soil degradation 1 corinne waelti, seecon international gmbh

Soil Degradation

Soil Degradation

1

Corinne Waelti, seecon international gmbh

Soil Degradation

Find this presentation and more on: www.ssswm.info.

Copy it, adapt it, use it – but acknowledge the source!Copyright

Included in the SSWM Toolbox are materials from various organisations and sources. Those materials are open source. Following the open-source concept for capacity building and non-profit use, copying and adapting is allowed provided proper acknowledgement of the source is made (see below). The publication of these materials in the SSWM Toolbox does not alter any existing copyrights. Material published in the SSWM Toolbox for the first time follows the same open-source concept, with all rights remaining with the original authors or producing organisations.

To view an official copy of the the Creative Commons Attribution Works 3.0 Unported License we build upon, visit http://creativecommons.org/licenses/by/3.0. This agreement officially states that:

You are free to: • Share - to copy, distribute and transmit this document • Remix - to adapt this document. We would appreciate receiving a copy of any changes that you have made to improve

this document.

Under the following conditions: • Attribution: You must always give the original authors or publishing agencies credit for the document or picture you are

using.

Disclaimer

The contents of the SSWM Toolbox reflect the opinions of the respective authors and not necessarily the official opinion of the funding or supporting partner organisations.

Depending on the initial situations and respective local circumstances, there is no guarantee that single measures described in the toolbox will make the local water and sanitation system more sustainable. The main aim of the SSWM Toolbox is to be a reference tool to provide ideas for improving the local water and sanitation situation in a sustainable manner. Results depend largely on the respective situation and the implementation and combination of the measures described. An in-depth analysis of respective advantages and disadvantages and the suitability of the measure is necessary in every single case. We do not assume any responsibility for and make no warranty with respect to the results that may be obtained from the use of the information provided.

Copyright & Disclaimer

Soil Degradation


Contents

1. Introduction

2. Four Types of Soil Degradation

3. Human Causes of Erosion

4. Controlling Erosion

5. Conclusion

6. References

3

Soil Degradation


The overall Problem

Soil degradation is an increasing global process affecting mainly arid and semi-arid zones in sub-Saharan Africa. Principal forms are the depletion of nutrients and soil organic matter and erosion.

The negative impacts of soil degradation may lead to partial or complete loss of the soil’s current and/or future productive capacity. Soil degradation can be a result of both natural hazards and unsuitable land use.

4

1. Introduction

What is soil degradation?Process by which one or more of the potential ecological functions of the soil are harmed or destroyed.

Soil Degradation


5

1. Introduction

Four Types of Soil Degradation

Soil degradatio

n

Water erosion Wind erosion

Chemical deterioration

Source: PLANT and SOIL SCIENCES ELIBRARY (2005)

Source: RITTER (2003)

Source: http://www.unibas.it/desertnet/dis4me/issues/issue_degradation.htm

Physical deterioration

Source: http://www.extension.iastate.edu/CropNews/2009/0430alkaisih

anna.htm

Soil Degradation


6

1. Introduction

A global Problem: Human induced Soil Degradation

ISRIC et al. (1996)

Soil Degradation


7

2. The Four Types of Soil Degradation

Water Erosion (1/2)

Factors influencing water erosionRainfallThe impact of raindrops on the soil surface can break down soil aggregates and disperse the aggregate material over the surface.

Soil typeSoils with faster infiltration rates, higher levels of organic matter and improved soil structure have a greater resistance to erosion.

Slope gradientSteeper and longer slopes of a field lead to greater amount of soil erosion by water.

Soil usePlants may protect the soil from raindrop impact and splash, slow down the movement of surface runoff and allow infiltration of excess surface water.

Soil particles, which are either detached by splash erosion or by the effect of running water.

BALLAYAN (2000) and INFONET-BIOVISION (2010)

Soil Degradation


8


Water Erosion (2/2)

Types of water erosionSheet erosionRemoval of a fairly uniform layer of soil from an entire surface area.

Rill erosionSmall channels running over the soil surface causing deeper incision of the channels into the surface.

Gully erosionRills flowing together form larger streams and tend to become deeper with successive flow of water.

Bank erosionWater cutting into the banks of streams and rivers.

BALLAYAN (2000)

Soil Degradation


9


Wind Erosion

SHELTON (2003)

Factors influencing wind erosionSoil erodibilityFine and medium soil particles can be transported over great distances. Coarse particles can be blown along the surface.

