Impact of Diverse Agricultural Land Uses on Soil Organic Matter Fractions: A Comprehensive Evaluation
B. Bincy *
Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, India.
R. Gladis
Department of Soil Science and Agricultural Chemistry, Agricultural Research Station, Thiruvalla, India.
B. Rani
Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, India.
B. Aparna
Department of Soil Science and Agricultural Chemistry, College of Agriculture, Ambalavayal, India.
S. Sandeep
Department of Soil Science and Agricultural Chemistry, Kerala Forest Research Institute, Peechi, India.
J.S. Bindhu
Department of Agronomy, Integrated Farming System Research Station, Karamana, India.
*Author to whom correspondence should be addressed.
Abstract
Organic matter is a crucial component of soil that influences various soil properties and functions, including nutrient cycling, soil structure, water holding capacity and microbial activity. Different agricultural land uses significantly influence the quantity and quality of soil organic matter (SOM) fractions. The primary constituent of SOM is humic substances, also known as humus. These are stable compounds originating from the decomposition of organic matter derived from plants, animals, and microorganisms. The soil humic fraction is categorized into humic acid (HA), fulvic acid (FA) and humin (HN) based on the solubility in acid and alkaline medium. The structural arrangement, chemical constitution and stability of the humic substances in soil are affected by various factors, including climate, parent material, altitude, vegetation and the management practices employed in the area. In this context the present study was proposed to assess the impact of various agricultural land use systems on humic acid, fulvic acid and humin fraction in soils of different agro-ecological units (AEUs) of southern Kerala. The study focused on specific AEUs in southern Kerala, including the southern coastal plain (AEU 1), Onattukara sandy plain (AEU 3), southern laterites (AEU 8), south central laterites (AEU 9) and southern and central foothills (AEU 12). Within each AEU, various agricultural land use categories such as, coconut, rice, rubber and uncultivated land were selected as specific focal points for this investigation. The HA, FA and HN content in soil exhibited varying ranges across different AEUs, ranging from 0.57 to 2.06, 0.73 to 2.33, and 0.62 to 1.59 per cent respectively. Among the various land uses, rubber exhibited significantly higher levels of HA (1.72%), FA (2.01%) and HN (1.44%) compared to coconut, rice and uncultivated land. Among the different organic matter fractions, FA (32.30-36.18 %) contributed more towards SOM than HA (29.40-32.51 %) and HN (26.43-29.25 %).
Keywords: Soil organic matter, humic acid, fulvic acid, humin, land uses, agro-ecological units