Desert
Year:2007 | Volume:12 | Issue:1|Papers Count:12

An experiment was conducted to study wheat grain protein increasing through foliar application of Nitrogen after flowering. The RCBD design was analysed with three replications and four N-treatments as foliar application as (N0=0, N1=4kg.ha-1 Urea, N2=8kg.ha-1 Urea, N3=4kg.ha-1 Ammonium Sulfate). Results showed that seed protein content increased significantly by foliar application of Nitrogen. Data showed that there was significant difference among protein content of treatment. According to results, use of 8kg.ha-1 Urea was the best treatment for grain protein increase. In this treatment, seed protein content increased from 11.3 to 12.8 percent. Grain yield didn t affect by treatments.

Temperature is considered as the basic element of climate and also the environmental limiting factor in Lut Desert. In this research, in order to identify the temperature of Lut Desert located in east of central Iran, using remote sensing data, six series of MODIS sensor images related to June 24th & December 23rd 2002, and also January 22nd, March 22nd, June 22nd & September 24th 2003 were employed. The temperature rates have been stimated by using band numbers 31 and 32 with locative separation power of 1000 meters and considering the Sebal algorithm. According to the results of temperature evaluation, the mean for land surface temperature in Lut Desert within the mentioned images at 6 o’ clock Grinwich mean time have been, 49.6, 18.2, 22.0, 36.4, 55.7 and 54.2 C, respectively. Setting relation between calculated surface temperatures and recorded temperatures by meteorology stations indicated a meaningful correlation at 0.001 level. The rate of calculated determinant coefficients has been ranging from 0.91 to 0.72 per hour. Hence, the linier algorithms within surface soil temperatures of the six studied images and the recorded temperatures through meteorology stations were determined. According to these algorithms, the highest calculated air temperature in the area with respect to images was 49.7 C (at 12:00) in June 22nd 2003 and the lowest 11.5 C (at 03:00) Jan 22nd 2003. The results of this survey indicate that using MODIS sensor images seems to be suitable for estimating the Lut Desert temperature as well as temperature in other similar areas.

Physiological effect of five levels of water stress (0,-0.3,-6,-9 and -1.2MP) was studied on seed germination and tigella as well as radicule growth length in two different Artemisia species namely: Artemisia spicigera and Artemisia fragrans. Polyethylene glycol (PEG) was used to provide appropriate water potentials. A total of 50 seeds were sown from each Artemisia species. Experimental design was a factorial one of complete randomized design. Maximum germination rate was obtained at -0.3 MP. Germination rate, and tigella & radicule growth lengths declined with decreasing water potential level. Artemisia spicigera was more resistant to water stress in comparison with Artemisia fragrans.

Depth of frost penetration is one of the main indices in agriculture, civil and transportation engineering. Soil temperature is a function of several factors including: topography, solar radiation, air temperature, moisture content and other physical properties of soil such as thermal capacity, coefficient of heat conductivity, and specific heat. The main objective of the present paper is to determine the frost penetration depth in soils based on the air temperature. In this study the daily and hourly temperatures of air and soil at different depths of three climatology stations located at Shahr-e-Kord, Yazd and Urmia cities of Iran were collected and analyzed for a period of 11 years from 1992 to 2003. In the first stage, Air Freezing Indices (AFI) of the three named stations was calculated using three methods known as: American, Norwegian and Finn and then the results were compared with the observd values accordingly. Investigations showed that correlation between the results is significant at one percent level, but the three methods gave different figures. Based on other references, it has been shown that the American method is more suitable for regions located at the middle latitudes. Thus, the correlations between Frost Penetration Depth (FPD) and AFI based on the US method were calculated and found to be 0.88 and 0.82 for Shahr-e-Kord and Urmia stations respectively. However, the correlation for Yazd station was much lower (0.65), and significant (P<0.05). As a general, it was concluded that application of this method is more relevant to semi-arid rather than arid zones, but in the absence of a better method, the same index could be used for determination of FDP in arid zones as well.

