm from another viewpoint, evolution of formations in present climatic condition serve very slow in dry deserts and climatic factors such as rainfall and surface flows just polishes the past shape of formations.      

An experiment was conducted to study the water requirement of two varieties of Sorghum i.e. Speedo feed and Nothro feed in split, split-plot design in Yazd-Ardakan area. In this research, evaporative pan indexes (EPI) factors (0.4 and 0.6) studied as main factor and irrigation intervals (II) (5, 9 days) and two varieties of Sorghum considered as subfactors. Water salinity in the area was 2358 micro mhos/cm and area was covered with saline soil and considered antisoil in soil classification. Water efficiency in the area was 40% and plant index for Sorghum was calculated 0.3-1.1. Water quantity controlled by Parshal Flume. Parameters like, flowering percentage, number of leaf and tillering, diameter of stem, leaf area and yield were recorded in two harvesting times. Results showed that EPI was not significantly effected the yield, while irrigation intervals at 9 days reduced the yiels significantly. Total yield was 19.2t/h and 14.5t/h and 5 and 9 days irrigation intervals, respectively. Nothro feed variety yields 18.98 t/h and Speedo feed 14.75t/h. While Northro feed variety showed the best result in 5 days irrigation intervals at both 0.4 and 0.6 evaporative pan indexes, Speedo feed variety showed at 5 days and at 0.6 EPI. Considering economical use of water in the area and total yield (t/h), 5 days irrigation intervals at 0.4 EPI found suitable for the area.