Taxonomical Classification of Arable Lands in the District Pulwama of Kashmir , India

Knowledge about morphological, physical and chemical characteristics of soil is an essential requirement for successful crop establishment and output in an area. Taking this concept into cognizance, nine representative soil profiles exposed in the study area were assessed for various properties. Results revealed that the topographical as well as soil morphological features were diverse thereby leading to development of different soil assets. The soils showed varying degree of profile development on foothills (A-C), low hill plateaus (A-Bw-C) and inland valleys (A-Bt-C) horizons, respectively. Particle size analysis revealed that the variation of sand, silt and clay content ranged from 11.7 to 60.6, 22.3 to 60.5 and 17.1 to 35.3 percent, respectively. Organic carbon ranged from 0.02 to 1.72 percent with a mean value of 0.42 percent. Bulk density and particle density ranged from 1.21 to 1.58 Mg m-3 and 2.3 to 2.8 Mgm-3, respectively. The soils were finally recognized to fall under the Entisol, Mollisol and Alfisol orders under taxonomical classification and II, III and IV classes under capability classification with limitations of slope, erosion and wetness. Proper soil managements and diversification of crops can decrease the risk of crop failures caused by such soil limitations.


INTRoDuCTIoN
The significance of a life supporting system in any region lies within the effective land use to give distributional patterns of crops.The rising food prices in the international market, progressive conversion of good lands to grow bio fuel crops, industrial and other non-agricultural uses demand effective soil resource management to ensure productivity, profitability and national food security 1 .For sustainable use of soil resources, a detailed inventory is necessary to strengthen the sustainable development of a region.To achieve soil resource management in agro ecological regions, knowledge on morphological, physical and chemical characteristics and classification is an essential requirement.District Pulwama is a major part of Kashmir valley, India with respect to agricultural perspective 2 and pertinent information about the arable soils is unavailable 3 and hence the present investigation was carried out.

mATeRIALs AND meThoDs
District Pulwama falls between 33 o 46' N to 33 o 52' N latitude and 74 o 45' to 75 o 35' longitude with a mean elevation of 1630 m amsl.The entire area is characterized by sub-humid temperate climate with a mean annual temperature of 14 o C. The moisture and temperature regimes of the area are Udic and mesic, respectively.The natural vegetation of the area consists of trees like Salix spp., Populous spp., Planetarium orientalis, Roubinea spp.etc.The hill ranges are covered with forests and dominant species are Pinus sylvestris, Pinus walichiana, Cedrus deodara, Abies pindrow and Picea smitheana.The district is rich in horticulture and agriculture 4 and the main crops include paddy, fodder, saffron (Croccus sativus), apple (Malus spp.) and condiments.
After a general traversing of the study area nine representative profiles were selected for study (Fig- 1).Landforms were delineated on the basis of image interpretation of Resourcesat-1 LISS-III data and ground truth study i.e. geology, drainage pattern, surface features, slope characteristics and present land use (Fig- 2).The reconnaissance survey was carried out in 1:50,000 scale using Survey of India toposheet as a base map of the same scale.The soil site description was made following the standard proforma of soil site description of NBSS&LUP soil bulletin no.23 5 .The detailed morphological description of these nine profiles was studied in the fields as per the guidelines in Field guide for Soil Survey 6 .The soil samples collected from different horizons were air dried and grounded in a wooden pestle and mortar.Ambient soil was passed through 2 mm sieve and then subjected to various physical and chemical analysis.The particle size analysis was carried out by international pipette method 7 using sodium-hexametaphosphate as a dispersing agent.The textural class was determined using the USDA textural triangle.Soil reaction (1:2.5 soil and water suspension) was determined by ph meter 8 and electrical conductivity (EC) of soil water extract was determined with the help of conductivity bridge 9 .Organic carbon (OC) was determined by chromic acid wet digestion method 10 .Estimation of calcium carbonate was done by rapid titration method 7 .Cation exchange capacity (CEC) was determined by Schollenberger and Simon (1945)  11 method of leaching the soil with neutral normal ammonium acetate.The exchangeable cations were extracted with neutral normal ammonium acetate.Potassium (K) and sodium (Na) were determined by flame photometer while, calcium (Ca) and magnesium (Mg) were determined by atomic absorption spectrophotometer procedure 12 .Bulk density (BD) and particle density (PD) were determined by Core sampler 13 and Pycnometer method 14 ,respectively.The soils were classified taxonomically up to sub-group level following Keys to Soil Taxonomy 15 .Moreover, considering limitations and potentials of the soils, Land Capability Classification was evaluated as per guidelines outlined by Klingebiel and Montgomery (1961) 16 .

