Field Study on Soil Organic Matter Content in Inundation Areas of Langol Catchment by “Loss-on-Ignition” Method

Abstract

Organic matter content is an essential and distinguishing feature of soils that is commonly measured as a sink and source of carbon in the soil. Soil organic matter (SOM) is described as the total of vegetation and animal remains at different phases of decomposition, cells, and tissues of soil living systems, and substances that have decomposed well. It is a good measure of the fertility of the soil and is among the most vital agricultural soil components. It has a significant impact on soil physiochemical and biological features such as soil structure, water holding capacity, rate of water infiltration, and soil erodibility. The aim of this study is to find out the variation in soil organic content and its corresponding soil moisture content (SMC) for various land use and land cover types (agriculture, barren land, forest, built-up, and marshy land) in a frequently inundated region (Langol catchment situated in the North East region of India). The loss-on-ignition approach (LOI), which is a simple yet comprehensive method, is used for determining organic matter content in soil (measurement was recorded at a soil depth of 0–15 cm and 15–30 cm at each location of a total of ten sites (20 samples) from October 2021 to February 2022). It was observed that the organic matter content of the soil varies from 2.2% (moderately fertile) to 18% (highly fertile) depending on the type of land use and land cover. A higher value of SOM content (mean value) was observed in agriculture (15%) and forest land regions (17%), and its value reduced as the soil depth is increased. The higher SOM content in the top soil layer is due to the presence of appreciable plant and animal residues accumulated on the soil surface. Furthermore, there was no prominent co-relationship found between moisture content (17–57%) and its organic matter presence in the soil. Even though the study area lies in the low-lying region due to the presence of a higher built-up area (45%) and only 7% of agricultural land, the study location is not much used in agricultural activity at present. However, the soil in this study region is fertile and suitable for agricultural activity, but due to an increase in settlement (urbanisation) areas, in the future, organic matter presence may be drastically reduced, which affects the overall environment ecosystem in the region.