Effect of Slope Positions on Properties of Soils of some Forest reserves in South-West Nigeria

2021 ◽  
pp. 18-24
Author(s):  
Alabi K. O.

Topography has an influence on soil erosion and consequently on the properties of soils. The effect of slope position on soil properties is of great importance in soil suitability assessment. This study assessed the effect of topographic position on the characteristics of soil of basement complex rocks derived soils under Teak (Tectona grandis) and Gmelina (Gmelina arborea) plantations in Osun sacred grove, Onigambari and Omo forest reserves situated within South-West Nigeria. Three soil profiles were dug in each landuse type, sited at the upper, middle and lower slope positions along a toposequence. Soil samples were collected according to their pedogenetic horizons and were analyzed using standard methods. Results showed variations in colour, depth of soil profile, soil structure, texture, drainage and soil consistence. The high sand content dominated the particle size fraction in all the soils formed from the three locations, and base saturation was rated very high with values >90% irrespective of the toposequence or slope position. The result of correlation analysis between slope position and content of N, P, K and CEC showed a significant relationship irrespective of locations with N(r = 0.019< 0.05) respectively. Despite variation in soil properties as influenced by topography, the studied soils can sustain the current land use type. It was concluded that soils on different topographic positions should be managed differently.

2021 ◽  
Author(s):  
Melaku Alene Retta ◽  
Hailu Kendie Addis ◽  
Tesfaye Feyisa Beyene

Abstract Background: The Ethiopian highlands are affected by soil loss caused by soil erosion resulted in soil properties deterioration. To reverse this, different soil and water conservation (SWC) measures were spatially practiced; however, the effect of SWC and slope gradient on soil properties is not studied well in the area. Hence, this study was conducted to evaluate the effects of SWC and slope gradient on selected soil physicochemical properties at Dawnt watershed, North-western Ethiopia. The treatments were a combination of four different SWC measures with three slope gradients replicated at three sites. Disturbed and undisturbed soil samples were collected from 0-20cm soil depth and physicochemical properties were determined following standard laboratory procedures. Results: The lab results depict that sand, bulk density, moisture, particle density, porosity, pH, organic carbon (OC), cation exchange capacity (CEC), total nitrogen, and available phosphorus were significantly (P<0.05) affected by SWC measures and slope gradient. High OC (2.44%), CEC (45cmol (+) kg-1), and moisture (19.55%) were obtained from Stone-Faced Soil Bund stabilized with Grass (SFSBG) and high available phosphorus (7.83ppm) from Soil Bund (SB) while lower bulk density (1.13gm/cm3) from SFSBG. Additionally, higher clay (41.67%) and moisture (19.81%) and lower bulk density (1.14g/cm3) were obtained from the lower slope. Higher pH (6.75) and OC (2.89%) were recorded at lower slope under SFSBG and lower pH and OC (6.03 and 1.02%) at the upper slope with non-conserved. Soil chemical properties, except available potassium, were increased down the slope.Conclusion: The interactions of slope position and SWC measures affect soil texture; pH, organic carbon, and available phosphorus but do not affect soil bulk density, moisture content, particle density, total porosity, cation exchange capacity, total nitrogen, and available potassium. In generally, the soil properties were improved through integrating conservation practices with multipurpose grass species across the study watershed. Therefore, in the study watershed and other similar agro-ecologies, farmers should use integrated SWC measures to avert the rainfall-driven soil nutrient loss.


2021 ◽  
Vol 13 (8) ◽  
pp. 4288
Author(s):  
Siyue Sun ◽  
Guolin Zhang ◽  
Tieguang He ◽  
Shufang Song ◽  
Xingbiao Chu

In recent years, soil degradation and decreasing orchard productivity in the sloping orchards of the Three Gorges Reservoir Area of China have received considerable attention both inside and outside the country. More studies pay attention to the effects of topography on soil property changes, but less research is conducted from the landscape. Therefore, understanding the effects of landscape positions and landscape types on soil properties and chlorophyll content of citrus in a sloping orchard is of great significance in this area. Our results showed that landscape positions and types had a significant effect on the soil properties and chlorophyll content of citrus. The lowest soil nutrient content was detected in the upper slope position and sloping land, while the highest exists at the footslope and terraces. The chlorophyll content of citrus in the middle and upper landscape position was significantly higher than the footslope. The redundancy analysis showed that the first two ordination axes together accounted for 81.32% of the total variation, which could be explained by the changes of soil total nitrogen, total phosphorus, total potassium, available nitrogen, available potassium, organic matter, pH, and chlorophyll content of the citrus. Overall, this study indicates the significant influence of landscape positions and types on soil properties and chlorophyll content of citrus. Further, this study provides a reference for the determination of targeted land management measures and orchard landscape design so that the soil quality and orchard yield can be improved, and finally, the sustainable development of agriculture and ecology can be realized.


