SOIL
PREAMBLE:
Soil systems have developed over many millions of years and they can be
influenced by numerous factors. Some of these factors involve natural influences and
others are related to man-induced influences. The primary point is that the soil
characteristics in a given geographical area at a given point in time are a function of both
natural influences and human activities. The geological features in an area are also a
function of natural forces and processes, which have existed or occurred over million of
years. The soil and geological environments are typically associated with the physical
and chemical environment. However, they also exhibit fundamental relationships to
other environmental components.
IDENTIFICATION OF SOIL IMPACTS:
Soil Quantity – Quality:
An appropriate initial activity when analyzing a proposed activity is to consider
what types of soil or geological disturbances might be associated with construction and
operational phases and what quantities of potential soil contaminants are expected to
occur. There are no generic methodologies to identify the potential impacts on soil and
geological environments. Regarding the identification of potential soil pollutants, a list
of the materials to be utilized during the project and those materials, which will require
disposal, could be developed. Examples of materials that may result in soil
contamination include oil and fuel, insecticides, fertilizers, chemicals, solid and liquid
waste.
Soil Characteristics:
Many impact studies have been characterized by thorough presentations of
information on existing geological information in the project area on pertinent soil
information. The key principle in describing the affected soil and geological
environment is to consider potential impacts, and then to address the relevant soil and
geological features that might be changed by the proposed project or some influence on
project design. Some soil surveys could be used, because of the relatively slow change of
soil characteristics over time. It may be desirable to organize the soil information
according to topographical features of the area. A particularly important source of
information for addressing surface soils and associated land uses may be aerial
photographs. Several information- storage and retrieval systems have been developed
which incorporate soil and geological data.
Based on the survey conducted by State Soil Survey Organization nineteen series of soil
were identified in Pondicherry region and the identification is based on their land
capability, irritability, texture and productive potential.
Capability is an interpretative classification made for agricultural use according to their
potentialities and limitations for sustained protection. There are four kinds of limitations
at the sub class level namely,
E – erosion
W – wetness or overflow
S – soil limitations affecting the plant growth
C – limitations due to climate
Irrigability – classification is made on the basis of soil characteristics, textures, depth,
and available moisture holding capacity, permeability and saline sodic conditions.
Texture – In general eight texture of soil are found in Pondicherry region viz., sand, clay,
sandy loam, clay loam, sandy clay, silty clay, loamy sand, sandy clay loam.
GEOLOGY
In Pondicherry region the entire area, except the northeastern corner is mostly covered by
sedimentary formations ranging in the age from cretaceous to recent. The general
description of the various geological formations encountered in this region is given below
:
GEOLOGICAL TABLE :
Era Period Formations Lithology
Quaternary Recent Alluvium Sands, clays, silts, cankar
Laterite Gravels, laterite
Miopliocene Cuddalore Pebbly and gravelly and coarse-grained
sand stones with minor clays and silt –
stones with their sleams of lignite.
Tertiary Paleo-Cene Manaveli Yellow and yellowish brown.
Slit stone and clay stone with their bands
of limestone.
Kadaperi Yellowish to dirty white sandy,
limestone calcarcous sand stone and
clays.
Mesozoic Upper Ottaiclay Greyish to grayish green clay stones,
Cretaceous silts with this bands of sandy lime stone
and fine grained calcareous sandstone
Vanur Sand cluartzite, sandstones, hard coarse
grained, occasionally feldspathic or
calcareous with minor clays.
Lower
Ramanthapuram Black carbonaceous silty clay and fine to
Cretaceous
medium grained sands with bands of
lignite and medium to coarse-grained
sandstones.
Era Period Formations Lithology
Quaternary Recent Alluvium Sands, clays, silts, cankar
Laterite Gravels, laterite
Miopliocene Cuddalore Pebbly and gravelly and coarse-grained
sand stones with minor clays and silt –
stones with their sleams of lignite.
Tertiary Paleo-Cene Manaveli Yellow and yellowish brown.
Slit stone and clay stone with their bands
of limestone.
Kadaperi Yellowish to dirty white sandy,
limestone calcarcous sand stone and
clays.
Mesozoic Upper Ottaiclay Greyish to grayish green clay stones,
Cretaceous silts with this bands of sandy lime stone
and fine grained calcareous sandstone
Vanur Sand cluartzite, sandstones, hard coarse
grained, occasionally feldspathic or
calcareous with minor clays.
Lower
Ramanthapuram Black carbonaceous silty clay and fine to
Cretaceous
medium grained sands with bands of
lignite and medium to coarse-grained
sandstones.
Soil Site:
Soil site is selected by different location in the Pondicherry region. In this study we have
chosen four different location site such as site I in Ariyur site II inVadamangalam site III
in Tiruvandarkoil and site IV in Uruvaiyar.
OBSERVATION TABLE
Sl. Observation
Parameter
No Site I Site II Site III Site IV
1 pH 7.9 7.2 7.5 7.1
2 Electrical Conductivity(E.C) 0.24 0.32 0.27 0.38
3 Calcium(Lime Status) N* N N N
4 Soil Texture Loamy Clay Loamy Silty clay Clayish loam
sand
5 Nitrogen (Kg/A) 78 85 62 55
6 Phosphorus (Kg/A) 8.6 9.2 7.9 8.8
7 Potassium (Kg/A) 39.3 41.7 43.6 38.5
Note : * Not Traceable
Observation at the Project Site
Observation
Sl.
Parameter Sample
No Sample I Sample III Sample IV
II
1 pH 7.8 7.5 7.7 7.2
2 Electrical Conductivity(E.C) 0.31 0.28 0.27 0.22
3 Calcium(Lime Status) Feeble Feeble Feeble Feeble
4 Soil Texture Loam Loam Loam Loam
5 Nitrogen (Kg/A) 64 70.5 69 73
6 Phosphorus (Kg/A) 7.8 8.2 8.4 7.9
7 Potassium (Kg/A) 35.5 38.1 33.4 32.3
ASSESSMENT OF IMPACT SIGNIFICANCE:
Several approaches can serve as a basis for interpreting the anticipated project induced
changes to the soil environment. One is to consider the percentage and direction of
change from existing conditions for a particular soil environmental factor. Second is to
apply the provisions of pertinent federal, state laws and regulations to silo environment.
Third approach for interpreting anticipated changes relies upon professional judgment
and knowledge. Another approach to impact assessment is to consider the anticipated
changes in relation to look-alikes or the application of information from relevant case
studies.
This chapter addresses a variety of considerations associated with predicting and
assessing a proposed projects potential impacts on the soil environment. The above
methodological framework represents a logical approach, which begins with the
identification of potential impacts and associated with environmental setting information
and impact prediction and significance. Impact interpretation is to be based upon
technical assessment and the suitable application of relevant institutional information.
Impact-mitigation measures also identified and incorporated to minimize undesirable
effects.
Soil quality results reveals that the lands are more fertile in nature and the major crops are
paddy, sugar cane and coconut. The minor crops are groundnut, casuarinas and tapioca.
The major cropping pattern are more water intensive and the cropping pattern is given in
the following table.
S.No Village Paddy Sugarcane G.Nut Tapioca Casuarina Plantain Coconut
1 Pangur 238 24.7 2.1 6.45 2.4 1.85 7.5
2 Mangalam 185 6.9 4.35 1.33 0.23 2.22 5.08
3 Uruvaiyar 224 3.4 1.65 0.98 0.10 1.03 3.45
4 Thirukkanchi 98 1.2 0.68 2.11 1.2 0.56 4.21