Running Head: Soil Profile Practical 1

 

Running head: SOIL PROFILE PRACTICAL

Soil Profile Practical An Assignment Submitted by Name of Student Name of Establishment

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SOIL PROFILE PRACTICAL

2 Soil Profile Practical

Introduction

Chromosols soils occur in most areas and are common in the wheat belt of New South Wales. Nevertheless, these large areas of the grass and shrub woodlands are affected by gully erosion, and it has a negative influence on the crop farming and grazing of the region. Therefore, it is essential to understand the causes of the gullies formation and find the way to prevent their spreading. Method

The first step involved identifying a site in the south-eastern uplands of Australia. This region was chosen because of a well developed soil profile that could provide an understanding of how the profile related to the gully erosion. The sample of soil was randomly collected to be tested for such parameters as boundaries, colour, stickiness, and behaviour under an applied shear force. Description of the Site Chosen

The chosen site is located in Belhaven, Puddledock, about 12 kilometres from the New England. The soil of the site has moderate agricultural potential and water-retaining capacity. The general area is a hilly country of natural grass and shrub, as well as pastures, orchards, vineyards and lands under crop, yet the landscape is abundant of medium size ravines containing the rocky layers at the bottom. There is no or insignificant evidence of wind erosion but water erosion is significant. The average depth of gullies is from 1.5 to 3 meters; extensive presence of such gullies is observed throughout entire southeast region of Australia. The soil of chosen site is characterized by high level of partially stabilized erodibility and negligible level of salinity.

 

SOIL PROFILE PRACTICAL Soil Profile Description and Classification

Table 1: Soil Profile: Mottled, Brown Chromosols, medium, slightly gravelly, loamy/clayey, loamy/clay ey, shallow Soil horizon

Summary description

A1 (0-20 cm)

Dark, strong brown, distinct distinct (7,5 YR 5/6). Sharp even boundary. Weak Crumbly consistence. No water. Texture: fine sand, clay loam. Normal plastic. Structure: Single grained, granular (2-5 mm). Slight stickiness and porosity less than 10%. Layer consists of roots that longer than 5 mm from 10 to 50%. Layer also consists of subrounded stones with size 2-6 mm, less than 10%.

A2 (20-25 cm)

Pale, yellowish yellowis h brown, distinct distinc t (10 YR 5/4). Clear even boundary. Moderate Crumby consistence. No ground water. Texture: medium loam, fine sandy. Normal plastic. Structure: single grained, crumb (less than 2 mm). Moderate stickiness and porosity from 2 to 10 mm. No roots. Angular stones, size from 6 to 20 mm, frequency - less than 10%.

B2 (25 +)

Pale, brownish yellow, distinct (10 YR 6/6). Very Strong, plastic consistence. No ground water. Texture: Fine Heavy Clay. Normal plastic. Structure: massive, lenticular (20 – 50 mm). Stickiness – much. Porosity is less than 2 mm. No roots. Angular stones from 20 to 60 mm.

Mottled sodic Duplex Soils, parent material is Devonian granitic rocks, according to Northcote classification (1979) – class Dy 3.41. The Great Group Hypercalcic [CQ] approximately corresponds to Class III A of Wetherby and Oades (1975).

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SOIL PROFILE PRACTICAL Chromosols have a sudden increment of clay content in deeper horizons of the soil profile. Generally, they are notable by law or medium level of sodium and being slightly acidic in the subsoil. These soils may hinder internal drainage. Strong texture contrast of the A and B horizons is the fundamental feature of Chromosols; in upper B horizons, they are not strongly acidic or sodic, and it is distinguished them from other texture contrast soils. Natural Chromosols have favorable chemical and physical properties, however, long period of agricultural activity affected their surface layers and led them to structural degradation. (Raymond Isbell, 2002) Brown Chromosols are characterized by brown clay or clay loam that concentrated in B horizons. Parent materials are consisted of sediments and wide range of rocks. Brown Chromosols usually have better internal drainage than other types of Chromosols. Subsoil Ph varies widely from neutral to slightly acid. Lower B horizons sometimes became sodic. Brown Chromosols have an inclination to soil acidification and declination of the soil structure; they are moderately susceptible to water erosion. (Raymond Isbell, 2002) Types of Gully Erosion

