sirous shakeri

The different landscape positions, the type of parent material and its formation processes, and the soil type significantly impact the distribution, behavior, and mobility of micronutrients. To investigate the effects of landscape and soil types on the distribution and behavior of micronutrient elements of iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn), some genetic horizons samples were collected from sixteen representative pedons in the calcareous soils of southwestern Iran. Subsequently, the concentrations of extractable trace elements were assessed using diethylene triamine pentaacetic acid (DTPA) as well as in their total form through digestion in concentrated nitric acid. The results showed that the change range in the available form of studied micronutrients varied between 2.5 to 31.2, 0.3 to 3, 2.1 to 60.2, and 0 to 3.8 mg kg-1 for Fe, Cu, Mn, and Zn respectively. The examination of the chemical forms of micronutrients in both surface and subsurface samples unveiled that the majority of the investigated chemical forms exhibited higher quantitative levels in the surface samples compared to the subsurface samples. v(%CaCO3) of the soil increased when the soil moisture regime largely depends on the percentage of organic carbon (% OC) content, soil texture, and type and content of clay minerals. The highest amounts of available micronutrient elements were found in Mollisols and Alfisols soil orders. Additionally, the highest available form of Cu, Zn, and Fe were found in lowland soil units (LL), while Mn was detected in piedmont plains (PP) landform. Consequently, it can be inferred that the cycling of micronutrients is influenced by varying levels of soil development, which in turn impact the properties of the soil.

The purpose of this research was to study the morphological, physico-chemical and mineralogical properties in different physiographic units of rangeland soils of Parishan lake  area in Kazeroon, Fars province with soil temperature and moisture regimes of ustic and hyperthermic, respectively. To this end, four representative soil profiles were selected on plateaus, hills, piedmont plain and low land physiographic units. Laboratorial studies were carried out on each soil sample after being air- dried, compacted and sieved by a two-millimeter sieve. Based on the laboratorial data, the soils of the area were classified as Entisoils and Inceptisoils with ochric epipedon and calcic and gypsic subsurface horizons. The result showed that soil factors have not had a significant impact on soil evolution and development in the lands under study in Parishan lake, which are located in four physiographic units and under rangeland use due to the low rainfall and calcareous soils.  It seems that among the five soil forming factors, topography and time have played more prominent role. The XRD data for the less than 2 μm fractions of the studied soils indicated that the soils were similar in their clay mineralogy, mainly consisted of illite, smectite, chlorite and palygorskite but were different in content. Illite and chlorite were higher in plateau and higher content of smectite was observed in low land unit due to low drainage condition. The source of smectite mineral of the  area soils can be inheritance, neoformation and transformation. Chlorite, illite and quartz are inherited and the resource of palygorskite is mainly inheritance and neoformation in the presence of gypsum and calcit. Finally, most of the soil's chemical properties, including organic matter, EC and gypsum, have had an increasing trend from the plateau physiographic unit to the low land.

The increase in the performance of cultivated plants is under the influence of various features including the soil properties. The nutrient elements of the soil are among the important soil features. The soil fertility should be studied to determine the proper level of fertilizer application. The improper use of chemical fertilizers with no attention to soil fertility not only does not increase the quality and quantity of the products but also imposes extra costs while unbalancing the level of nutritional elements of the soil and causing environmental problems. In this regard, the determination of soil fertility and providing a soil fertility map sounds necessary. In this study, the soil fertility of Shadkam plain in Eghlid county of Fars province was determined to prepare the soil fertility map for the cultivation of bean. The soil fertility map was obtained by a fuzzy system using a hierarchical analysis in a GIS environment. To this end, soil sampling was conducted from 210 locations and the input data including organic matter, potassium, phosphorous, iron, manganese, zinc, and copper concentrations were measured.  The interpolation of each soil element was achieved by the inverse distance weight (IDW) model in the GIS environment. Then, a membership function was prepared for each factor to obtain the fuzzy map considering their corresponding critical values. Finally, each layer was allocated with weight using the analytic hierarchy process. Based on the relative weight of each criterion, the highest relative weight (0.354)  was obtained for organic carbon while iron showed the lowest (0.031)  relative weight. The results also indicated that 0.3, 80.3, and 19.4% of the studied region can be categorized as very poor, poor, and moderate groups in terms of fertility for bean cultivation, respectively.

Phosphorus (P) is a nutrient essential for plant, which its availability in soils changes with aging process, leaching, precipitation processes, and the landform change. There is limited information available on kinetics release of P in calcareous soils. Therefore, the purpose of this study was to investigate distribution of P and the effect of physicochemical properties and clay minerals on its release in some dominant orders of the calcareous soils in Kohgiluyeh-and-Boyer-Ahmad province, using the 0.01 M calcium chloride ( ) extractant. The results showed that the P released rapidly from the soil and continued slowly. After 72 h, the amount of P released in the studied soils ranged between 3.2 and 25.4 mg kg-1. Evaluation of the fitted different equations on P released in the studied soils revealed that the Simple Elovich and power function equations could well predict the P release process in the studied soils. The results of the correlation between soil properties and released P contents showed that P release coefficients (including the slope and intercept in the Simple Elovich equation) have a significant negative relationship with the amount of smectite and vermiculite minerals. Also, the release coefficient of the parabolic diffusion equation had a significant negative relationship with pH and the amount of illite and palygorskite minerals.

