ERODIBILITY INDICES OF SOILS UNDER DIFFERENT LAND USE SYSTEMS OF JAMMU REGION
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Date
2011
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
An investigation entitled, "Erodibility indices of soils under different land use systems of Jammu region" was undertaken to study different erodibility indices and physico-chemical characteristics of the soils under five different landuse systems viz agriculture, horticulture, forest, grassland and barren lands in three agro climatic zones of Jammu region; subtropical, intermediate and temperate. The study was undertaken with following objectives: (i) to characterize the soils under different land uses on the basis of various physico-chemical properties of soil (ii) to determine the erodibility indices of the soils under different land use systems and (iii) to work out the relationship between soil properties and erodibility indices. For this study, 268 samples based on the recormaissance soil survey from different locations of Jammu region comprising surface (0-22cm) and subsurface layers (22-45cm) were collected and investigated for their physico-chemical properties and erodibility indices. Different erodibility indices viz. clay ratio (CR), modified clay ratio (MCR), Clay/ moisture equivalent (C/Meq), suspension percentage (SP), dispersion ratio (DR), percolation ration (PR), erosion ratio (ER), erosion index (EI) and suspension ratio (SR) were computed and compared. Considering 15, 10, 2.8 a threshold limit of DR, ER and EI between erodible and non-erodible soils, the soils under all the land uses were observed to be erodible in nature. On the basis of susceptibility to erodibility, the landuse systems could be arranged in the order of their erodibility status as: barren lands > cultivated systems (agriculture and horticulture) > grasslands > forest lands. The available macronutrients (N, P and K), organic carbon and C:N were significantly but negatively correlated with DR, ER, EI, SR, PR, CR, MCR and SP in all climatic zones. The 'r' values generally showed positive and highly significant correlations between sand content, bulk density and particle density with SP, CR, MCR, DR, PR, ER, EI, SR in climatic zones. Clay content, porosity and water holding capacity were significantly and negatively correlated with CR, MCR, DR, ER, EI, SR in climatic zones and 'r' values were highly significant in temperate zone. Among landuse systems, the clay was higher in natural vegetation (forest and grasslands) while least was observed in soils under barren lands and cultivated landuse systems (agriculture and horticulture) had intermediate values. The sand fraction recorded highest values in barren lands and least under forests. Among the climatic zones, the finer fractions (clay and silt) were found to be highest in temperate zone while lowest in subtropical zone. The sand was highest in subtropical zone followed by temperate and intermediate zone. The highest water holding capacity was observed in temperate zone while lowest in subtropical zone. Among the erodibility indices, generally the erodibility indices SP, DR, PR, ER, EI, and SR were positively and significantly correlated with each other and highly significant and positive relationship was recorded between CR and MCR (r = + 0.990*). However, EI and SR recorded the highest degree of colinearity with each other (r = + 0.999*). The pH values were lowest in temperate zone and EC did not show any definite pattern in its value in the soils of different landuse systems in climatic zones. The organic carbon in different landuse systems was lower in subtropical zone and highest in temperate zone. Among landuse systems, soils under forest recorded highest organic carbon and CEC while least was observed in barren lands. Among climatic zones, the soils under all landuse systems in subtropical evinced lower fertility status as compared to intermediate and temperate zone. Considering the soil physicochemical characteristics, landuse systems and soil erodibility status, the barren lands in Jammu region require attention to check further degradation. Such lands need to be replaced by more effective soil and water resource conserving systems like agro-forestry, agrihorticulture,
silvi-pasture, controlled and rotational grazing and enclosure of degraded sites for natural regeneration. Cultivated landuse systems (agricultural and horticulture) need to be supplied with sufficient quantity of organic matter to improve soil aggregation, moisture retention and their health especially in subtropical zone.
Keywords: erodibility indices, landuse systems, agroclimatic zones
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