Physio-Chemical Properties, Growth Activities in Ground Nut (Arachis Hypogaea) by Individual and Mixed Soils (Red Soil, Black Soil, and Alluvial Soil) from Delta Zone of Tamilnadu, India

Abstract

Background: Soil physico-chemical characteristics strongly influence plant growth and agricultural productivity, particularly in nutrient-demanding crops such as groundnut (Arachis hypogaea). Red, black, and alluvial soils of the Tamil Nadu delta region exhibit distinct fertility profiles, and their mixing may modify nutrient availability and crop performance. Aim: This study systematically evaluated the effects of individual and mixed soil systems on soil properties and groundnut growth responses. Methods: A controlled experimental study was conducted using red soil, black soil, and alluvial soil collected from Pudukottai, Coimbatore, and Thanjavur districts of Tamil Nadu, India. Soil samples were analyzed individually and in equal combinations (1:1 and 1:1:1). Physico-chemical parameters including pH, electrical conductivity, texture, water-holding capacity, organic carbon, and macronutrients (N, P, K) were assessed using standard laboratory methods (Walkley–Black, Kjeldahl, Olsen, and flame photometry). Groundnut seeds were grown in each soil type under controlled conditions for 30 days. Growth performance (germination, plant height, leaf and branch number) and biochemical parameters (chlorophyll, moisture, and ash content) were recorded and compared across treatments. Results: Mixed soil treatments showed improved physico-chemical properties compared to individual soils, with higher organic carbon (0.25–0.64%), nitrogen (50–72.4 kg/ha), phosphorus (7–10 kg/ha), and potassium (85–500 kg/ha). Soil pH remained moderately alkaline (7.9–8.4) across all treatments. Water-holding capacity and nutrient retention were notably higher in mixed soils, particularly in black–alluvial and tri-soil combinations. Enhanced plant growth was observed in mixed soils, with maximum plant height reaching 25 cm and improved leaf and branch formation. The red–black–alluvial (1:1:1) combination recorded the highest chlorophyll content (13.6 µg/100 mg fresh leaf), along with improved moisture and ash content. Germination and plumule development were also faster and more uniform in mixed soil systems. Conclusion: The blending of red, black, and alluvial soils significantly enhances soil fertility and improves groundnut growth performance. Mixed soil systems optimize nutrient availability, moisture retention, and overall soil quality, making them more suitable for sustainable agricultural and horticultural applications. The study highlights soil blending as an effective strategy for improving crop productivity in deltaic regions of Tamil Nadu.