2012 ◽  
Vol 92 (5) ◽  
pp. 923-931 ◽  
Author(s):  
H. J. Beckie ◽  
S. Shirriff

Beckie, H. J. and Shirriff, S. 2012. Site-specific wild oat ( Avena fatua L.) management. Can. J. Plant Sci. 92: 923–931. Variation in soil properties, such as soil moisture, across a hummocky landscape may influence wild oat emergence and growth. To evaluate wild oat emergence, growth, and management according to landscape position, a study was conducted from 2006 to 2010 in a hummocky field in the semiarid Moist Mixed Grassland ecoregion of Saskatchewan. The hypothesis tested was that wild oat emergence and growth would be greater in lower than upper slope positions under normal or dry early growing season conditions. Three herbicide treatments were imposed on the same plots each year of a 2-yr canola (Brassica napus L.) – wheat (Triticum aestivum L.) sequence: (1) nontreated (weedy) control; (2) herbicide application to upper and lower slope positions (i.e., full or blanket application); and (3) herbicide application to lower slope position only. Slope position affected crop and weed densities before in-crop herbicide application in years with dry spring growing conditions. Site-specific wild oat herbicide application in hummocky fields in semiarid regions may be justified based on results of wild oat control averaged across slope position. In year 2 of the crop sequence (wheat), overall (i.e., lower and upper slope) wild oat control based on density, biomass, and dockage (i.e., seed return) was similar between site-specific and full herbicide treatment in 2 of 3 yr. Because economic thresholds have not been widely adopted by growers in managing wild oat, site-specific treatment in years when conditions warrant may be an appropriate compromise between no application and blanket herbicide application.


2012 ◽  
Vol 92 (4) ◽  
pp. 665-672 ◽  
Author(s):  
Leila Nazmi ◽  
Hossein Asadi ◽  
Ruzanna Manukyan ◽  
Hamdollah Naderi

Nazmi, L., Asadi, H., Manukyan, R. and Naderi, H. 2012. Influence of tillage displaced soil on the productivity and yield components of barley in northwest Iran. Can. J. Soil Sci. 92: 665–672. In hilly landforms subject to long-term cultivation, erosion has denuded the upper slope positions of topsoil, and accumulated topsoil in the lower slope positions. Slope gradient and position effects aggregation processes, which in turn impact soil productivity. A field experiment was conducted to assess the tillage-induced soil displacement and its effects on the soil properties and barley (Hordeum vulgare var. Sahand) biomass production for three different landscapes. The study was conducted on a hill slope seeded with barley (1.4–10.1° slope) located in the Mollaahmad watershed of the Ardabil province in northwestern Iran. For this purpose, soil samples were collected from four slope positions in a grassland as well as an agricultural field (dryland). A field experiment was conducted to evaluate the effects of slope gradient and position on barley growth and soil quality. Soil generally had lower organic carbon, available phosphorus, calcium carbonate equivalent, soil water content and mean weight diameter of soil aggregates in the farmland than the grassland, and in the upper slope positions than in the lower slopes. Significantly higher barley growth indices were associated with lower slope positions. Agronomic productivity of the soil was lowest for landscapes with the highest slope gradient. The relationships between tillage erosion and yield components were found to be significant. Spike weight and slope position had the largest contribution for the explanatory capacity of canonical variables (tillage erosion and yield components) estimated when compared with other parameters (slope gradient, dry matter, spike number, grain yield and 1000-grain weight). The findings in this study can be used as a tool to assist farmers, soil and water conservationists, and other policymakers in decision making regarding the use of lands.


2001 ◽  
Vol 48 (2) ◽  
pp. 133-150 ◽  
Author(s):  
F Moreno ◽  
F Cabrera ◽  
E Fernández-Boy ◽  
I.F Girón ◽  
J.E Fernández ◽  
...  

1986 ◽  
Vol 16 (3) ◽  
pp. 624-629 ◽  
Author(s):  
S. J. Tajchman ◽  
C. M. Minton

Daily and seasonal variations in soil temperature at various topographic positions in a forested catchment are compared. The experimental sites were designed as ridgetop, north-facing lower slope, south-facing lower slope, and southwest-facing slope. On sunny days during the growing season, the surface temperature had the greatest amplitude (7.8 °C) at the south-facing upper slope and the smallest amplitude (4.0 °C) at the north-facing slope; the remaining sites were intermediate. The maximum surface temperature was observed in the afternoon at all sites. With increasing depth, daily soil temperature ranges diminished and, below 10 cm depth, they were less than 1 °C. Under overcast conditions, daily soil temperature fluctations lessened. For individual months, the mean temperatures of the 2–30 cm soil layer generally varied among all sites by less than 1 °C and never the difference exceeded 1.8 °C. The surface temperature variations and their differences among sites appear to be the most distinguished feature of the soil thermal regime and they seem to be aspect related.


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