Table 2. Information needs in soil map.
16
S.No. Information Scale
Purpose
Remarks
1. Great group/their
association
2. Sub group/Family
association
3. Series association
4. Pure series
5. Pure series and
their phases
1:1 m National Atlas, reference for regional level
soil surveys, input for national projects like
IGBP and GCM
National organisations like
NATMO NBSS & LUP,
AIS& LUS
1:250,000 Planning for states or region, soil delineated for
possible use and not for management purpose,
tentative project site location
1:50,000 . District land use planning, Forest, Horticulture
at micro watershed level etc. Command areas
and pre-irrigation surveys, tentative site planning
and feasibility studies
1:25,000 Block/Mandal level planning and implementation
1:4,000 Project/site specific planning and implementation
State planning
Board/Dept.
DRDO, DPAP, JDA, ETC.
DRDO. DPAP, JDA. ETC.
DRDO, DPAP, JDA. ETC.
SOIL RESOURCE MAPPING
Soil map constitute an important component for
landuse planning. The scale of mapping, however, varies
for different purposes. A mapping scale of 1:1,000,000
is considered appropriate for national level mapping,
whereas at district level 1:50,000 scale of mapping is
operational. The requirements may reach to about
1:4,000 scale for farm level/microwatershed level (Table
1). The information needs also vary with different scales
(Table 2). A scale of 1:10,00,000 provides information
on great group and their association, these maps are used
for generating national atlas and act as reference for
regional level soil surveys, and provide inputs for
national/continental level studies (e.g. IGBP and GCM).
The state level mapping (1:250,000) exhibits subgroups
or family association whereas 1:50,000 mapping depicts
the association of series. Pure series are provided at
1:25,000 scale and used for Block/Mandal level
planning and implementation. The pure series and their
phases are included in detailed soil maps (1:4,000 scale)
which are used for project/site specific planning and
implementation.
Soil is a complex system and is the resultant
product of geology, topography and vegetation cover.
These factors influence the spectral behaviour. Thus,
spectral characteristics and topographic information are
the possible clue for differentiating different soils.
The mapping of soil is based on landscape soil
model. The area is subdivided into various physio
graphic soil units based on multiphase stratification.
Each unit is sampled in the field to determine the soil
type. The job of stratification can be carried out using
either visual or digital image analysis techniques. A
number of case studies carried out by various workers
(NBSSLUP 1996 abed; Karale et al., 1991; Kudrat eta/.,
1992), are available which explain the technological
details. A few case studies are being summarized here.
Chamba Block
The Chamba block is a part of Tehri district of
Garhwal Himalayas. The geographical co-ordinates of
the area are 30° 16’ N to 30°26’ N latitudes and 78° 1 1' E
to 78°30’ E longitude. The soil mapping was carried out
using visual interpretation technique at 1:50,000 scale. A
total of 11 soil series associations were observed in this
area. The dominant soils are loamy skeletal/Fragmental
Typic Udorthents, Fine Loamy Typic Eutrochrepts and
Fine loamy Mollic/Typic Hapludalfs (Table 3).
Jainty Watershed
The Jainti watershed is a part of Chhotanagpur
Plateau in Bihar which lies between the latitudes 24°5’
N and 24°15’ N, longitude 86°25’ E and 86°50’ E. The
soil mapping was carried out through digital image
processing at 1:50,000 scale. Five dominant physio
graphic unit viz. Crest, upper pediment, lower pediment,
valley fills and isolated hills are observed in the area.
Detailed physiographic units and soils there in, are
presented in Table 4. Soils are Coarse loamy/loamy
skeletal Typic ustorthents, Coarse loamy Typic
Haplustalfs, Fine loamy Typic Paleustalfs, Fine loamy
Typic Pinthustalfs, and Coarse loamy Aerie Haplaquepts
situated in the crest, upper pediments, lower pediments,
toeslopes, and valley fills respectively.
