Udayakumar J., Muhammed Ajmal, Akhil R., Muhammed Farooq Z. and Rahul R.
Abstract
This study focuses on the variations of Soil Organic Carbon (SOC) contents in soils of different land uses like forests, agricultural lands, water bodies, built up areas and industrial areas in Kollam district of Kerala. It is to find the probable environmental implications of the variation in the content of SOC in soils of different land use types of the study area. Soil samples each from the different land uses were collected in polythene bags and the SOC and nitrogen of the soil samples were analysed using CHNS analyser. The soils in the study area are mainly sandy in type. The percentage of gravel is the lowest in the industrial area and the highest in agricultural areas. The sand percentage is minimum for agricultural land and is maximum for industrial areas. The content of fines in the soils of built up areas in the study area is minimum and that in the agricultural land is maximum. The standard deviation of fines is maximum for agricultural lands and minimum for industrial areas.The percentage of fines shows a decrease in trend from forest to built- up /industrial areas. Nitrogen content also follows similar variation. There is no correlation between gravel content and SOC. Sand content in the soil is negatively correlated with the SOC. The percentage of fines shows a positive correlation with SOC. Standard deviation of SOC is similar to standard deviation of percentage of fines. The soils of industrial and built up areas of Kollam district mainly belong to the coastal part of Kollam district. Undisturbed subsurface soils from these areas contain lot of carbonaceous clay and peat. But due to intense land use activities associated with urbanisation, the SOC in the surface layers of the soil might have been removed by soil respiration. This might have locally added CO2 from the soil to the atmosphere. Its local implications on a global phenomenon like climate change is important. It is also interesting to note that SOC closely follows changes in the content of fines in the soil. The land use activities in industrial and built up areas do not permit the formation of fine SOC associated fraction in these soils.