SOIL
SURVEY & TESTING
SOILS OF NAGALAND: -
For any land based development
planning, it is necessary to classify soil resources scientifically by a systematic
survey. In fact Soil Survey is the starting point for all the Soil Research and long term
Land Use Planning. The Soil Survey Wing of Soil and Water Conservation, Nagaland thus
conduct soil survey and land-use planning and classify the soils that can be grouped,
sub-divided and regrouped to permit the largest number and the most precise predictions
possible about responses to management and manipulation.
To
classify soils into uniform families systematically with uniform nomenclature so that they
can be correlated with those in other areas, regions and countries Soil survey adopt the
Internationally Common Soil Survey Manual of United States Department of Agriculture. For
this purposes soil sample testing results, field studies and observation of soil inherent
characteristics can evolves the nomenclature of the soil family and is done only by the
experience trained personnel.
The
soils of Nagaland belongs to 4 orders, 7 sub-orders, 10 great groups, 14 sub groups and 72
soil families. The 4 orders found in Nagaland are (i) Alfisols (ii) Entisols (iii)
Inceptisols and (iv) Ultisols. Inceptisols dominate the soils of the State with 66%
followed by Ultisols 23.8%, Entisols 7.3% and Alfisols 2.9% of the total 16.6 million Ha.
of the State Geographical Area.(Soil Map enclosed)
(i)
ALFISOLS :
Alfisols are
base-rich mineral soils of sub-humid and humid region. They have light coloured surface
horizon over a clay enriched sub –surface horizon that is rich in exchangeable cations with base saturation of more than 35%. This
type of soil order is found on the western flank of the State bordering Assam. They are
deep and well drained of fine to fine loamy texture. Common families of Alfisols which
have been identified in Nagaland are :
(1)
Fine typic Kanhapludalfs
(2)
Fine loamy typic Paleudalfs
(ii) ENTISOLS :
They are recently
developed, mineral soils with no diagnostic horizon. This is because either of limiting
time available for development or because of exceedingly unfavourable conditions. This
soil order is found on the Western and North Western part of the State on the low hill
slope and narrow river valleys. They are moderately to deep, well drained, fine to fine
loamy textured soils. Families which have been identified under this orders are :-
(1) Fine-loamy typic Udifluvents
(2) Fine-loamy typic Udorthents
(3) Coarse-loamy typic Udorthents
(4) Fine-loamy Lithic Udorthents
(5) Coarse loamy Lithic Udorthents
(iii) INCEPTISOLS :
This soil order represents beginning stage of
soil formation which is belong to that of Entisols but still short of the degree of
development found in Alfisols. They may have some accumulation of clay in the sub-surface
horizon, limiting in depth, organic matter content, and base saturation. This soil
dominates the entire State having fine loamy, fine clay, clay loam etc. soil textures with
moderately shallow to deep soils with moderately to excessively drained. The identified
families under this order are:
(1) Fine- loamy Umbric Dystrochrepts
(2) Fine loamy typic Dystrochrepts
(3) Fine Umbric Dystrochrepts
(4) Loamy , skeletal Umbric Dystrochrepts
(5) Fine typic
Dystrochrepts
(6) Loamy-skeletal typic Dystrochrepts
(7) Clayey-skeletal Umbric Dystrochrepts
(8) Loamy-skeletal Pachic Haplumbrepts
(9) Fine Pachic Haplumbrepts
(10)
Fine-loamy typic Haplumbrepts
(11)
Clayey-skeletal Pachic Haplumbrepts
(12)
Fine loamy Pachic Haplumbrepts
(13)
Fine-loamy Dystric Eutrochrepts
(14)
Coarse loamy typic Dystrocrepts
(15)
Loamy skeletal typic Dystrocrepts
(16)
Loamy skeletal Dystric Eutrocrepts
(iv) ULTISOLS :
The Ultisols are
similar with Alfisols, except for having low base saturation on the exchange complex due
to advance stage at weathering. These are base-poor mineral soils of humid region
developed under high rainfall and forest vegetation. They are characterized by low, less than 35% base saturation and clay enriched
sub-surface horizon. This soil is sparely scattered in all parts of the State having fine
loam, clay loam and clayey texture. Well to excessively drained with moderate to deep
soils. The families under this order which have been identified so far are :
(1) Fine Humic
Hapludults
(2) Fine Typic
Paleudults
(3) Fine Typic
Haplohumults
(4) Fine loamy typic
Hapludults
(5) Fine typic
Hapludults
SOIL TESTING
:
The Soil
Testing Laboratory in the Department has an infrastructure to analyse 10,000 soil samples
annually. Physical and chemical analysis are the two methods commonly used to determine
the inherent physical and chemical properties of soil. Chemical analysis is done to
determine fertility status of soils and physical analysis for determining the soil
textures. The Department has already completed Soil Test
and fertility status report in 5(five) districts viz. Kohima, Wokha,
Mokokchung, Mon & Tuensang and reports and maps have already published. The Soil
Testing Laboratory in the Department is also equipped with the modern equipments for
determining micro nutrients.
Soil testing
analysis of both physio-chemical procedures help in grouping of soils into classes by the
level of nutrients, soil texture and other soil conditions. With this it is possible to
classify families of the soils and prepare the soil maps, fertility maps etc. of a
particular area.
Sampling procedure for fertility status : Composite samples are collected from small portion of soil
at the depth of 0-15cm by means of suitable sampling tools from atleast 10-15 well
distributed spots after scrapping off the surface litter.
The soils collected
in this manner is thoroughly mixed. The bulk is reduced by quartering process to about 500
grams and pack in polythene bag. The soil is
dried in the room temperature and packed in cloth or polythene bags with description and
identification marks. Then it is dispatch to the soil testing laboratory for analysis such
as pH, Nitrogen, Phosphorous, Potassium content and micro elements like copper,
iron, manganese, iodine, organic carbon etc. and the results of the analysis is back to
the farmers and agents.
Sampling of soil profile : The soil
profile is the vertical section of the soil where soil horizons are demarcated by
observing the colour, texture, consistency roots etc. to an extent of parent material or
150cm, whichever is earlier. After observing and noting all the characteristics, soil
samples are collected from each and every horizons starting from the bottom to avoid
contamination. The soils are packed in cloth or polythene bags and labeled with the
profile No. depth and other identifications and sent for analysis in the soil testing
laboratory. The soil samples are then air dried in the shade room temperature. The soils
are ready for physio-chemical analysis.
The results of the
laboratory analysis are then used for correlation of different soil families, preparation
of soil maps and reports of particular project or area.
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