Showing 3 results for Khayamim
A. Mousavi, F. Khayamim, H. Khademi, H. Shariatmadari,
Volume 18, Issue 67 (Spring 2014)
Abstract
In Iran, no research has yet been performed on potassium release from feldspar in comparison with that from muscovite. The objective of this research was to compare potassium release kinetics of these minerals as influenced by organic and inorganic extractants using successive extraction method. The experiment was carried out in a completely randomized design with a factorial combination. Treatments consisted of three kinds of K-bearing minerals (Muscovite, and Yazd and Ward feldspars), three extractants including CaCl2, oxalic and citric acids of 0.01 M concentration and 6 times of extraction (1, 2, 8, 24 and 48 hours). The results indicated that the potassium release from muscovite was 6-8 times higher than that from feldspars. The type of extractant significantly affected potassium release. Potassium release by organic extractants was 2.5-3 times higher than that by CaCl2 as an inorganic extractant. Different kinetic equations showed that power function, parabolic diffusion and first order equations adequately described K release whereas Elovich equation did not. Among the three equations, power function equation was selected as the best model describing K release from the minerals. Based on the selected kinetic equations, it seems that potassium release from K-bearing minerals is controlled by diffusion process.
F. Khayamim, H. Khademi, B. Stenberg, J. Wetterlind,
Volume 19, Issue 72 (summer 2015)
Abstract
Vis-NIR spectroscopy has been introduced as a non-destructive, fast, and cheap technique, with minimal sample preparation and no loss or damage to the environment. No investigation has yet been carried out to examine the ability of this method to estimate soil properties in Iran. The objective of this research was to investigate the capability of Vis-NIR spectroscopy to predict the amount of organic matter, carbonate and gypsum in surface soils of Isfahan province. A total of 248 surface soil samples were collected from the study area. Soil organic matter content, gypsum and carbonates percentages were measured by standard laboratory methods. Soil spectral analyses were performed by a field spectrometer using 350-2500 nm wavelength range. Different pre-processing methods were evaluated after recording the spectra. Partial least squares regression was used to predict soil parameters. R2 values for organic matter, carbonates and gypsum were 0.61, 0.45 and 0.8, respectively. Based on RPD (Ratio of Prediction to Deviation) values, the precision of prediction model for gypsum was quite good, and acceptable for organic matter, whereas the prediction of the model for soil carbonates was poor. Consequently, vis-NIR spectroscopy is capable of predicting some soil properties simultaneously and the model accuracy is acceptable.
F. Khayamim, H. Khademi, S. Ayoubi,
Volume 24, Issue 2 (Summer 2020)
Abstract
Understanding the abundance of clay minerals in soil and also, their spatial variability can provide more comprehensive information about soil properties, behavior and functions. The objectives of this research were: (i) to map the spatial distribution of the dominant clay minerals in the soils of Isfahan Province and its relationship with climate and parent materials, and (ii) to determine the quantity of the dominant clay minerals in different climatic classes of Isfahan Province. The amount of palygorskite, illite, expanded minerals and chlorite were semi-quantitatively determined for 100 soil samples collected from Isfahan Province. Maps of the dominant clay minerals were prepared by the Inverse Distance Weighting method. The results showed that palygorskite mostly occurred in the soils of dry areas with higher temperature throughout the province. This mineral was not present in the more humid areas of the province. Besides, palygoskite was found to be dominant in the soils derived from the Qom Formation, as well as Lower and Upper Red Formations belonging to Miocene and Pliocene. It seems, therefore, that the parent material plays a major role in entering palygoskite to the soil system, while the dry climate mostly guarantees the stability of this clay minerals and, to some extent, its limited neoformation in such soils. Both illite and chlorite occur in all soils throughout the province, regardless of their climate, following no particular trend. This may indicate that parent materials play a major role in the occurrence of these minerals. Both climate and parent material appear to have affected the distribution of expandable clays in the soils. In more humid areas of the province (west and southwest), climate plays a larger role in the distribution of this mineral. In other areas of the study region, especially in the eastern parts of the province with a much drier climate, the role of the parent material on the dominant soil clay minerals is more pronounced.
