Alireza Abdollahpour; Mojtaba Baranimotlagh; Amir Bostani; Farshad Kiani; Farhad Khormali; REZA GHORBANINASRABADI
Abstract
Introduction Globally, deforestation is the dominant land use change process and has severe effects on soil biogeochemical properties. Large areas of the north facing slopes of the Alborz mountain range in northern Iran are covered by extensive loess deposits. Loess often contain little clay results ...
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Introduction Globally, deforestation is the dominant land use change process and has severe effects on soil biogeochemical properties. Large areas of the north facing slopes of the Alborz mountain range in northern Iran are covered by extensive loess deposits. Loess often contain little clay results in a loss of SOC under cultivation. Deforestation and cultivation on the loess hillslopes in northern Iran have resulted in a deterioration of soil quality, particularly significant reduction in SOC. Loess lands of Golestan province in northern Iran is densely being cultivated following deforestation. Labile fractions of soil organic matter (SOM), rather than total SOM, have been used as sensitive indicators of soils' quality and response to agricultural management changes. Several physical, chemical, and biological methods have been used to distinguish between labile (or biologically active) and recalcitrant pools of SOM. So, this research aims to investigate the effect of land use change from pristine and undisturbed forest as a reference to other land uses on soil organic carbon components and fractions as an important indicator in the sustainable soil management system and maintaining fertility and controlling soil erosion. Also, the effect of these land use changes on total carbon, soil organic carbon, and finally on the physical and chemical components of soil organic carbon.Materials and Methods The study area is the Toshan watershed, which is located in the northwest of the city of Gorgan (Golestan province) in the north of Iran. Four major and dominant types of land use were considered in the study area, including a) garden (olive), b) agricultural (cotton), c) virgin or untouched forest, d) abandoned (raspberry). Soil carbon fractionation was done by two physical methods (soil aggregate fractionation method) and chemical method (hydrolysis of organic matter with hot water). The selection of soils in different land uses was such that they have similar initial conditions and therefore the change in soil carbon in each use is related to the change in land use. The obtained data were analyzed based on the factorial design in the form of completely randomized design and using SAS software.Results and Discussion The results showed that the highest amount of total carbon and soil organic carbon was observed in the forest treatment and in the first depth (6.02% and 3.5%, respectively), which had a significant difference compared to other land use treatments studied. The results showed that despite the absence of a significant difference between the two depths, the amount of stable organic carbon increased with increasing soil depth in agricultural and abandoned uses. The forest land use had the highest amount of stable organic carbon at the depth of 0-10 cm at the rate of 2.51%, followed by garden treatment at the same depth. The lowest amount of stable organic carbon was recorded in the abandoned land use treatment. The highest amount of organic carbon dissolved in water at both investigated depths was obtained in the forest management treatments and then in the abandoned management. While no significant difference was observed between the two investigated depths in the abandoned land use. A significant decrease in organic carbon fractions that can be extracted with hot water was observed in abandoned and agricultural uses, as well as their increase in forest land uses. After the forest land use, the olive garden land use had the highest amount of total and organic carbon, however, there was no significant difference between the agricultural and abandoned treatments. In forest and garden treatments, the amount of stable carbon at a depth of 0-10 cm is significantly higher than the amount of stable organic carbon at a depth of 10-20 cm. In the garden use treatment, the amount of organic carbon in the soil at a depth of 10-20 cm showed a significant increase of 35% compared to the first depth.Conclusion A significant decrease in organic carbon fractions that can be extracted with hot water was observed in abandoned and agricultural uses, as well as their increase in forest uses. In total, the results showed that the carbon of labile fraction was more responsive to the type of land use than other fractions, and among the different methods of carbon fractionation, physical methods showed a clearer response to land use change.
Shohreh Moradpour; MOjgan Entezari; Shamsollah Ayoubi; Salman Naimi
Abstract
Impacts of land use and geomorphology on some heavy metal concentrations in a part of Zayandehroud dam watershed IntroductionWith the rapid development of industry and urbanization, soil pollution with heavy metals as a result ecosystem destruction has attracted global attention. Pollutants are considered ...
