486 in Biosciences 7(6): 486-490, 2014 Trends
Trends in Biosciences 7 (6), 2014
Soil Erodibility Estimation for Soil Conservation in Dapoli Region of Maharashtra SACHIN NANDGUDE1, ASHWINI KAMBALE1, SANGITA SHINDE1, DILIP MAHALE4, VIPUL SHINDE2 1
CAET, Dapoli; Dr. B. S. Konkan Krishi Vidyapeeth, Dapoli, Maharashtra, India-415712, College of Agriculture, NAU, Waghai-394 730, Gujarat (INDIA) email :
[email protected] 2
ABSTRACT Soil erosion associated with non-point source pollution is viewed as a process of land degradation in many terrestrial environments. Solutions to non point source solution problem invariably must address the problem of erosion and sediment control. Nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Hilly coastal Konkan region of Maharashtra state is bestowed by world recognized by unique biodiversity but highly vulnerable to erosion. In natural resources conservation studies, soil erosion is highly dependent on degree of erodibility of particular soil along with the other factors. The erodibility is influenced by various soil characteristics mainly soil texture, structure, permeability and organic matter content. In one of the models Soil-Plant-Air-Water model (SPAW) Hydraulic conductivity was obtained from values of sand (%), silt (%), clay (%) and organic matter (%). Permeability code was derived from the information based on hydraulic conductivity of soil. The average values of percentage of sand, silt, clay were 20.59, 35.29 and 35.68 respectively. Textural classes in lateritic soils of these villages are loamy, clay, silty loam, and sandy loam. The permeability ranges between classes of moderate to rapid. Accordingly the soil erodibility of all villages was estimated in the range of 0.16 to 0.40 with mean erodibility of 0.30. It was also observed that erodibility is inversely linked to the organic matter content of the soil. This study is important because eroded soil subsequently becomes sediment, creating the potential for water degradation. Key words: Hydraulic conductivity, Permeability, SPAW model, Soil Erodibility.
climatic factor, soil characteristics, cropping pattern and conservation practices etc. Soil erodibility is susceptibility and vulnerability of soil to get eroded. It is important hydrologic property of soil which helps researchers and planners in study of soil erosion characteristics. The erodibility is influenced by various soil characteristics mainly soil texture, structure, permeability, organic matter content. However in India at majority of locations and Konkan in particular values of all these parameters are not recorded. Konkan region is the coastal part of Maharashtra state located between Sahyadri ranges on east and Arebian Sea on west. Majority of the part here is hilly and very less hydrologic data is available due to inaccessibility to many parts. On these kinds of locations measurements of many parameters are not feasible. So, empirical relations with use of easily available data can solve the problems to great extent. It can help in hydrologic studies, conservation measures and watershed planning. Keeping this in mind erodibility study was undertaken to understand the soil characteristics and its influence on soil erosion in Konkan region.
Study Area: Dapoli is confined between Sahyadri Hills at east and Arabian Sea at west (15º6’N to 20º22’N latitude and 72º39’E to 72º48’E longitude) with an altitude of 250 m above sea MSL. The climate in this region is humid with relative humidity ranging from 55% to as high as 99%. The average annual rainfall is 3525.05 mm and the temp ranges from 7.5°c to 38.5°c.
MATERIALS AND METHODS Soil, water, plant and air are four foundation pillars on which whole civilization sustains and develops. Soil erosion and sediment deposition are primary causes of adverse impacts to surface water quality. Erosion is a natural process that can be accelerated by human activities. In India majority of geographic area is threatened by various types of land degradation such as water and wind erosion, salinity and alkalinity, water logging etc. Soil erosion is phenomenon of detachment, transportation and deposition of soil particles. This natural process is accelerated due to many unmindful human activities like excavation, construction etc. The erosion is majority affected by
Collection of data: Dapoli area was selected for the study. From the study area 15 villages Kherdi, Aasud, Talsure, Pisai, Anjarle, Bourandi, Kadivali, Umbershet, Kangwai, Chikhalgaon, Kolthare, Ladghar, Gimhvane, Devale were selected. Soil data of (%) sand, (%) silt, (%) clay and organic carbon content were collected from District Soil Testing Laboratory, Ratnagiri. Soil Water Characteristics: It is recognized that soil texture is having the dominant effect for soil water characteristics. However, four additional variables (organic matter, density, gravel, salinity) that can have important
NANDGUDE et al., Soil Erodibility Estimation for Soil Conservation in Dapoli Region of Maharashtra
Table 1. Textural Class proposed Textural Class Very fine Fine Medium Coarse Very Coarse
Range Less than 1 mm thickness 1 – 2 mm thickness 2 – 5 mm thickness 5 – 10 mm thickness More than 10 mm thickness
effect were included in the complete estimation method. Models of soil texture, soil water potential and hydraulic conductivity provide estimates sufficiently accurate for many analyses and decision. In one of Models “Soil - PlantAir -Water” (SPAW) (Saxton and Rawls, 2006) hydraulic conductivity (cm/hr) was obtained from values of (%) sand, (%) silt, (%) clay and (%) organic matter.
Table 2. Structure code for different types of soil by NBSS and LUP (1988) Code 1 2 3 4
Structure Very fine granular Fine granular Moderate or Coarse granular Blocky, platy or massive
Size (mm) 10
Estimation of Hydraulic Conductivity: It is the ability of particular soil to transmit the water through it. The Hydraulic Conductivity was determined by using SPAW model from different soil parameters such as (%) sand, (%) silt, (%) clay and (%) organic matter. Also permeability code was derived based on hydraulic conductivity of soil (Smith and Browning, 1946). Determination of Organic Matter: Organic matter has a variable influence on soil and affects both its chemical and physical properties. The effect of organic matter on physical properties relates largely to its abilities to bind soil particles together. So the organic constituents of soil are important because of their influence on aggregate stability. In present study organic carbon data was available. So, organic matter of soil was determined by following equation. Organic matter=organic carbon × 1.724 .......(1)
Table 3. Permeability classes based on Hydraulic conductivity of soil Smith and Browning (1946) Permeability classes Extremely slow Very slow Slow Moderate Rapid Very rapid
Hydraulic conductivity(cm/hr) < 0.0025 0.0025-0.025 0.025-0.25 0.25-2.5 2.5-25.00 > 25
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Table 4. Permeability code for different types of soil Smith and Browning (1946) Code 1 2 3 4 5 6
Description Rapid Moderate to rapid Moderate Slow to moderate Slow Very slow
Rate (mm/hr) >130 60-130 20-60 5-20 1-5
