Effects of landscape positions on soil physicochemical properties at Shenkolla Watershed, South Central Ethiopia

Belayneh Bufebo,Eyasu Elias,Getachew Agegnehu

doi:10.1186/s40068-021-00222-8

Abstract

BackgroundUnderstanding the effects of landscape positions on soil physicochemical properties is crucial for improving the soil productivity and to ensure the environmental sustainability. Three land use types forest land, grazing land and cultivated land all within upper, middle and lower landscape positions were selected to determine the effects of landscape positions, land use types and their interaction effects on soil physicochemical properties. Twenty seven soil samples were collected from lower landscape, middle landscape and upper landscape positions at the depth of 0–20 cm in nine replications. In addition, undisturbed soil samples were taken using core sampler from each land use type under upper, middle and lower landscape positions for the ascertainment of bulk density and water retentive capacity. The analysis of variance (ANOVA) was applied to determine variations in soil parameters among landscape positions and land use types. A Generalized Linear Models (GLMs) analysis was conducted to determine the influence of independent (fixed) factors, on the soil properties (response variables). Treatment means comparison was determined using the Least Significant Difference (LSD) at 0.05 level of significances.ResultsThe result indicated that among the soil properties sand (p < 0.001), silt (p < 0.001), clay (p < 0.001), bulk density (p < 0.01), water holding capacity at FC (p < 0.001), water retention at PWP (p < 0.01), Available water content (AWC) (p < 0.01), soil reaction (pH) (p < 0.05), Soil organic carbon (SOC%) (p < 0.01), Total nitrogen (TN%) (p < 0.01), available phosphorus (p < 0.05) and CEC (p < 0.001) have shown a significant variation among the landscape categories. Similarly, variation of sand (p < 0.001), silt (p < 0.001), clay (p < 0.001), bulk density (p < 0.01), water holding capacity at FC (p < 0.001), water retention at PWP (p < 0.001), Available water content (AWC) (p < 0.01), soil reaction (pH) (p < 0.01), SOC (p < 0.01), TN (p < 0.001) available phosphorus (AP) (p < 0.001) and CEC (p < 0.001) were also statistically significant among the land use types. Moreover, lower landscape position and forest land had high mean value of SOC, TN, AP, CEC, EB (exchangeable bases), and available micronutrients, whereas upper landscape position and intensively cultivated land had low mean value of SOC, TN, AP, CEC, EB (exchangeable bases), and available micronutrients.ConclusionLandscape positions, land use types and interaction effects of landscape position and land use types (LSP * LU) significantly affected soil properties. Soil with best quality was found in lower landscape position and forest land, while less quality of soil was found in upper landscape position and cultivated land. Thus, efforts should be made to improve the quality of soil under upper landscape position and cultivated land using biological and physical soil conservation measures.

Highlights

Understanding the effects of landscape positions on soil physicochemical properties is crucial for improving the soil productivity and to ensure the environmental sustainability
The results showed that sand content increased towards upper landscape position, and this is most probably resulting from the accelerated water erosion which selectively removes fine particles and leftover accumulation of sand in upper landscape position
The results of the study indicated that landscape positions, land use types and interaction effects of landscape positions and land use types (LSP * Land use (LU)) significantly affected soil texture, bulk density, water holding capacity at field capacity (FC) and permanent wilting point (PWP), water stable aggregate, soil pH, Soil organic carbon (SOC), Total nitrogen (TN), available phosphorus (AP), cation exchange capacity (CEC), EB (Ca, Mg, Na and K) and micronutrients

Summary

Introduction

Understanding the effects of landscape positions on soil physicochemical properties is crucial for improving the soil productivity and to ensure the environmental sustainability. Undisturbed soil samples were taken using core sampler from each land use type under upper, middle and lower landscape positions for the ascertainment of bulk density and water retentive capacity. One of the soils forming factors that influencing the distribution soil properties and water erosion is topography (Amuyou and Kotingo 2015; Khan et al 2013; Ziadat and Taimeh 2013). As a factor of soil formation, topography has influence on soil chemical and physical properties and affects the pattern of soil distribution over landscape even when the soils are derived from the same parent material (Lawal et al 2014). According to (Musa and Gisilanbe 2017) differences in soil properties due to slope gradient result in detachment, transportation and accumulation of soil materials. As a consequence of this process, different slope gradients may show different soil properties (Wang et al 2001)

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Conclusion