1. Distribution and characterization of soil organic carbon under different ecosystems of Red and Laterite zone of West Bengal 
P. K. Patra, Sajal Saha*, Dipsikha Chakraborty and S. K. Ghosh
Department of Agricultural Chemistry and Soil Science, B.C.K.V., Mohanpur, Nadia, West Bengal *
INTRODUCTION
MATERIALS AND METHODS
Soil organic carbon (SOC) being an important index of soil quality playing a crucial role in sustaining crop productivity and environmental quality, its augmentation and conservation at equilibrium level is a frontal challenge of resource management for the purpose of maintaining productivity of soils .
The total SOC per se may not be so important but its different pools differing in their susceptibility to oxidative forces, act as sensitive indicators of the impact of management practices that are important for crop productivity and maintain soil quality.
 To make the programme for restoration of soil quality through soil organic carbon (SOC) management successful, comprehensive knowledge on SOC stocks forms an essential prerequisite.
The present work was undertaken to characterize different fractions of organic carbon distributed in three soil depths viz., 0-15, and cm, under six ecosystems of six soil series collected from Red and Laterite Zone of West Bengal.
Triplicate soil samples collected from each site were analyzed for their physico-chemical properties viz., pH and CEC; particle size analysis for determining textural class; total carbon content, organic carbon content and different fractions of soil organic carbon (SOC) on the basis of their oxidisability following standard methods.
All variables were statistically analysed following methods meant for Incomplete Factorial Completely Randomised Design (CRD)
DETAILS OF INITIAL SOIL
Series
Location
GPS location
Elevation
Land Use Pattern
Classification
Typifying pedon
Jhargram
Vill- Jhargram
P.S- Jhargram
Dist-Medinipur
22°27´N lat.
87°00´E long.
174 ft
Rice up land (L1)
Rice medium land (L2)
Rice low land (L3)
Fallow land (L4)
Eucalyptus forest (L5)
Mango orchard land (L6)
Fine-loamy, mixed, Hyperthermic, Ultic Paleustalfs
Fine loam
Saripabasa
Vill-Saripabasa
P.S- Belpahari
22°38´N lat.
86°44´E long.
445 ft
Sal forest (L5)
Cashew orchard land (L6)
Loamy mixed, huperthermic, Lithic Ustochrepts
Clay loam
Dhanchia
Vill- Dhanchia
P.S- Goaltor
22°44´N lat.
87°15´E long.
181 ft
Fine-loamy, mixed, hyperthermic, Ultic Paleustalfs
Sandy loam
Kushmasuli
Vill- Kushmasuli
22°43´N lat.
87°17´E long.
203 ft
Fine-loamy, mixed, hyperthermic, Rhodic Paleustalfs
Barakadra
Vill- Barakadra
22°42´N lat.
87°13´E long.
211 ft
Fine, mixed, hyperthermic, Aquic Haplustalfs
Loam
Ruisanda
Vill- Ruisanda
P.S- Kharagpur
22°22´N lat.
87°21´E long.
221 ft
Fine-loamy, mixed, hyperthermic, Vertic Endoasqualfs
OBJECTIVES
To study the present status of different fractions of soil organic carbon at different depths (0-15 cm., cm. and cm.) of six soil series under six ecological situations from one of the less productive agro-climatic zone i.e. the red and laterite zone of West Bengal.
To study the relationships among different forms of carbon with some relevant physico-chemical characteristics of the soil. 