Yield prediction before harvesting is one of the tools in order to planning food production supply in future. Yield prediction was carried out for Wheat (Triticum aestivum) using different meteorological variables with agrometeorological indices in Hamedan district during 2003-04 and 2004-05. According to correlation coefficients, standard error of estimate as well as relative deviation of predicted yield from actual yield using different statistical models, the best subset of agrometeorological indices were selected including daily minimum temperature (Tmin), accumulated difference of maximum & minimum temperatures (TD), growing degree days (GDD), accumulated water vapour pressure deficit (VPD), sunshine hours (SH) & potential evapotranspiration (PET). Yield prediction was done two months in advance before harvesting time which was coincide with commencement of reproductive stage of wheat (27th of May). It revealed that in the final statistical models, 83% of wheat yield variability was accounted for variation in above agrometeorological indices.

Soil salinity is one of the problems threatening agricultural lands. Parts of this phenomenon are related to geologic formations and saltpans, while some major factors are resulted from irrelevant agricultural activities, issue of irrigation, and improper cultivation systems which lead to increase in soil salinity. To avoid such consequences that would end up with ecosystem degradation, suitable management of these lands is indispensable. A research wasconducted in agricultural lands as well as in rangelands of Kermanshah province (in split plots with three replications) to analyze EC and SAR in the different layers of soil. The results indicated that there are significant differences among the treatments. Duncan analysis showed that the highest EC and SAR are related to deeper layers of soils in steep slope rainfed lands of Paveh, not suitably treated, while from more the top soils of gentle slope rainfed lands of Kermanshah benefit suitable treatment and management.

Prediction of annual average precipitation over a regin is one of important issues in watersherd management and natural resources planning. Geostatistics is one of the useful methods for precipitation prediction which varies based on type of the variable. This study was conducted in Karoon and Dez Basins located in southwertern of Iran. The data set including 20 years of annual precipitation of stations were used. At first normality and homogeneity of data are examined. Then variographic analysis using three techniques including kriging, co-krigining and Weighted Moving Average (WMA) were applied for predicting annual precipitation. Finally compaction of the results using statistical techniques showed that kinging method has the highest accuracy and provides more accentuate results.

This research was designed to evaluate and compare the applicability of two different types of irrigation including traditionally (surface irrigation) and simple sub-surface drip irrigation (using pricked-pipe covered with plastic cloth). Two plots containing 39 pistachio trees with 720 m2 area were selected in Rafsanjan, Iran. Both plots were irrigated using exactly the same quantity and quality of water for 2 years. At the end of the second year the yield was harvested separately and compared. The weight of fresh and dried crops in sub-surface irrigation plot to those of surface irrigation plot were 1.895 and 2 respectively. Annual shoot growth of tree was measured in two plats. The value of Plot Growth Index (PGI) in surface irrigation plot and sub-surface irrigation plot calculated 2237.5cm and 4580.5cm respectively. In addition, the dried weight of weeds in surface irrigation plot was 82kg while it was only 21 kg in subsurface irrigation plot. Results show the considerable difference in two irrigation systems efficiences and relatively higher preference of sub-surface system than traditionally surface method. Finally, due to sever shortage of agricultural water in the studied area, it has been advised to optimize traditionally used irrigation systems toward new methods with minimum water loss such as evaluated subsurface method.

Gully erosion is one of the most complicated and destructive forms of water erosion. In order to prevent this erosion, the important factors advancing gully head must be recognized. Nowadays, several models have been proposed in measuring gully head advancement and identifying the severity of erosion. These models must be calibrated for each country to see whether they are applicable or not. So it has been tried to study the necessities of the calibration in this research. This has been done in one of the sub-basins of Hableh Rood basin called Dehnamak in arid and semi-arid climate of Iran. Three aerial photos of 1956, 1967 and 2000 years have been used to measure the gully head advancement in different periods of time including 1956-1967, 1967-2000 and 2000-2005. Then in order to calibrate four models: 1- Thompson, 2- SCS (I), 3- SCS (II) and 4- FAO, all factors have been measured and studied. Statistics studies such as relative error percent, absolute error percent and change variable percent have been used. The results of the mathematical study show that SCS (II) and FAO model have a relative error percent and absolute error percent with amounts of 37.3 and 7.51 and, 40.06 and 18.21, respectively. Regarding to change variable percent, only 0.51% can be seen as a different between SCS (II) and FAO models, because of the usage of same factors and coefficients, each of two models are close to each other. Finally, the best models in the studied area are SCS (II), FAO and SCS (I) respectively, and Thompson model cannot be proposed.

