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Showing 3 results for Fractal Dimension
Fractal Description of the Impact of Long-term Grazing Exclusion on Spatial Variability of Some Soil Chemical Properties
J. Mohammadi, F. Raeisi Gahrooee,
Volume 7, Issue 4 (1-2004)
Abstract
Knowledge of the spatial dependency of soil properties, sensitive to grazing systems, is important from an ecosystem protection point of view. In the current study, geostatistical methods and fractal concepts have been used in order to characterize the impact of long-term grazing exclusion on the spatial variability of some soil chemical parameters including organic matter, total nitrogen, available phosphorous, and available potassium in both ungrazed and grazed sites located in Sabzkuh region, Chaharmahal Bakhtiari Province. The spatial pattern of different variables was studied using variogram. The results indicate that spatial variability of soil parameters depends upon grazing history. The variogram of organic matter in grazed areas shows a linear behavior without reaching the sill variance while organic matter in the ungrazed area established a strong spatial structure. Moreover, available phosphorous in the grazed area had pure nugget variation. Variograms of total nitrogen and available potassium in both grazed and ungrazed areas showed spatial structure approximated by spherical model. However, the range of variograms in exclusion sites was twice that of the grazed area. The results of applying the fractal theory show that soil properties have fractional behavior since increasing the scale of study reveals more details. Moreover, calculated fractal dimension values from variograms of different variables were close to 2.0 although this index was usually greater in the grazed area than in the exclusion sites. The calculated fractal dimensions can be used as a proper indicator of describing the pattern of spatial variability and its complexity.
The effect of long-term irrigation with municipal treated wastewater on the saturated hydraulic conductivity of a silt loam soil and its estimation- a case study
H. Beigi Harchegani, G. Banitalebi, M. Ghobadinia,
Volume 21, Issue 1 (6-2017)
Abstract

Treated wastewater may influence soil structure, porosity and as a consequence, soil saturated hydraulic conductivity. This study aims to assess the effect of wastewater on saturated hydraulic conductivity; and to determine the suitable soil solids fractal dimension to incorporate into the pedotransfer function by Rawls et al (1993) for estimation of saturated hydraulic conductivity (Ks). Soil saturated hydraulic conductivity was measured by disc permeameter. Soil particle fractal dimension was calculated from linearized forms of mass- time, mass- diameter and mass- diameter as modified by Kravchenko- Zhang (1998) relations. Wastewater irrigation for 13 years increased the saturated hydraulic conductivity three times, from 7 mm/hour to 21 mm/hour, but longer application of wastewater did not further increase it. Rawls et al (1993) pedotransfer produced acceptable and relatively close saturated hydraulic conductivity values to that of disc permeameter when fractal dimension obtained from the linearized forms of mass- diameter and Kravchenko- Zhang relations were used. Therefore, Rawls et al (1993) pedotransfer was capable of reflecting the effect of wastewater application on soil saturated hydraulic conductivity.
 


Determination of Agricultural Sulfur Effects on the Soil Structure Using Fractal Geometery and Aggregate Stability Indices
A. Karami, K. Khavazi,
Volume 23, Issue 2 (9-2019)
Abstract
Due to unsuitable soil physical conditions, calcareous soils, and the existence of a huge amount of sulfur in the country, the study of sulfur effects on the soil structure and other soil properties is necessary. Therefore, the effects of different rates of sulfur including: 0, 750, 1500 and 3000 kg/ha, when accompanied by Halothiobacillus neapolitanus bacteria, on the soil properties in the corn-wheat rotation in two years were investigated. Parameters of soil pH, EC, sulphate, organic carbon, soil structure and wheat yield were measured. For the quantification of soil structure and quantity evaluation of sulfur effect on the soil structure, with measuring the aggregate size distribution, the mean weight diameter (MWD) and geometric mean diameter (GMD) of the aggregate indices, and the amounts of fractal dimension were determined. The r results indicated that with the progress of the experiment and further application of sulfur along with thiobacillus bacteria, aggregation and aggregate stability were increased. The effect of sulfur treatments on MWD and GMD was significant; based on quantification indices, it had 28 percent positive effect on the soil structure. Sulfur with 3 percent reduction of fractal dimension had a significantly positive effect on the soil structure. Application of sulfur decreased a small amount of soil pH and increased 12 percent of the soil EC and 40 percent of the soil sulphate. So soil structure improvement and reclamation of soil physical condition can be very effective on the soil conservation and sustainability of the production resources and the conservation of environment.

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