Waterlogging is an important factor, affecting soil properties. This research was conducted to evaluate the effect of waterlogging on secondary soil clay minerals, as well as manganese (Mn) of paddy soils with long-term rice cultivation in Fars province. In each region, two soil profiles in paddy and non-paddy fields were digged on calcareous parent materials and the same landform in a pairwise manner. Analysis of the clay mineralogy indicated that the long-term rice cultivation seems to have an influence on the quantity of clay minerals, as indicated by higher smectite in paddy soils. But, higher chlorite, illite and palygorskite was found in non-paddy soils. Clay minerals were probably affected more by parent materials and less by the aquatic condition. Chlorite and illite were observed in both paddy and non-paddy soils and increased with depth due to their presence in parent rocks. Transformation of illite to smectite in the A horizon increased relative abundance of smectite but it decreased with depth. The results showed that the paddy soils have more available Fe and Mn (extracted by DTPA), total Fe and Mn (extracted by HNO3), and poorly crystalline Fe and Mn oxides (extracted by Ammonium oxalate), compared to the non-paddy soils and the surface horizons of paddy soils showed the highest rates. Also, the long-term cultivation of rice decreased the content of pedogenic (extracted by Citrate-Bicarbonate-Dithionite) and crystalline Mn oxides.

The present study was performed to investigate and compare some physico- chemical properties, clay mineralogy and different forms of potassium (K) of paddy soils with non-paddy soils and to study the effect of waterlogging on soil pedogenesis in some important paddy areas in Fars province. For this investigation, a paddy and non-paddy soil pedons within each area with similar calcareous parent materials and landform were dug and some soil properties and different forms of K in surface and subsurface soils were determined. The results showed that the average contents of soluble, exchangeable, HNO3-extractable, structural and total K in the non-paddy soils were 3.5, 199, 864, 4635 and 5502 mg kg-1; and in the paddy soils were 2.5, 164, 742, 5346 and 6088 mg kg-1, respectively. Results also indicated that the paddy soils had lower contents of soluble, exchangeable and non-exchangeable K due to the K leaching by irrigation water and removal by plant uptake. Significant correlations were found between different forms of K and some soil properties like clay, CEC and OC. The results of clay mineralogy indicated similar minerals, including smectite, illite, chlorite, palygorskite, vermiculite and kaolinite but with different relative abundance. Long-term rice cultivation seems to affect only the amount of clay minerals and converts illite and palygorskite to smectite. Significantly possitive correlations were found between non-exchangeable, mineral and total K with illite content in the clay fraction.

The pasture and forest land use change to agricultural use can effect on many properties of the soil and its productivity. The present research aims to investigate various forms of K (soluble, exchangeable, non-exchangeable, and structural forms) and some soil properties in different land use of three areas including Choram, Kakan and Bahmaei in Kohgiluyeh and Buyer-Ahmad Province. Four profiles were excavated in different land use of each area (In total, 12). All profiles were described and classified based on the Keys to Soil Taxonomy. The results showed that there is not any significant positive correlation between the clay and silt contents in different land use, while the lowest content of clay was observed in agricultural land use. The percentage of organic carbon was in its highest level in pasture land use (1.01%), and in its lowest level in agricultural (0.7%) and (0.4%) wheat cultivation. The highest and lowest pH levels were obtained in paddy soil (8.11) and garden (6.8), respectively. The average level of soluble, exchangeable, non-exchangeable, structural and total forms of K in the studied area were 0.5- 6.1, 45-262, 86-366, 835-5197 and 967-5555 mg/kg of the soil, respectively. The studied soils of Kakan and Choram areas had the lowest and highest levels of non-exchangeable, structural, and total forms of K, respectively. In addition, the highest levels of soluble and exchangeable forms of K were observed in Bahmaei and Kakan areas, respectively. The soluble and exchangeable forms of K had significant changes in different land use,

Determination and recognition of relative distribution of chemical forms of each element and their relationship with physical, chemical and soil clay minerals can help researchers to manage soil fertility better. This research attempted to recognize chemical fractions of zinc (Zn) and copper (Cu) in some surface and subsurface soil samples of Kohgiluyeh and Boyer-Ahmad province and their relation with physico-chemical properties and clay minerals. In order to carry out this research, surface and subsurface soil samples were collected in different physiographic units of the province and chemical fractions of Zn and Cu were measured by sequential extraction method and ultimately their relationship with different soil characteristics was investigated. Results showed that exchangeable and sorbed chemical fractions of Cu and Zn in all soil samples were lower than the detection limit of atomic absorption spectroscopy. Distribution of chemical fractions of both Zn and Cu followed the order: residual> carbonate> organic fractions. The low and medium mobility factor of Zn and Cu, respectively, in the studied soils indicated the different behavior of these elements in calcareous soils. Among all soil physico-chemical characteristics, organic carbon showed more obvious effects on controlling the chemical fractions of Zn. On the other hand, chemical fractions of Cu showed significant correlations with clay and silt content, as well as cation exchange capacity. The correlation between the clay minerals content with chemical forms of these elements showed that the amount of different forms of Zn and Cu is directly related with 2:1 clay minerals (especially vermiculite).