The gullies identified in the region have four key types with distinct characteristics. The first form, the amphitheatre, is observed on highly dispersible soils that are known for their high carbonate content. These gullies are also observed on both proximal and distal margins of the alluvial ridges (Landloch, ( Landloch, 2003). 2003). The second type of gully erosion is the Continuous Scarp Front; it is observed running parallel to rivers in the south-eastern uplands and appears to be a matured version

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SOIL PROFILE PRACTICAL of the amphitheatre in which several amphitheatres coalesce to form one giant gully. Continuous Scarp Front is observed in areas with mainly sodic soils. The third type of gully erosion has the dendritic form. The main gully complex stem forms a network of drainage channels that extend to other previous flood plain levels. These channels are usually separated by the interfluve. This form has calcrete 1987). ). nodules that are not as evident as those in the amphitheatre (Crouch, (Crouch, 1987 The fourth form of gully erosion is the linear form of erosion. This type of gully erosion is associated with the anthropogenic disturbances. The depth of erosion depends NSW DPI, 2007). on site-specific circumstances ((NSW 2007). Describing the Gully erosion of the chosen site

The reason of gully erosion of the site that was chosen for this practical is the linear erosion; it is characterized by elongate planform of the gullies. This type of gully erosion is associated with human activities and anthropogenic disturbances such as roads, cultivation and grazing. The soil of the chosen site is characterised by high level of erodibility. Therefore, the particles of the soil can be torn away by applying moderate force. The fact that the site is located on the open territory as well as poor ground cover is notably contributed into gullies’ formation. Grass and shrubs do not have developed enough roots’ system to make soil stronger. Roads and other forms of pathways are responsible for linear erosion because their pressure impacts on the soil, which weakens its ability to stick together. At first, the impact is not serious, but when it is repeated, it produces trenches in which water pathways can form. When water uses such linear trenches as preferred pathways, the trenches undergo linear gully erosion ( Valentin, Poesen, & Yong, 2005). 2005).

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SOIL PROFILE PRACTICAL Biophysical Processes Responsible for Soil Erosion

Basal sapping is the major cause of most forms of gully erosion. This process leads to the failure of block of masses, which then results in trenches. This occurs after Boucher & Powell, 1994 1994). ). After flooding has taken place on any given piece of land ((Boucher heavy rainfall, water on the surface flows down the slope along certain preferred paths. As the water flows down the paths, it carries particles such as stones and pebbles. When these pebbles flow down the slope, they scour the surface and lose the soil. Continuous scouring by the pebbles within the floodwater erodes the soils, and the eroded particles are transported down the slope in the form of alluvial particles. These are carried out to the rivers and other water bodies. When this process is repeated over time, the preferred flow pathways enlarge in width and depth, thus forming gully erosion ( Valentin, Poesen, & Yong, 2005). 2005). How to Manage Gully Erosion in Australia

The measures include building terraces to slow down the speed of water, thus reducing its eroding power. It is essential for farmers to engage in tree planting especially on sloped uplands ((National National Land and Water Resources Audit, 2001 2001). ). The welldeveloped root system of the trees may enhance the entrapment of the soil. They can make relatively harder for the floods to carry the soil particles away ( Valentin, Poesen, & Yong, 2005). 2005). Government should support encouraging the adoption of appropriate grazing management policies that would result in minimised soil erosion. For example, the sloppy uplands should be covered with pastures that would then be used to feed the livestock.

