فصلنامه حفاظت منابع آب و خاک
سال چهارم شماره 3 (پیاپی 15، بهار 1394)

Deficit irrigation and suitable usage of saline water resources is such as optimization ways in water consumption and increasing water productivity. This experiment was carried out in factorial method based on randomized complete design with three replications for investigation of deficit irrigation and water salinity effects on Barhee date palm juvenile plants vegetative growth. The treatments were three irrigation depths of 100%، 85% and 70% water requirement and three irrigation water salinities of 2. 3، 8 and 12 dS/m. The plant water requirement was determined based on soil moisture deficiency. Soil salinity was measured with sampling from soil different depths. The results showed soil salinity had a direct and significant connection with irrigation water salinity. The soil salinity in irrigation water salinity of 12 dS/m was 1. 73–1. 84 times greater than water salinity of 2. 3 dS/m. The soil salinity was reduced with increasing soil depth. The irrigation depth had significant effect on leaf number، leaf length and leaflet number، while irrigation water salinity had significant effect on leaf number، leaf length، leaf width، leaflet number and truck perimeter. Interaction of irrigation depth and irrigation water salinity had significantly effects on all vegetative characteristics except leaf chlorophyll and leaflet width. Increasing growth characteristics of I1S1 treatment were 1. 3-3. 6 times greater than I3S3 treatment. The highest Barhee date palm juvenile plants vegetative growth obtained from I1S1 treatment that was on significant with I2S1 treatment.

Growing population and increasing industrial and agricultural activities and successive droughts have caused more attention to soil and water conservation. To achieve this propose using wastewater for irrigating agricultural lands increased in recent decades. This study aimed investigating the effects of wastewater including municipal، industrial wastewater and river water on some soil physical characteristics. This research done in the area of agricultural lands located in the city Lenjan Zarrin Shahr. The lands area that have the same parent material and irrigated with municipal and industrial wastewaters (each for 8 years) and river water (20 years) where were selected for treatment. After detailed analysis for each of the treatments listed in 4 replications and tests were used to predict and physical properties include were measured. The result showed that irrigation with municipal and industrial wastewaters increased the bulk density 1. 3 g/cm3 (in river water treatment) to 1. 63 and 1. 76 g/cm3. Irrigation with this wastewaters caused increase in aggregate stability to 0. 67 and 0. 69 mm in municipal and industrial wastewaters compare to river water (0. 27 mm). Decreasing the saturation soil hydraulic conductivity and infiltration and bimodal retention curve were other soil physical properties reactions to using municipal and industrial wastewaters. The result showed that irrigation with wastewater had negative effect on physical properties and caused change in particle size distribution and recommended that monitored effect of long-term using of wastewater on physical properties.

Soil erosion is one of the basic issues at global، regional and local scales. Considering management plans in hindering its effects has therefore significant importance. Additionally، application of additive materials including polyacrylamide is one of new techniques in the field of soil erosion control. Despite of application of Polyacrylamide in runoff and soil erosion management، its contemporary effect in type and the amount of usage has been less considered. The present study was therefore carried out in order to determine the impressibility of soil loss in small plots from application of flour and soluble polyacrylamide in different levels of 0. 4، 2، and 6 g m-2 under the laboratory conditions. To this end، three plots with dimensions of 0. 5*0. 5m and 30% slope were used. In order to apply the current study، rainfall was simulated on study plots with intensity of 50 and 80 mm h-1 and respective duration of 17 and 8 min after 48 h from using polyacrylamide in flour and soluble types. The results obtained from statistical tests verified significant (P=0. 00) effect of polyacrylamide type and different rainfall intensities on the amount of soil loss in different levels of the polyacrylamide usage. In addition، the performance of powder application of polyacrylamide under study conditions was found better than that recorded for the solute application and therefore is recommended for the purpose of soil loss control.

Soil structure is an important indicator for optimal management of soil and water resources. Because it directly influencing several physical characteristics of soils such as soil water status، hydraulic conductivity، heat and air contents، soil porosity and bulk density. However، due to complexity of soil structure، its quantitative description is rather difficult. One of the relatively new methods proposed to explain soil structure in a quantitative manner is the so-called fractal geometry concept. In this concept، by determining the fractal dimension of bulk soil، the stability of aggregates can be quantitatively analyzed at different scales. The objective of this study was to quantify soil structure stability using some classic indicators and fractal approach in a large scale. Consequently، 41 intact soil samples were taken from an agricultural area and their particle size distribution، soil bulk density and aggregate bulk density، were measured. The weighted mean diameter and geometric mean diameter of both dry and wet aggregates were measured using dry and wet sieving method. The fractal dimensions of all dry and wet aggregates were obtained using fractal models of Mandelbrot، Tyler-Wheatcraft and Rieu-Sposito. The results indicated that fractal dimensions of the number-size model of Mandelbrot for dry sieve series and the number-size model of Rieu-Sposito in the wet sieve series perform quite well. These two models could also provide reasonable agreement with classical geometric mean and weighted mean diameters of aggregates.

Joint Deficit Index (JDI) is computed based on combination of the 12 modified Standardized Precipitation Index (SPImod) corresponding to the 12 time scales 1-12 month using the empirical and theoretical copula functions. Researchers suggest calculating the JDI as empirically due to difficulty and time-consuming in computing its theoretical form. The aim of this paper is to compare the empirical and theoretical copula-based joint deficit indices at 42 weather stations in Iran for the common period 1966-2010. For calculating the theoretical JDI (TJDI)، we chosen the best copula function from the four candidate functions including Student’s t، Clayton، Gumbel and Frank using two information criteria. In contrast، calculation of the empirical JDI (EJDI) not need fitting any copula function to data، and therefore it can be computed more simply than TJDI. Results showed that the Student’s t copula is the best function at all selected stations; therefore، the theoretical JDI was computed based on this copula function. Although both indices، i. e. EJDI and TJDI showed a similar behavior of drought severity، the EJDI faced two problems in all selected stations: 1) The lowest value in the EJDI time series is frequently repeated in different parts of its time series، 2) The EJDI was not able to identify the peak of drought severity during the critical drought periods. In contrast، the TJDI did not face the mentioned issues and therefore that is suggested for monitoring overall status of droughts in the study area.

Multivariate statistical techniques، i. e.، correlation coefficient analysis، principal components analysis (PCA)، and hierarchical cluster analysis (CA)، were applied to the total concentrations of hazardous metals in soils around the Sarcheshmeh mine، that it is one of the largest Oligo-Miocene porphyry copper deposits in the world. For the study، 100 surface soil samples were collected around the mining and processing complex. The total concentration of heavy metals was measured by using four acid digestion and inductively coupled plasma (ICP-OES). Various indices including geo-accumulation index (Igeo) and enrichment factor (CF) were used for determining the contamination level of soil in the study area. Based on geo-accumulation index (Igeo)، major and minor hazardous element in the region was Cd and Zn، respectively. Enrichment factor (CF) has revealed that the main soil pollutant was Cd element and the minimum soil pollutant in region was induced from Co. The results obtained from the application of multivariate techniques on the soil data set showed that there is positively correlation between the elements such as Pb، Zn، Cd، Cu، Co، Fe and Mn in the study area. Also، there was a strong relationship among these elements based on the PCA and CA classification.