soil morphology
The solum (A+B horizon) was moderately deep to deep in all the profiles except P 4 which was shallow (Table -2).The colour hue was 10YR in all the profiles with a value of 2 to 5 and chroma from 1 to 4. In general, all the soils were characterized by brown colour mixed with shades of grey and yellow.The soil colour appears to be the function of chemical and mineralogical composition as well as the textural makeup of the soils and conditioned by topographic position and moisture regime 17 .The various shades like dark brown, very dark brown, yellow brown colour in surface and sub-surface horizons of profiles indicate a good drainage condition of the soils 18 .The structure of the surface soils varied from fine weak granular to medium moderate crumb which can be attributed to continuous soil manipulation and continuous addition of organic matter 19 .The subsurface horizons showed a definite structure of subangular to angular blocky which may be attributed to the increase in clay fraction and compaction 20 .
The consistence of the soils varied from slightly hard to hard (dry), friable to very firm (moist) and slightly sticky to sticky (wet).The increase in hardness, firmness and stickiness with depth is due to increase in compaction and clay content in sub-surface horizons 1 .Slight to strong effervescence was observed in all profiles especially in sub-surface horizons except P 2 P 6 , P 8 and P 9 which showed no effervescence.The horizon boundaries are clear to gradual in distinctness and smooth to broken in topography.

soil Characteristics Physical characteristics
The detailed physical characteristics of the soils are presented in table-3.Perusal of the data reveals that the sand, silt and clay content are in the range of 11.7 % to 60.6 %, 22.3 % to 60.5 % and 17.1 % to 35.3 % with mean value of 32.14 %, 42.01 % and 25.84 %, respectively.All profiles showed a decrease in sand fraction down the depth except P 3 and P 6 which showed an increasing trend that can be attributed to the in situ weathering of the parent material.The silt fraction showed a decrease with depth in all the profiles except P 3 with an increase in silt fraction down the depth which may be due to the less weathering intensity and alluvial depositions of the parent material 21 .Clay exhibit a decrease down the depth in P 4 which may be attributed to the less intense weathering due to low rainfall, severe erosion and sparse vegetation 18 .The bulk density and particle density ranged from 1.21 to 1.58 Mgm -3 and 2.3 to 2.8 Mgm -3 , respectively with a regular increasing trend with the depth.The increase in bulk density may be attributed to the increase in organic matter and more compaction of finer particles in deeper layers caused by over-head weight of surface soil 17 .The increase in particle density could be attributed to increase in total sand fraction in sub-surface horizon 22 .