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Impacts of land use and geomorphology on some heavy metal concentrations in a part of Zayandehroud dam watershed IntroductionWith the rapid development of industry and urbanization, soil pollution with heavy metals as a result ecosystem destruction has attracted global attention. Pollutants are considered environmental threats and among pollutants, heavy metals are known for their non-degradability and physiological effects on living organisms even at low concentrations. The close correlation of magnetic properties and heavy metals shows that magnetic measurement is an efficient and cheap tool to detect heavy metal contamination in soils affected by heavy industries and traffic pollution. Magnetic minerals in soil may be inherited from parent rocks (lithogenic origin), pedogenesis (pedogenic origin), or may result from human activities (secondary ferromagnetic materials). The concentration of metals can be influenced by geomorphology and various soil properties such as organic carbon, electrical conductivity. Land use directly or indirectly affects the geochemical behaviors of heavy metals through regulating soil properties. The main objectives of this study were to investigate the effect of land use change on magnetic receptivity and the concentration of some heavy metals including zinc, copper, iron, nickel, chromium, cobalt and manganese in the 20 cm soil surface layers, and to explore spatial distribution of magnetic receptivity and heavy metals under different types of land use and geomorphological units in the studied area.Materials and MethodsThe present research was conducted in Isfahan province in the center of Iran with an area of 227 Km2. This area has an average temperature of 9.8 oC and an average annual rainfall of 324 mm and an altitude of 2380 meters a.s.l. Based on Kopen's classification, the climate was classified as semi-arid with cold winters. Geologically, it belongs to the Sanandaj-Sirjan zone, the dominant rocks of the area include limestone, shale limestone, slate and Quaternary sediments. The most important land uses in the region included pasture, rainfed and irrigated agriculture, and in terms of geomorphology, the region comprised river plains and pediments. Soil sampling was done by stratified random method. A total of 100 samples were collected from the surface layer (0-20 cm depth) in the summer of 2021. Magnetic susceptibility was measured at high and low frequencies using Bartington MS2 dual frequency sensor. The concentration of heavy metals including iron, zinc, manganese, nickel, copper, chromium and cobalt were measured by atomic absorption spectroscopy. pH, organic carbon, calcium carbonate, electrical conductivity were measured in all samples. Spearman's correlation coefficient was used to check the correlation between different parameters. Analysis of variance was applied to evaluate the effects of geomorphology and land use on heavy metals and magnetic susceptibility. Spatial analysis was performed for heavy metals and magnetic susceptibility, and the maps were prepared in ArcGIS v.10.7 software.Results and DiscussionThe results showed that there was a negative and significant correlation between calcium carbonate, heavy metals and geomorphology. There was no significant correlation between organic carbon and heavy metals in land uses. But there was a negative correlation in the river plains and alluvium. There is a significant negative correlation between electrical conductivity, copper, manganese, and nickel. In the use of agricultural lands and river plains, there is a positive correlation between low-frequency magnetic susceptibility and high-frequency magnetic receptivity with electrical conductivity. Also, pH showed a significant negative correlation with magnetic susceptibility in pasture land and had no relationship in other land uses. There is a positive correlation between calcium carbonate and frequency-dependent magnetic susceptibility in agricultural land use and river plains. There is a significant positive correlation between heavy metals and magnetic susceptibility in pediments and some land uses, especially in rainfed lands. The results of analysis of variance showed significant difference (p*<0.05) in land use regarding heavy metal concentrations. In this analysis, there was a significant difference between cobalt, nickel and manganese elements according to land use, and the magnetic susceptibility among the studied geomorphic surfaces. According to the results of the test, there was a significant difference for heavy metals in various geomorphic surfaces. The content of iron, chromium, cobalt, nickel and manganese in river plains and pediment had significant differences with hills.ConclusionThe present study was conducted with the aim of clarifying the effect of land use and geomorphology on magnetic susceptibility and concentration of heavy metals in a part of the Zayandeh River watershed in Isfahan province. The average of nickel and manganese in the soils of the study area is higher than the normal range, due to parent materials effects and agricultural activities (plowing and irrigation) accelerate the soil formation processes and increase the amount of these elements in the soil. The highest concentration of cobalt, iron, zinc, copper, nickel and chromium elements were observed in dryland farming. In addition, investigating the spatial distribution of magnetic receptivity values and heavy metals in different places are significantly different. Higher values of magnetic susceptibility were seen in the center of the studied area. Spatial distribution of heavy metals iron and chromium are concentrated in the center of the region and other metals are concentrated in the west and northwest. Probably, parent materials such as shale, dolomite, limestone and sandstone and weathering and release of elements in the soil increase the concentration of these elements in the region.Keywords: Geomorphology, land use, LSD test, kriging
Precision Agriculture
ُseyyed Mohammad Mousavai; Hojat Emami; Gholam Hosain Haghnia
Abstract
Extended abstract Introduction Knowledge about the soil quality in agriculatral lands and natural resources is essential for achievement the best management and maximum economic efficiency. The land use change is the important human activity in environmental ecosystems, which effect on some soil processes ...
