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University of the PhilippinesCollege of Forestry and Natural ResourcesInstitute of Renewable Natural Resources

College, Laguna 4031

SFI 10

ELEMENTARY FOREST SOIL CONSERVATION

Name: Chiaw Yuen B. LooStudent No: 2011-97347

Course and Year: CertFor 1

st

Sem 2012- 2013

Exercise No. 4

VISUAL SOIL EROSION INDECES

INTRODUCTION

The occurrence of soil erosion in the field may be as certained by noting observablesigns of features. These include the following:

1. Hills - small channels usually a few inches deep, that are formedby water running down the slope. They are easily obliterated by tillage operations.

2. Gullies are deep and channels ranging from 1-2 ft to as much as 100 ft, andcannot be obliterated by normal tillage operations.

3. Turbid surface runoff is observed by noting the color of water in the rivers andwaterways after a heavy rain. Turbid or brown streamwater suggests the occurence ofconsiderable erosion in the upland watershed.

4. Erosion pedestals - as fine soil materials are eroded away, heaviermaterials like stones and gravel remain on the soil surface.

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5. Erosion pavements - perched stones and pebbles have protected the soildirectly underneath them from erosion, thus forming "pedestals" of elevated soilsurrounded by eroded areas.

6. Soil accumulation at the base of trees in the lower part of the slope suggests the

transport of soil materials by erosion from the upper part of the slope.

7. Exposed roots - due to the removal of soil material roots which havebeen buried in the soil materials by erosion from the upper part of the slope.

8. Unscorched collars - in previously burned areas evidence of erosion existas root collars previously under the ground and have thus escaped burning becomeexposed.

9. Exposed parent material - with the removal of topsoil and subsoil or in very thinsoils of sloping areas, severely eroded areas exhibit exposed parent materials.

10. Bare areas which have no protective vegetative cover as in newly cultivatedfields, roadcuts and clean cropped lands are exposed to the impacts of the raindropsand are most likely to have high soil erosion rates, especially if the areas are steep.

11. Slides of rocks soils and sands - gradual and sudden soil movementssuch as in landslides and landstips occur in steep areas where the soil material is notfirmly anchored to the underlying rocks.

OBJECTIVES

This exercise is conducted to enable the students to:

1. Be familiar with the more common visual soil erosion indeces occurring in thefield.

2. Evaluate the soil erosion condition of an area by using visual soil erosionindeces.

METHODOLOGY

1. The instructor will explain the soil erosion indeces. Pictures and slides on theseindeces will be shown.

2. The class will be brought to an area where visual soil erosion indeces may befound. Locate and identify the various soil erosion indeces observed.

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These are pictures from the wonderful photo hike with our Sir Gascon :)

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