CHARACTERIZATION OF THE SOILS, EVALUATION OF LAND QUALITY CONSTRAINTS AND SOIL-SITE SUITABILITY FOR IMPORTANT CROPS OF JAMNAGAR DISTRICT
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Date
2012-07
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jau,junagadh
Abstract
An attempt has been made to study the physical, chemical, fertility status of soils, to evaluate land quality constraints, soil sustainability and soil-site suitability for important crops of the soils of different talukas of Jamnagar district.
The particle density and bulk density of the soils of Jamnagar district were 2.40 Mg m-3 and 1.30 Mg m-3, respectively. The MWHC and Sat. hydraulic conductivity were found 52.16 per cent and 0.140 cm hr-1, respectively. The moisture held at 0.03 MPa (FC) and 1.5 MPa (PWP) were 0.38 m3 m-3 and 0.17 m3 m-3 whereas AWC was 0.21 m3 m-3.
The soils were found sandy loam to clayey in textures, alkaline in reaction (pH2.5 8.18) and calcareous in nature (CaCO3 54.9 g kg-1). The organic carbon and CEC values recorded as 4.97 g kg-1 and 36.5 cmol(p+) kg-1,respectively in the present study.
The results of fertility status of the soils of different talukas of Jamnagar district revealed that the soils were deficient with respect to available N (208.0 kg ha-1), P2O5 (28.3 kg ha-1) and S (12.24 mg ha-1) whereas, high in available K2O (405.8 kg ha-1). Among the DTPA micronutrients, available Fe (10.41 mg ha-1), Mn (18.04 mg ha-1) and Cu (1.32 mg ha-1) were found sufficient, whereas the soils were medium in available Zn (0.87 mg ha-1).
The average nutrient index values of the soils of Jamnagar district were low for available N (1.15) and P2O5 (1.55), medium for available S (1.69) and DTPA extractable available Zn (2.21) and high for available K2O (2.68), DTPA extractable available Fe (2.48), Mn (2.74) and Cu (3.00).
The results further indicated that the dominance of Ca++ (16.8 cmol(p+) kg-1) and Mg++ (14.3 cmol(p+) kg-1) among the exchangeable cations were observed in the soils while, among the water soluble anions, Na+ (5.87 me l-1) and Cl– (5.43 me l-1) were found in higher proportion indicating NaCl as the dominant salt in soil solution. In the present study 16.0, 17.0, 14.5 and 52.6 per cent soil samples were found saline, saline-sodic, sodic and normal, respectively.
Correlation between fertility and salinity/sodicity indices of soils showed that ECe had highly significantly positive relationships with EC2.5 (r = 0. 988**), SAR (r =0. 672**) and ESP (r = 0.484**). Similarly, pHs had highly significant and positive relations with pH2.5 (r = 0.977**), RSC (r=0.222**) and SAR (r=0.234**). There was a highly significantly close correlation between SAR2.5 and ESP (r = 0.487**) and SSP2.5 (r=0.289**. Obviously, the O.C. was significantly correlated with available N (r =0.626**), K2O (r =0.179*) and B.D. (r=0.191**).
All the soil samples were analyzed for EC and pH from saturated and dilute 1:2.5 extract and the following overall regression equations emerged as follows:
ECe’ = 0.8146+3.7139** EC2.5 (r = 0.9967**)
pHs’ = 0.0968+0.9721** pH2.5 (r = 0.9484**)
Based on the observations of the present study, the soils of Kalavad talukas (Vertic Troparthents) placed in sustainable class S2, whereas the soils associated with the Jamjodhpur (Vertic Troparthents), Bhanvad (Lithic Ustorthents), Kalyanpur (Lithic Ustorthents), Dwarka (Typic Usochrepts), Jamnagar (Lithic Ustochrepts), Lalpur (Lithic Ustochrepts), Jam-khambhalia (Lithic Ustorthents) and Jodiya (Lithic Ustochrepts) were placed in sustainable with high inputs class S3. The management practices of the soils of different talukas are also discussed in the text. Comparing different indicators of soil sustainability with criteria and scoring, it is inferred that cumulative rating index (weighting factors) varied from 25 to 30 in the soils of Jamnagar district.
The soil sustainability of different talukas of Jamnagar district was found in order of Kalavad (25) < Jamnagar (26) < Jamjodhpur (27) < Bhanvad (28) = Lalpur (28) = Jodiya (28) < Jamkhambhalia (29) = Dwarka (29) < Kalyanpur (30) indicating the soils of Jamkhambhalia, Dwarka and Kalyanpur talukas have more soil constraints as compared rest of talukas. The major soil constraits identified in different talukas of Jamnagar district were shallow soil depth, poor soil fertility (low O.C.), high pH, salinity and low saturated hydraulic conductivity.
Alternate land use plans for different talukas of Jamnagar district under study have been suggested for their better management. As far as the cultivation of kharif crops are concerned, the soils belongs to Vertic Troparthents of Kalavad taluka are moderately suitable (S2) for cotton cultivation only, whereas, in case of rabi crops the soils belongs to Vertic Troparthents of Jamjodhpur, Lithic Ustorthents of Bhanvad, Vertic Troparthents of Kalavad and Lithic Ustochrepts of Jodiya talukas are moderately suitable (S2) for wheat cultivation, Vertic Troparthents of Kalavad and Lithic Ustochrepts of Jodiya talukas are moderately suitable (S2) for mustard, whereas, Vertic Troparthents of Jamjodhpur, Lithic Ustorthents of Bhanvad as well as Kalyanpur talukas are moderately suitable (S2) for pearl millet cultivation.