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Extended abstract Introduction Knowledge about the soil quality in agriculatral lands and natural resources is essential for achievement the best management and maximum economic efficiency. The land use change is the important human activity in environmental ecosystems, which effect on some soil processes such as microbial activity, mineralization of carbon and nitrogen content. In addition, land use has an important role on temporal and spatial variation of soil properties and quality. Agricultural practices may affect positive or negative effect on soil quality. Intensive cultivation of plants decreases soil physical and quality, as a result of this yield of plants, production efficiency and environment quality decrease. In this research, the effect of three land uses on soil physical, fertility and quality properties were studied. Materials and methods The studied area (Hossein abad) is located 30 km far from the northern Nehbandan town (South Khorasan, Iran).To study the effect of land uses change on soil properties were selected three land uses including pomegranate (Punica granatum ), olive (Olea europaea) and wheat (Triticum aestivum ). The 45 soil samples (15 samples from each land use) were taken from surface soil (0-30 cm). Then some soil physical and fertility properties which affect the soil quality were measured and the effect of land use change from wheat cultivation to olive and pomegranate gardens during the recent 20 years were studied. In addition, soil quality in each land use was determined based on cornel university test. To compare soil properties and quality, the randomized complete block design was applied. Results and discussion The results showed that land use change had a significant effect on organic carbon, mean weight diameter of aggregates (MWD), water stable aggregates (WSA), macro nutrients (N, P, and K), and some micro nutrients (Fe and Mn) (P < 0.001). Comparison of means demonstrated that the difference between organic carbon content in olive and pomegranate land uses was not significant, and the content of OC in both land uses was significantly higher than wheat land use. Olive and pomegranate land uses cause to stability of soil structure increase, probably due to reduction the traffic of wheals and also somewhat increasing the organic carbon as a result of littering. Therefore, the MWD in olive land use was significantly higher than two land uses and the lowest value was obtained in what land use. Also, the value of WSA in three land uses was significantly different (P < 0.05) and their content in olive and wheat land uses were the maximum and minimum, respectively. The concentration of total nitrogen in pomegranate land use was more significant than two other land uses (P < 0.05). But the concentration of phosphorous (P), potassium (K), Fe and Mn in wheat land use was the highest content and significantly greater than other two land uses. Despite the concentrations of P, K, and Fe nutrients in pomegranate land use were the lowest value, but, there were no significant difference between the concentration of them in olive and pomegranate land uses. It seems that this variation especially P and Fe is probably due to pH and the Ca and Mg concentration and creation insoluble component of Fe, Mn and P in these land uses. According to the results of cornel university test, soil quality in garden land uses was decreased and the range of soil quality score was varied from 49.5 (olive) to 61.2 (wheat). Among the soil properties affecting the soil quality, fertility and chemical properties such as electrical conductivity (EC), absorption sodium ratio (SAR) and somewhat pH of soil saturated extract decreased the soil quality in olive land use. Also, OM, Fe, Zn, and Mn decreased the soil quality in 3 land uses, of course in olive and pomegranate land uses, micro nutrients (Fe and Mn) had the more effect on decreasing the soil quality compared to wheat land use. In addition, bulk density (Bd), mean weight diameter of aggregates (MWD), aeration porosity (AC), P, K, and Cu contents increased soil quality in all 3 land uses. Conclusion In general, when wheat land use change to olive and pomegranate land uses decreased some soil properties and quality in arid area of Nehbandan, probably due to low quality of irrigation water.