RESULTS
All the studied parameters of the six soil series under different ecosystems differed significantly (F< 0.05)
Soil Series (S) pH EC
(dS m-1) OC
(%)
T_C
Pool_1
Pool_2
Pool_3
Pool_4
Active_
Pool
Passsive
_Pool
Lability
_Ind
Available
l_N
(kg ha-1)
Jhargram (S1)
5.99cd
0.07c
0.396d
1.642f
0.230c
0.099d
0.067c
1.246a
0.329d
1.313f
0.591c
175.5b
Saripbasa (S2)
6.07b
0.471b
1.848c
0.250b
0.111c
0.110b
1.377c
0.361b
1.487d
0.600b
173.6d
Dhamcha (S3)
6.04bc
0.09a
0.323e
1.764e
0.145e
0.068e
1.441b
0.214e
1.551c
0.390f
172.1a
Kushmasali (S4)
5.94d
0.09ab
0.514a
1.811d
0.267a
0.126a
0.121a
1.297d
0.393a
1.419e
0.654a
173.8cd
Barakadra (S5)
6.01c
0.445c
1.893b
0.212d
0.116b
0.117ab
1.448b
0.328d
1.565b
0.515e
174.0c
Ruisanda (S6)
6.43a
0.08b
0.477b
1.939a
0.231c
0.120b
1.462a
0.351c
1.588a
0.549d
177.8a
F Test
***
Ecosystems (ES)
Rice Upland (ES1)
6.29a
0.08a
0.448c
1.801d
0.226c
0.123a
0.100d
1.353b
0.349b
1.453c
0.573b
185.6a
Rice Medium Land (ES2)
6.28a
0.08ab
0.464b
1.921b
0.246b
0.109c
0.109bc
1.458a
0.355a
1.567ab
0.559c
181.8b
Rice Low Land (ES3)
6.25a
0.479a
1.936a
0.243b
1.457a
0.359a
1.577a
0.564c
178.1c
Fallow (ES4)
5.48d
0.325e
1.570f
0.156e
0.081f
0.088e
1.245c
0.237d
1.333d
0.458e
153.9f
Forest (ES5)
5.69c
0.459b
1.680e
0.254a
0.105cd
1.221d
0.354a
1.325d
0.661a
170.2d
Orchard (ES6)
6.16b
0.411d
1.859c
0.202d
0.093e
0.115ab
1.448a
0.296c
1.563b
0.493d
168.0e NS
Depth of Sampling (D)
0-15 cm (D1)
6.03a
0.454a
1.895a
0.234a
0.108a
0.113a
1.441a
0.341a
1.554a
0.555a
187.0
15-30 cm (D2)
6.06a
0.432b
1.828b
0.222b
0.106b
0.103b
1.396b
0.329b
1.499b
0.542b
174.3
30-45 cm (D3)
6.07a
0.418c
1.687c
0.213c
0.103c
0.101c
1.269c
0.316c
1.371c
0.563c
161.7
METHODS ADOPTED
Parameters
Methods pH
Jackson(1967)
Soil Texture (Mechanical Analysis)
Bouyoucos, 1962
CEC
Schollenberger and Simon ,1945
Oxidisable Organic Carbon
Walkley and Black ,1973
Available Nitrogen
Subbiah and Asija,1956
DISCUSSION
Among six soil series
Clay content ranged from 6.1% to 44.3%
Soils were acidic with pH values ranging from 5.94 to 6.43
Low CEC [c mol (p+) kg-1 soil] ranging from 4.10 to 23.59
Organic carbon content (%) of all the soils ranging from to were below the minimum threshold limit of 0.63%
Pool_1 SOC (%) ranged from to 0.267
Pool_2 SOC (%) ranged from to 0.126
Pool_3 SOC (%) ranged from to 0.126
Pool_4 SOC (%) ranged from to 1.462
Total carbon content (%) ranged from to 1.939
Among six ecosystems
Clay content ranged from 7.95% to 11.16%
pH values ranged from 5.48 to 6.29 , i.e acidic
CEC [c mol (p+) kg-1 soil] ranged from 7.95 to 11.16
Organic carbon content (%) ranged from to 0.479
Pool_1 SOC (%) ranged from to 0.254
Pool_2 SOC (%) ranged from to 0.123
Pool_3 SOC (%) ranged from to 0.121
Pool_4 SOC (%) ranged from to 1.458
Total carbon content (%) ranged from to 1.936
CONCLUSION
Severe soil erosion owing to the undulating topography of this region resulted in such lower values of different fractions of organic carbon in this eco-region.
Low clay content of the soils also led to less stabilization of carbon and low or no application of organic manures also have contributed to such low values.
Integrated application of organic manures/crop residues along with balanced application of chemical fertilisers and low cost liming materials becomes utmost necessity in these soils.
Proper management of soil health may also call for selecting appropriate cropping pattern including both cereals and legumes in sequence.
The complexity of the nature of soils, also pointed out to the need for making inventory of the different available resources, both natural and social, to develop technology for specific areas for conserving soil carbon and improve soil health.