Soil surface roughnessSoil surfaces that are not rough or ridged offer little resistance to the wind.

ClimateSoil moisture levels can be very low at the surface during periods of drought, thus releasing particles for transport by wind.

Vegetative coverThe lack of permanent vegetation cover may lead to extensive erosion by wind as loose, dry and bare soil is most susceptible.

Soil Degradation


10


Chemical Deterioration

FAO/AGL (2000)

Effects

•Loss of nutrients and organic matter leading to reduced plant growth

•Salinisation

•Acidification

•Soil pollution

•Fertility decline

Typical causes

•Municipal or industrial wastes

•Oil spills

•Excessive use of fertiliser, herbicides and insecticides

•Release of radioactive materials

•Airborne pollutants

Soil Degradation


11


Physical Deterioration

FAO/AGL (2000)

Effects

•Soil crusting

•Increased runoff

•Decreased infiltration of water into the soil

•Prevention and inhibition of plant growth

•Higher susceptibility to other forms of degradation

Typical cause

•Compaction through heavy machines or animals

Soil Degradation


Human Actions leading to Soil Degradation

• Poor agricultural practices

• Exposing soil on slopes

• Removal of forest vegetation

• Overgrazing

• Altering the characteristics of streams, causing bank erosion

• Reducing evapotranspiration losses due to vegetation removal

• Producing impervious surfaces such as roads and footpaths causing increased runoff into streams

• Overexploitation of groundwater

12

3. Human Causes of Erosion

ACS DISTANCE EDUCATION (2009)

Soil Degradation


The most common Control Methods

• Cover materials (e.g. plants)

• Improved crop production techniques (e.g. organic fertiliser, type of irrigation method)

• Ploughing to destroy rills and contour planting

• Terracing

• Careful selection of land use practices

• Conservation tillage methods

• Armouring of channels to prevent bank erosion

• Wind breaks

• Ploughing into clod sizes too big to be eroded / Ploughing into ridges

Sustainable Agriculture / Land Management

13

4. Controlling Erosion

ACS DISTANCE EDUCATION (2009)

Soil Degradation


Sustainable Land Management is crucial

14

5. Conclusion

World population

Available land

Food production

Food demand

No sustainable land managementChanges with sustainable land management

Degraded soil

Sustainable land

management

Soil Degradation


15

6. ReferencesACS DISTANCE EDUCATION (Editor) (2009): Soil Degradation. Stourbridge: ACS Distance Education. URL: http://www.acsgarden.com/articles/other-gardening/soil-degradation.aspx [Accessed: 05.06.2012].

BALLAYAN, D. (2000): Soil Degradation. ESCAP environment statistics course. Rome: FAO. URL: www.unescap.org/stat/envstat/stwes-04.pdf [Accessed: 06.06.2012].

FAO (Editor), AGL (Editor) (2000): Management of Degraded Soils in Southern and eastern Africa (MADS-SEA-Network). Rome: FAO.

INFONET-BIOVISION (Editor) (2010): An Introduction to soil degradation. Zurich: Biovision. URL:http://www.infonet-biovision.org/default/ct/184/soilManagement [Accessed: 05.06.2012].

ISRIC (Editor), UNEP (Editor), FAO (Editor) (1996): Human Induced Soil Degradation. Rome: World Food Summit. URL: www.fao.org/docrep/003/w2612e/w2612eMap12-e.pdf [Accessed: 06.06.2012].

PLANT (Editor), SOIL SCIENCES ELIBRARY (Editor) (2005): Picture of Gully Plug Erosion. University of Nebraska-Lincoln. URL: http://plantandsoil.unl.edu/croptechnology2005/pages/index.jsp [Accessed: 08.10.2010].

RITTER (2003): The Physical Environment. An Introduction into Physical Geography. URL: http://www4.uwsp.edu/geo/faculty/ritter/geog101/textbook/title_page.html [Accessed: 06.06.2012].

SHELTON, I. J. (2003): Soil Erosion – Causes and Effects. Ridgetown College of Agricultural Technology. Ontario Institute of Pedology. URL: http://omafra.gov.on.ca/english/engineer/facts/87-040.htm [Accessed: 05.06.2012].

Soil Degradation 16

“Linking up Sustainable Sanitation, Water Management & Agriculture”

SSWM is an initiative supported by:

Created by:

soil degradation 1 corinne waelti, seecon international gmbh

Documents

soil erosion

soil surface

soil aggregates

soil particles

soil organic matter

soil type soils

improved soil structure

soil sciences elibrary