Journal of Pharmacognosy and Phytochemistry 2017; 6(6): 917-922 E-ISSN: 2278-4136 P-ISSN: 2349-8234 Surface and sub-surface studies on physico-chemical JPP 2017; 6(6): 917-922 Received: 28-09-2017 properties of selected red soil type of Haveri district, Accepted: 30-10-2017 Karnataka Harsha BR Department of Soil Science and Agricultural Chemistry, College Harsha BR and Jagadeesh BR of Agriculture, Dharwad, UAS, Dharwad, Karnataka, India Abstract Jagadeesh BR The twenty representative red soil types spreading over seven taluks of Haveri district of Karnataka were Associate Professor, Department studied for selected physico-chemical properties during 2016-17 at UAS, Dharwad. In general, soil pH of Soil Science and Agricultural increased with depth in almost all samples except in Kengapur-1 and Medleri-4. This might be due to Chemistry, College of development of these soils by acidic parent materials which lack in basic cations. The electrical Agriculture, Hanumanamatti, conductivity values were well within the range in both the soils at both the depths indicating that no UAS, Dharwad, Karnataka, harmful effects of salts. The red soils recorded low to high oxidation rates in surface and sub-surface India samples it may be due to low addition of organic matter into soils and continuous cropping. The texture of red soils varied from sandy clay loam to clay loam in both the depths. The surface layer clay content was lower compared to sub-surface clay content. It may be because of chemical weathering resulted in formation of finer particles. The increase in CEC with depth was observed because of increase in clay content with depth. The Exchangeable Potassium Percentage (EPP) recorded higher values in surface layer compared to sub-surface layer of red soils. The high EPP values in surface may be due to high exchange sites offered for potassium. In surface soils, the Potassium Adsorption Ratio (PAR) values were more compared to sub-surface depth in red soils selected for the study. The surface samples of red soils recorded lower values due to low adsorptive sites and coarse texture, with increase in depth the texture changes from coarser to finer which might have offered high adsorptive sites. The available potassium in red soils was medium to high in status. The variation in K status might be due to cultural practices, application of fertilizers, organic manures and other inputs. Keywords: Surface and sub surface physico-chemical properties- pH, EC, OC, CEC, Exchangeable potassium percentage, Potassium adsorption ratio and Available potassium Introduction Soil being a heterogeneous body varies itself from its surface to sub-surface levels. The physico-chemical properties of soils play an important role in influencing the behaviour of plant growth. Soil texture, for example, determines not only the nutrient supplying ability of soil solids but also the supply of water and air to plant life. Soil texture especially can have a profound effect on many other properties. The character and make-up of the soil play an important part in the behaviour of soils and what they can be used for. Two of the most important properties of soils are their texture and structure. The main components of soil texture are: sand, silt and clay particles and organic matter. Soil texture, for example, determines not only the nutrient supplying ability of soil solids but also the supply of water and air to plant life. Soil texture especially can have a profound effect on many other properties. Farmers rely on pH testing to maintain quality soil that will produce the healthiest crops. The pH is master variable in soil, knowledge regarding pH helps in management of plant nutrients and their dynamics. The electrical conductivity of soil shows among other properties depending on temperature very interesting effects, which can be used technically. Soil organic carbon (SOC) is one of the major pools of carbon. The SOC pool is about double the size of the atmospheric carbon pool and about 3 times the size of the biotic carbon pool. Cation Exchange Capacity (CEC) is a measure of the ability of soil to hold positively charged ions. It is very important soil property influencing soil structure stability, nutrient availability, soil pH and reaction to fertilisers and other ameliorants. The surface of an individual clay particle or organic colloid is negatively (-) charged. As a consequence their surfaces attract and Correspondence adsorb positively charged ions called cations. When water is added to soil, cations can move Harsha BR into solution, however, they are still attracted to the clay particle or organic colloid surface and Department of Soil Science and as a result swarm around them. As rocks break down into the particles of sand, silt and clay Agricultural Chemistry, College of Agriculture, Dharwad, UAS, that