year 13, Issue 1 (Spring 2023 2023)
E.E.R. 2023, 13(1): 175-189 |
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Karimi M, Abbaspour A, Safari Y, Dorostkar V. The Influence of Slope and Position Aspects on the Important Properties of Soil in Kalpoosh Region, Shahrood. E.E.R. 2023; 13 (1) :175-189
URL: http://magazine.hormozgan.ac.ir/article-1-726-en.html
URL: http://magazine.hormozgan.ac.ir/article-1-726-en.html
Soil Science Department, Faculty of Agriculture, Shahrood University of Technology, Shahrood , yaser.safari@shahroodut.ac.ir
Abstract: (2343 Views)
1- Introduction
Identifying the accurate patterns according to which the important properties of soils are impacted by various factors considering the local situations would be a prerequisite for the precise estimation of soil behavior and site-specific management. Topographical conditions of any given area are among the main factors which influence the variations of soil attributes, especially in small spatial scales. The influence of topography and its different aspects may vary depending on the local situations and also on the interactions of its effects with other soil-forming factors. Slope length and width, slope position and aspect as well as slope gradient would be considered as the most important topographical conditions which influence soil properties. By now, the previous researches conducting relevant studies to the impact of these factors on soil quality in different regions of the world have reported some inconsistent results. The current study was carried out with the aim of investigating the influence of slope and position aspects on the soil quality considering the local situations by comparing the amounts of soil pH, organic matter (OM), available phosphorus (P), mean geometric diameter of soil aggregates (MGD), and water-dispersible clay (WDC) in the soils located in the south-facing and north-facing slopes in five different slope positions, including the summit, shoulder, backslope, footslope, and toeslope in the forests of Kalpoosh area, in the Northeast of Shahrood.
2- Methodology
Kalpoosh area, 173 kilometers far from Shahrood City towards the Northeast, has a semi-arid climate and experiences snowy and freezing winters followed by cool summers. The study area is located in 36° 32′ N and 56° 41′ E, with an average altitude of 1270 meters above sea level. The area under investigation is naturally covered with semi-dense forests that, in recent years, considerable parts of these forests have been partly destroyed and then assigned to rain-fed farming by the local farmers. For sampling, two slope aspects, including south-facing and north-facing were selected and the five main slope positions, including the summit, shoulder, backslope, footslope, and toeslope were separated. Then, surface soil samples (0 – 20 cm) were taken up from three different points which were two meters far from each other in every slope position, and each individual sample was considered as a replication. Accordingly, considering the two selected slope aspects, 30 samples were gathered and after being passed from a 2-mm sieve, their mentioned properties were measured using standard methods. The data were statistically analyzed by applying the Duncan test, and one-way ANOVA in SPSS software, and the relevant diagrams were plotted by applying Excel software.
3- Results
The results indicating the combined effects of slope aspects and positions were significant on soil pH, OM and MGD (P < 0.01). Furthermore, the soils on shoulder position in north-facing slopes had the highest pH (8.17), whereas the minimum pH (7.73) was observed in the soils located on toeslope in south-facing slopes. The highest soil OM content was found in backslope position in south-facing slopes (4.79 %) and the lowest OM content was observed in toeslope position in south-facing slopes (0.62 %). Similarly, the soils located on shoulder and backslope positions in south-facing slopes had the highest MGD (1.23 mm), whereas the soils located on summit position in north-facing slopes showed the lowest MGD (0.79 mm). On the other hand, in contrary to the most of previous researches, the amounts of OM (2.64 %), P (10.13 mg/kg), MGD (1.30 mm), and WDC (2.23 %), in south-facing slopes were relatively more favorable compared to their corresponding values in north-facing slopes (2.13 %, 8374 mg/kg, 0.95 mm, and 3.90 %, respectively). Sites on backslope had significantly more favorable soil properties than other sampling sites, probably because of a gentle slope and the semi-dense plant cover in these sites. Correlation analysis revealed a significant relationship among OM with P (0.49, P < 0.01) and equivalent calcium carbonates with MGD (0.37, P < 0.05). Accordingly, it seems that soil OM is the premier factor controlling P distribution in soil, and similarly, soil carbonates curb the flocculation and soil aggregate creation in the studied soils.
4- Discussion & Conclusions
Considering the fact that Iran is located in the northern hemisphere and as it is well documented in previous papers, it is anticipated that the soils on north-facing slopes would be more mature with more favorable attributes in comparison with south-facing slopes. Unlike this estimation, comparing almost all of the soil properties in the two different slopes indicated that aside from slope position, the soils located on south-facing slopes had more favorable properties compared to north-facing slopes. Considering that the area under investigation undergoes early coldness in fall as well as heavy snows, low soil temperature in north-facing slopes seemingly hinders plant growth and soil evolution. On the other hand, receiving more radiation, soils located on south-facing slopes can modify the impacts of early coldness so that they provide the appropriate temperature for plant growth and the development of soil-forming processes.
Keywords: Deforestation, Soil temperature, Topographical conditions, Soil forming factors, Soil quality.
Received: 2022/04/24 | Published: 2023/04/28
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