Morphology, physico-chemical properties and classification of some vertisols of Jabalpur

Three Vertisol pedons in Jabalpur district, were morphologically studied, characterized and classified. The soils are very deep, colour ranges from dark brown (10YR3/1) to very dark grey (10YR4/3) in different horizons. The texture of deep soils clay of all pedons throughout the profile. Crack of 2-3 cm wide extends beyond one meter. Slickensides, wedge shaped aggreagates, Fe, Mn and calcrets are observed in all the soils pedons. The soil are imperfectly drained. The soils are calcareous and PH ranged form neutral to mildy alkaline. The organic carbon content in these soils were low to medium in surface and that too decreased with depth. Effervescence was observed in all the soils pedons in lower horizons. The soils are base rich and high in CEC : clay ratio (0.60 to 0.93) and are classifed as Typic Haplusterts.


INTRODUCTION
In Madhya Pradesh, Vertisols occupy 16.7 m ha (Tomar et al. 1995) mainly in the district of Jabalpur, Narsingpur, Hsoangabad, Sagar, Indore, Khandwa, Khargone, Dhar, Dewas, Shajapur, Bhopal etc.The dominant soil constraints are unfavorable tilth, wide and deep shrinkage cracks, slow saturated hydraulic conductivity in sub soil and prone to erosion in the uplands.However, and adequate information or characteristics of these is rather limited in Madhya Pradesh and hence present investigation was carried out.

MATERIAL AND METHODS
The study was carried out at Department of Soil Science and Agricultural Chemistry, Jawaharlal Nehru University Jabalpur.Three pedons were morphologically described (Soil Survey Division Staff, 1995).Horizon wise soils samples were collected, dried and processed.The samples were analysed for particle size distribution by Bouyoucos hydrometer methods, bulk density by tapping method (Johnson, 1979) and pH and electrical conductivity in 1: 2.5 soil water suspension (Piper, 1966).Calcium carbonate was estimated by rapid titration method (Piper, 1966).Cation exchange capacity and exchangeable cations were determined as described by Bower et al. (1952) and Black (1965), respectively.Based on morphological, physical and chemical properties, the soils were classified as per key to Soil Taxonomy (Soil Survey Staff, 1998).

Morphological features of the soils
Salient morphological characteristics of the pedons are presented in table 1.The colour of the soil in hue 10YR, value ranged form 2 to 4 chroma 1 to 2 and the low chroma indicates poor drainage of the soils.The dark colour in these soils may be partly due to high content of ilmenite along with fine sub angular blocky sly due to high content of ilmenite along with fine sub angular blocky sly due to high content of ilmenite along with other dark coloured ferromagnesian minerals (Sahu et al. 1982).Granular to weak fine sub angular blocky structure was noticed in surface horizons of all the pedons, While strong medium angular blocky to strong coarse angular blocky structure in sub soil horizons of pedons 1 and 3.The structure in sub soil horizons of pedon 2 was moderate medium sub angular blocky throughout the profile.Cracks of 1 to 3 cm wide gilgai micro-relief are normal surface features in the area.These soils have intersecting slicken sides and shiny pressure faces in sub surface horizon indicating shrink swell properties of the soils.Presences of Fe-Mn concretions in all the sub surface horizons is attributed to slow to very slow permeability and reduction-oxidation cycle.Few and fine to foarse iggegular calcrets are observed in the lower horizons of all the pedons.

Physical and chemical properties
The data on particle size distribution (Table -2) indicate that the soils were clayey

Classification of the soils
Based on morphological and physicochemical properties the soil of the study area have been classified as per the criteria given in the keys to Soil Taxonomy (soil Survery Staff, 1998).The presence of a layer more than 25 cm thick associated with slickendsides close enough to intersect in sub horizons, more than 30 percent clay in the fine earth fraction and 1-3 cm wide cracks up to 1 meter quality for Vertisols (P 1 , P 2 and P 3 ) and Typic Haplusterts as sub group level.

Table - 2: Physical properties of soils Pedon 1 Very fine, Smectitic, hyperthermic, Typic halpusters
The exchange complex is mostly saturated with Ca ++ followed by Mg ++ , Na+ and K + .The exchangeable Mg ++ and Na + increased and Ca ++ remained almost constant with depth.It is assumed that Na and Mg salts are relatively more soluble than the Ca salts and leached down to lower layers.