Vol.2, No.4, 487-490 (2011) doi:10.4236/as.2011.24062 Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/ Agricultural Sciences Phosphorus fixing capacity of the Oxic Rhodustalf— alfisol soil in the Chotanagpur plateau region of Eastern India Prabir Ghosal 1* , Trishit Chakraborty 2 , Pabitra Banik 3 1 Agricultural and Ecological Research Unit, Indian Statistical Institute, Kolkata, India; * Corresponding Author: pkghosal@isical.ac.in 2 Department of ASEPAN, Palli Siksha Bhavana, Sriniketan, Visva Bharati, Bolpur, India; 3 Agricultural and Ecological Research Unit, Indian Statistical Institute, Kolkata, India. Received 4 September 2011; revised 12 October 2011; accepted 30 October 2011. ABSTRACT The P-fixing capacity of a soil governs the P-nu- trition of crop plants. P-nutrition of the crop plant is more a soil problem and a higher dose of phosphatic fertilizer is necessary for soils having high P-fixing capacity. The phenomenon of P-fixation and the great variation in the P- fixing capacity of different soils has thus im- portant bearing on crop response to P-appli- cation. The eastern plateau region of India with acid lateritic soil is chronically deficient in av- ailable phosphorus resulting in very low pro- ductivity. An experiment was thus carried out to estimate the P-fixing capacity of soil collected from two depths, 0 - 20 cm and 20 - 50 cm, from the Agricultural experimental farm of Indian Statistical Institute, situated at Giridih, Jhark- hand, in the eastern India. The soil was acidic in reaction (pH-5.4) with presence of Fe (1.60%) and Al (17.2%). The P-fixing capacity of the soil was estimated to be 59.60% and 64.94% for the surface and the subsurface soil respectively showing lower P-fixing capacity of the surface soil as compared to the subsurface soil which may be due to presence of more organic matter in the surface soil as organic molecules re- leased on decomposition of organic matter com- plexes with Fe and Al in the soil thereby block- ing the P-fixing sites in the soil. Keywords: P-Fixing Capacity; P-Nutrition; P-Fixation 1. INTRODUCTION Phosphorus (P) is an essential element for plant growth and productivity, and lack of available P in soils can se- verely affect crop yields [1]. Plants extract P from the soil solution in the form of orthophosphate ion ( 2 4 H PO  or 4 HPO  ) and there is strong competition between plants and soil minerals for these forms of P, particularly in the highly weathered soils of the tropics, most of which contain large amounts of iron oxides, aluminum oxides, or amorphous alumino-silicate clays. These soil minerals “fix” P firmly through a process known as sorption, making the P virtually unavailable for plant uptake [2]. The P-fixing capacity of a soil is influenced by a number of factors, such as pH, CaCO 3 , sesquioxides, moisture and clay contents [3]. When phosphatic fertil- izers are added to a soil, a series of chemical reactions take place between the soil constituents and soluble phosphorus, rendering the added phosphorus relatively less available. The soil factors contributed to 80 to 83 per cent of the variations in the amounts of P fixed at various levels of added P and also of the maximum P fixation capacity [4]. Thus, it is now well understood that P-nutrition of the crop plants is more a soil problem and a higher dose of phosphatic fertilizers are thus nec- essary for soils having high P-fixing capacity. It has been reported that about 10% to 30% of added phosphorus, is utilized by the crop and the rest is accumulated in the soil in one form or another thereby enriching the reserve phosphorus pool of the soil. An increase in the Relative Agronomic Efficiency of less water-soluble P sources on high soil P adsorption capacity has also been reported [5]. Thus, the phenomenon of P-fixation and the great varia- tion in P-fixing capacity of different soils has important bearing on crop response to phosphorus application. The eastern plateau region of India is chronically low in productivity of food grains [6]. One of the reasons for this is attributed to very low phosphate availability of the soil (20 - 25 kg P 2 O 5 /ha) due to its acidic reaction and presence of large amount of hydroxides of iron and alu-