Chemical Characteristics
In general, the soils were neutral to slightly alkaline in reaction with the ph variation from 6.49 to 8.42 (Table 4).The ph showed a regular increase with the depth in all the profiles which can be attributed to decrease in organic matter, leaching of bases and accumulation of calcium carbonate at sub-surface horizons of the profiles 23 .EC of the soils showed non-saline nature and ranged between 0.01 to 0.19 dSm -1 with a regular increase with the depth in all the profiles, attributed to the leaching of soluble salts 19 .
The organic carbon content of these soils showed a conspicuous variation within the profile which was higher in surface than in the sub-surface horizons.It ranged from 0.02 to 1.72 percent with a mean value of 0.42 percent.The higher values in surface horizons may be due to the continuous organic manuring, addition through vegetation and low mineralization rates in these soils 19 .
The exchangeable calcium was dominant cation in all the soil profiles followed by magnesium, potassium and sodium with their values ranging from 3.87 to 4.61 cmol (p + ) kg -1 , 0.40 to 0.47 cmol (p + ) kg -1 , 0.10 to 0.29 cmol (p + ) kg -1 and 0.07 to 0.42 cmol (p + ) kg -1 , respectively.The content of these exchangeable cations showed irregular trends with soil depth which can be attributed to the root distribution of principal crops and prevalence of weathering of clay minerals 24 .The calcium carbonate content was present in meagre amounts in most of the profiles while as P 3 and P 4 had considerable amount of calcium carbonate (Table-4).
Cation Exchange capacity of the soils showed little variation between and within the profiles.Profiles P 1 , P 5 and P 9 showed an increasing trend, P 2 , P 3 , P 6 , P 7 and P 8 showed irregular patterns while as P 4 showed a decreasing trend of CEC with the depth.The different distributional patterns of CEC very sticky so : non-plastic sp : slightly plastic mp : moderately plastic p : plastic within the depths may be attributed to the presence of organic matter 19 and illuviated clay 25 .

soil Classification
On the basis of morphological and physicochemical characteristics, the soils of the study area were classified into taxonomical units as per Keys to Soil Taxonomy 15 into three major orders i.e.Alfisol, Mollisol and Entisol.Profile P 1 was classified as Alfisol while P 2 , P 3, P 6, P 8 and P 9 as Mollisols and the profiles P 4 , P 5 and P 7 were classified under Entisol order.The soils were classified up to sub-group level (Table -5).
The soil of Shikargah (P 1 ) was classified under the order Alfisol due to the presence of ochric epipedon and kandic endopedon and was further sub grouped as Typic Kandiudalf.The soil profiles of Pinglish (P 2 ), Chersoo (P 3 ) and Pinglena (P 9 ) showed mollic epipedon and argillic endopedon in each and were classified under order Mollisol.The profile P 2 and P 9 were found to be saturated with water for 20 or more consecutive days in a year and were classified under Oxyaquic Argiudolls at sub-group level.
Profile P 3 showed aquic conditions throughout the year with redoximorphic features in sub-surface horizon and was thus sub-grouped under Aquic Argiudoll.The soil profiles of Chandhara (P5) and Kamrazipora (P7) showed ochric epipedon and no distinct endopedon and were classified under Entisol order.Profile P 5 was classified under Typic Udorthents sub-group due to non-fluvial nature of soils while as profile P 7 showed distinct fluvial nature and hence classified under Typic Udifluvents at sub-group level.The soil profile of Ladhoo (P 6 ) and Uthmula (P 8 ) showed the presence of only mollic epipedon characteristics with a base saturation of >35 percent throughout the profile and were categorized as Mollisols.These profiles were keyed out as Typic hapludolls at sub-group level.Profile Barsu (P 4 ) showed neither an epipedon nor any endopedon, hence qualified for Entisol order.Due to the presence of rock fragments in profile and sandy loam texture throughout the depth and presence of lithic contact, hence the profile was classified under Lithic Udipsamments sub-group.

Land capability classification
Land Capability Classes, on the basis of criteria 16 , were framed as per according to site features studied in the field, morphological and physico-chemical characteristics.Three capability classes II, III and IV were found to be prevalent in the study area (Table-6).
The land capability sub-classes indicate that the soils are moderately well to fairly good cultivable and physical conditions in order to maximize the productivity and profitability out of the soils to enhance better economy of the area.
In conclusion, the varying degree of profile development reflects the different degree of weathering intensity.Soils are having neutral to slightly alkaline reaction.Electrical conductivity is under normal range.Profiles show clay illuviation but the low values of CEC depicts low active clays.The presence of higher organic matter in surface

Table 6 : Land capability classification of arable soils of district Pulwama
profiles reflects good physicochemical properties.The land capabilty classes viz: II, III and IV in the study area reveals that the soils are cultivable but hold some limitations for use and hence an alternate option was provided.