WOSSAC®

World Soil Survey Archive and Catalogue

Welcome to WOSSAC

Overview of Niger materials

NigerThe WOSSAC archive has a limited number of documents from Niger. However, one project has generated a significant number of documents and an excellent map series and this provides a useful description of an area of 8,000 sq. km. in the east of the country close to the border with Nigeria. A useful map within the report shows the area as defined by approximately 11.5 deg N to 13.5 N. The area is some 225 km in length and is a long narrow band following old drainage lines which are tributaries of the River Niger.

The documents held by WOSSAC are two reports in French and one translation in English (WOSSAC #9102). There are two accompanying map volumes WOSSAC #9104 (Maps 1-10) and WOSSAC #9105 (Maps 11-20). The Report is entitled, Project de Mise en Valeur Du Dallol Maoure Etudes Pedologiouesi> (WOSSAC #9102). Therefore there are 20 maps-all coloured- and this note provides a guide to the documents especially the useful maps. These were all produced by HTS in September 1969. The survey documentation is structured in three levels.

  • Two maps of the total area at a reconnaissance scale of 1:200,000;
  • A comprehensive mapping series at semi-detailed level of 1:25,000;
  • One at 1:5000-a detailed survey.

The basis of the survey is to explore the usefulness of the landscape features described as a ‘dallol’, which is a former river channel cut into a plateau with laterite soils. These channels are now choked by sand and do not carry water, except in exceptional floods. The channels are often waterlogged and are sometimes described as a fadama. Given this landscape history the survey makes use of easily understood landscape units in defining mapping units, e.g. depressions.

The Niger Classification system

The map series is best understood as three series recording soils; land capability; and finally suitability for irrigation. The framework for the classification is well described within the reports e.g. Section 3.2 describes the Principle Soil Types, using FAO terminology. The Table below sets out the structure of the mapping. The best introduction to the map series is to examine Map 3 first as this provides a Location Diagram, showing all the semi-detailed areas mapped. The Table A. below lists these named locations within the survey area, with an indication of the appropriate map, and Table B, lists the map scales with some notes.

Area

Soil Map #

Land Class Map #

Irrigation Suitability #

Dallol Tuli

4

 

20

Kiese

4

10

16

Fadama

5/8

14

20

Guecheme

5

11

17

Lagere

3

9

15

Gueza

3

 

15

Nord de Gaya

6

 

18

Sud de Gaya

7

13

 

Bengou

8

14

20

 

 

 

 

Map #

Scale

Location

Map Type

Note

1

200,000

All area

Soils and PM

Seven PM types e.g. wet or gleyed soils

2

200,000

 

Land capability

 

3

25,000

Dallol Tuli

Soils

Also 400,00, location diagram

4

25,000

Kiese

Soils

 

5

25,000

Guecheme

Soils

 

6

25,000

North Gaya

Soils

 

7

25,000

South Gaya

Soils

 

8

5000

Tuli

Soils

 

9

25,000

Lagere

Land class

Repeat of #4, with location

10

25,000

Kiese

Land class

 

11

25,000

Guecheme

Land Class

 

12

25,000

Gaya  N

Land class

 

13

25,000

Gaya  S

Land class

 

14

25,000

Bengue/Fadama

Land class

 

15

25,000

 

Irrigation porential

 

16

25,000

 

irrigation

 

17

25,000

 

Irrigation

 

18

25,000

 

irrigation

 

19

25,000

 

Irrigation

 

20

5,000

Tuli

Irrigation Potential

Four class systems of classes


The land classification demarcates five classes and classifies these to the sub-class level with qualifying notation such as d-drainage; t-topography; and s-soil, which show the limiting factors. In general class 4 soils have limited arable use, mostly due to their sandy textures.

The irrigation classification is mostly as Class 3-that is coarse textured and suitable only for irrigation by sprinkler or piped.

The report gives 65 sets of chemical analysis and 15 soil profiles are described.

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