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SOIL PROFILE PRACTICAL

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The pasture would also prevent the other forms of erosion that usually encourage, or develop into, gully erosion. Conclusion

The control and prevention of gully erosion and gully rehabilitation techniques are primary task in effective catchment management. Such heightened attention placed on the influence of gully erosion because of

deterioration deteriorati on of of the soil properties and, as a

consequence, abrupt reduction fertile soils. By analysing a number of factors such as soil profile, elevation, geology and land usage the scientists are able to assess danger of gully erosion in potentially unfavourable areas. This assesment makes possible the implementation of preventative measures to reduce and prevent gully erosion spreading. Sometimes, stabilized gully erosion is better to leave alone, because intervention may disturb dispersive soils and reactivate the gully erosion spreading. However, the samples of soil from chosen site demonstrated the high erodibility of the soil, and that mean that gully is active. Therefore, considering type of soil the best decision to prevent the further spreading of gully is adequate vegetation. First of all, diverse layers of trees, shrubs and grass cover impede the force of raindrops that strike the ground and decelerate the speed of surface runoff. Second of all, plant's roots hold the t he soil together and improve the soil physical properties such as porosity and stability. Thus, this practical demonstrated not only how to define the soil profile, but what conclusions can be made based on this soil profile.

 

SOIL PROFILE PRACTICAL

8 References

Raymond Isbell (2002) The Australian Soil Classification (revised edition). CSIRO PUBLISHING, PUBLISHI NG, 152 p.  p.  Boucher, S. C. (2007). Gully erosion. Victoria: Monash University. Boucher, S. C., & Powell, J. M. (1994). Gullying and tunnel erosion in Victoria.  Australian Geograph Geographical ical Studies, 32, 17–26.

Brady, N.C., & Weil, R.R. (2008). The Nature and Properties of Soils. New Jersey: Prentice Hall. Brierley, G. J., & Fryirs, K. A. (2005). GEOMORPHOLOGY GEOMORPHOLOGY AND RIVER MANAGEMENT: APPLICATIONS OF THE RIVER STYLES FRAMEWORK . Malden, MA: Blackwell. Crouch, R. J. (1987). The relationship of gully sidewall shape to sediment production.  Australian Journal of Soil Soil Research Research, 25(4), 531–539.

Fisher, R.F., & Binkley, D. (2000). Ecology and and Management Management of Forest Forest Soils. 3rd Edition. New York: John Wiley & Sons, Inc. Hooke, J., & Mant, J. (2002). Morpho-dynamics of ephemeral streams. In Bull, L. J., & Kirkby, M. J. (Eds.), Dryland Rivers: Rivers: Hydrology Hydrology and Geomorpho Geomorphology logy of Semiarid Channels. West Sussex, UK: John Wiley and Sons.

Landloch, D. (2003). A Geomorphic Geomorphic System for for Gully Assessment  Assessment , Darling Heights, Queensland: Landloch Pty Ltd. National Land and Water Resources Audit. (2001). Australian agriculture agriculture assessme assessment nt 2001. Canberra: Land and Water Australia.

 

SOIL PROFILE PRACTICAL NSW DPI. (2007). Soil erosion solutions, Fact sheet 5: Gully erosion. New South Wales, Australia: Wollongbar. Prosser, I. P., & Slade, C. J. (1994). Gully formation and the role of valley-floor vegetation, south-eastern Australia. Geology, 22, 1127–1130. Olley, J. M., & Wasson, R. J. (2003). Changes in the flux of sediment in the Upper Murrumbidgee catchment, south-eastern Australia, since European settlement. (16), 3307–3320.  Hydrological  Hydrolo gical Processes Processes, 17 (16), Smith, C. J. (2003). Targeting gully erosion at a catchment scale. Conference Proceedings: International Congress on Modelling and Simulation, 1, 302–307.

Torri, D., & Borselli, L. (2003). Equation for high-rate gully erosion. Catena, 50(2-4), 449–467. Valentin, C., Poesen, J., & Yong, L. (2005). Gully erosion: Impacts, factors and control. Catena, 63, 132–153.

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