Wind regime and sand grain size are two of the factors that determine the morphology and dynamics of sand dunes in desert areas. Regarding the importance of wind effects on sand dunes especially in Iran, in this study, Khartooran Erg was analyzed to determine wind direction and to detect sand source sites. Khartooran Erg is located on eastern north of Iran and lies in Khorasan Razavi and Semnan provinces. The area of Erg was determined based on geological and topographical maps and satellite images. Then, sand dunes of erg were classified, based on aerial photograph and satellite image interpretation. Sand dune forms in the Khartooran Erg are often barchans and combination of barchanic ridges, but there are also complex types of linear sand dunes. Based on field survey findings, the stabilized in the southern part of the Erg were separated, because of these sand dunes having been deformed. According to the presented models relationship between morphology and wind direction, the sand dunes were analyzed. The studies have shown that wind prevailing direction is eastern-north to western-south, the strong wind being in north-south direction. It can also be said that sand dunes which are located in the adjacent of Erg and are simple and separate can be used as the most suitable criteria to determine predominant wind. Also, regarding the Erg location with respect to upper plains and determined wind direction, it can be noted that sand sources mostly come from silt-clay flats of ending parts of Sabzevar Kal River rather than Jajarm Kal River.

To investigate pedological criterion on land degradation in Quaternary rock units, at first, a part of the shoor watershed area was selected. After distinguishing target area, slope classes, land use and geology maps were created, then map of units were founded by overlaying and crossing these maps. In this research three indices of erodibility, salinity and permeability of soils were considered that finally each of them was shown in the shape of classified map. Then by overlaying and crossing of these maps, a new map was created that is an expression of research area zonation from the viewpoint of indices that formerly, were explained. As determining and distinguishing of desertification intensity of potential of created units from crossing of indices was not possible with using of pure mathematical or statistical relations, so were exploited principles and concepts of fuzzy logic and statistics to achieve to main result. We used functions of fuzzy algebraic sum, fuzzy algebraic product and fuzzy gamma after determining weight or value of fuzzy gamma after determining weight or value of factors. Obtained results from a comparison of gained maps from different operators with an evidence map as control area including maximum of desertification intensity, were measured in research area, to prove fuzzy function usefulness for zoning of desertification intensity or potential in research area and similar area with function of 0.8 from fuzzy gamma model (gamma = 0.8 ). Finally by overlaying the desertification potential zonation map with geological map, kinds of soil zones were characterized on the base of their desertification effect. This research determined three classes of desertification qualitative potential (very high 23/08%, high 56/88% and moderate 20/04%).

Physical characteristics of different features in desert is a reflection of severe thermal and climatic conditions. In this paper, diurnal surface temperature patterns of important surface features in Lut Desert were studied and the relationship among different surfaces analyzed. Diurnal trend in surface temperature of surface types, marl, dark sand, light sand, salt-affected soil, soul at 10 cm depth, as well as dry and wet air temperature within 15 days were recorded in 2 hour intervals in the margin of Lut yardangs while correlations among these surface features and its significance level were investigated. The knowledge of diurnal temperature pattern and calculation of correlation among features can lead us to the understanding of the behavioral pattern and the trend of surfaces. The knowledge of behavioral pattern of correlation coefficients during different hours of the day provides the researchers the ability to produce optimal models of thermal characteristics and to predict them. Additionally, thermal data of different sensor systems along with their capability in the study of surface features in Lut Desert was evaluated. The results of thermal and inter-feature correlation analysis reveal a similar trend (at 8 AM and 4 PM) among various feature types. The orrelation coefficient of different surfaces shows the highest value at 6 AM and the lowest at 8 PM. The correlation efficient between sand and marl with grey sand and soil shows a non-linear trend at pre-noon hours while a linear and similar trend in the afternoon. Generally speaking, the correlation coefficient between surfaces at pre-noon hours as compared to afternoon hours is completely non-linear and does not reveal any specific pattern. It seems that TIR data acquired at 10 AM is the best choice in the study of Lut Desert and hence ETM+ and TM data can be used.