make up soil, potassium and other elements are released and may become available to Dharwad, Karnataka, India plants. It is important to assess the quantity of potassium in the soil solution and the readily ~ 917 ~ Journal of Pharmacognosy and Phytochemistry available pool to ascertain whether or not to apply potassium surface samples and that of sub-surface was highest in fertilizer. This study helps planners in general and particularly Byadgi-1 soils (6.18 g kg-1) and lowest in Kengapur-2 soils for those planners depending on surface and sub-surface (3.12 g kg-1). The pH of the red soils were slightly acidic to characteristics of a soil. neutral which ranged from 6.38 to 7.50 and 6.37 to 7.52 in surface and sub-surface samples, respectively. In general, soil Material and Methods pH increased with depth in almost all samples except in The surface (0-20 cm) and sub-surface (20-50 cm) samples Kengapur-1 and Medleri-4. This might be due to development were collected, based on predominance of soil type and of these soils by acidic parent materials such as granite gneiss dominance of cropped area under maize. Haveri district and laterites which lack in basic cations. The results are in consists of seven taluks and covers a total geographical area corroboration with those of Bangroo et al. (2014) [2]. The of 4848 sq. km (Anon., 2015) [1]. The net cultivated area of increased pH with depth may be attributed to leaching of salts the district is 17,488 ha (Anon., 2015) [1]. The annual rainfall and its accumulation in lower layers (Gangopadhyay et al., of the region is 792.70 mm (Anon., 2015) [1]. The study 2005) [6]. The electrical conductivity values were well within location lies between the coordinates of 14˚ N to 75˚ E. The the range in both the soils at both the depths indicating that no soil samples collected were air dried in shade, gently ground harmful effects of salts, which depict that soils are well using wooden pestle and mortar and passed through 2 mm drained. The sub-surface soils recorded high EC which may sieve. The sieved samples were preserved in polythene plastic be because of leaching of salts and its accumulation. These covers for further analysis. Soil reaction was determined in research findings are in line with the findings of Hebsur 1:2.5 soil water suspension after stirring for 30 minutes using (1997) [8] and Jagmohan and Grewal (2014) [11]. The red soils a pH meter (Jackson, 1973) [9]. It was determined in 1:2.5 soil: recorded low to high oxidation rates in red sandy soils and water suspension after obtaining supernatant as described by organic carbon content in surface and sub-surface and it may Jackson (1973) [9] using conductivity meter. Organic carbon be due to low addition of organic matter into soils and was determined by Walkley and Black’s wet oxidation continuous cropping. The findings are on par with the method as described by Piper (1996) [14]. The per cent findings of Ghosh and Singh (1997) [7] and Kundu et al. distribution of particles of different size viz., sand, silt and (2014) [12]. The presence of high organic carbon indicates that clay was determined by mechanical analysis using Bouyoucos there is regular addition of organic substances to these soils. Hydrometer method (Jackson, 1973) [9]. Soils (50 g) were Decreasing trends in organic carbon content with lower soil shaken with 100 ml of 5 per cent solution of sodium hexa depth/horizons in all samples might be due to the fact that less meta phosphate. Later, per cent silt and clay was estimated by crop residues were incorporated in lower depth than surface hydrometer and per cent sand was calculated by subtracting layer. Similar results were obtained by Deepika (2016) [5]. The silt and clay from 100. The exchangeable calcium and experimental data on particle size distribution of red soils magnesium were determined in the neutral normal ammonium revealed that the sand content ranged from 36.32 to 60.96 per acetate the aliquot of the extract was titrated against standard cent in surface soils. In sub-surface, sand content ranged from versenate solution and sodium and potassium were 30.31 to 56.05 per cent. The silt content of surface and sub- determined by flame photometry (Jackson, 1973) [9]. surface soils varied from 15.76 to 25.88 per cent and 20.10 to Available potassium was determined by extracting soil with 28.96 per cent, respectively. The clay content of surface and neutral normal ammonium acetate and the contents of K in sub-surface soils varied from 21.33 to 36.73 per cent and solution and was estimated by flame photometery (Jackson, 24.45 to 37.67 per cent, respectively. The mean values of 1973) [9]. The exchangeable potassium percentage in soils was sand, silt and clay were 54.02, 18.91 and 25.24 per cent, determined with following formula (U.S.D.A, 1954) [16].