Soil Genesis and Classification
Maryam Mohammadzadeh Mohammadabad; F. Khormali; Farshad Kiani; mohammad ajami
Abstract
Introduction Soil degradation is a widespread environmental problem that occurs as a result of land use change and destruction of vegetation cover that may lead to changes in soil structure and porosity. Land use change and land management have significant effects on physical and chemical properties ...
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Introduction Soil degradation is a widespread environmental problem that occurs as a result of land use change and destruction of vegetation cover that may lead to changes in soil structure and porosity. Land use change and land management have significant effects on physical and chemical properties and biological capabilities of soil. The investigating of undisturbed and natural soil structure using microscopic and ultramicroscopic techniques provides invaluable information about the physicochemical, mineralogical, morphological properties and soil genesis and calcification. Image analysis is an advanced method for quantifying soil properties and increasing the precision of morphological and micromorphological studies. Materials and Methods In this study, in order to investigate the impact of different land uses on porous and microstructure of surface soil horizons, 9 profiles in different land uses, including natural forests, artificial forest, abandoned land, orchard and cropland were extracted and described. Then one sample was taken from each horizon for physical and chemical analysis as well as a few undisturbed samples for micromorphological studies. Physical and chemical parameters such as texture, bulk density (BD), calcium carbonate equivalent (CCE), organic carbon (OC) and mean weight diameter (MWD) were measured. After preparation of thin sections of soil, micromorphological studies were conducted by polarizing microscope. Then from each thin section, 20 photos were taken randomly in plane polarized light (PPL) and cross polarized light (XPL) and transferred to image tool software. The percentage of total porosity of soil, feret diameter and area pores parameters were studied quantitatively. Three classes of feret diameter in micrometer and five classes of area in square micrometers were considered for pores in the soil thin sections. After importing photos to the software and performing calibration, grayscale and subtracting two images, the range of pores was identified by the software. Then in the classification section of software, the highest level of classes in each part was determined and the percentage of pores in each class was calculated and data obtained were analyzed by SPSS 16.0 software. Results and Discussion Micromorphological observations showed that in natural and artificial forests, a significant amount of organic matter in the soil has resulted in the formation of granular and subangular blocky dominant microstructure. While in cropland land use the type of microstructure is mainly massive and angular blocky, due to deforestation and agricultural practices, which resulted in the degradation of soil microstructure. Appropriate environmental conditions and dense vegetation in natural and artificial forests land use lead to significant biological features in comparison to other land uses that were subjected to deforestation. In natural and artificial forests land uses, the percentage of channel and large vughs pores is more than other land uses mentioned above. Tillage results in degradation of soil structure in cropland land use, the majority of pores observed in thin section are vugh and plane. Also, the results of image analysis showed that in natural forests and orchard land uses, pores with diameters ranging from 2 to greater than 10 micrometer and areas ranging from 500 to greater than 1000 square micrometers had the highest frequency in terms of percentage of soil pores. Hence, these soils are considered as quite porous class, while in cropland land use, tillage results in the degradation of large pores showed that pores with diameters less than 2 to 10 micrometers and areas smaller than 5 to 50 square micrometers comprised and the highest percentage of soil pores. Conclusion Asignificant amount of organic matter and low bulk density, and the highest percentage of total porosity are found in natural forest and orchard land uses, while deforestation and cultivation in cropland land use has led to compression and destruction of soil structure. This fact reflects itself in the increased bulk density and decreased total porosity. Agricultural practice has a significant effect on destruction of surface soil structure. Microstructure and voids of cropland land use are mainly massive and angular blocky and plane and vughs, respectively. With changes of land use from forest to cropland, and consequently incorrect land management causes decrease in organic matter. Shortage of organic matter causes decreasing biological activity in surface soils. The best way to prevent degradation of the soil in this area is to preserve natural forests and change cropland land use to orchard and artificial forest land uses.
