Simple modification of the Walkley-Black method for simultaneous determination of organic carbon and potentially mineralizable nitrogen in tropical rice soils

Sahrawat, K L (1982) Simple modification of the Walkley-Black method for simultaneous determination of organic carbon and potentially mineralizable nitrogen in tropical rice soils. Plant and Soil, 69 (1). pp. 73-77. ISSN 0032-079X

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Abstract

A modified version of the Walkley — Black method of organic C determination is described, which allows simultaneous determination of organic C and potentially mineralizable N in soils. As usual the organic matter of the soil is oxidized by acid dichromate reagent by heat of dilution. The excess of chromate left after C oxidation is titrated with standard ferrous sulfate solution instead of ferrous ammonium sulfate to avoid contamination due to NH4 +. The NH4 + released due to oxidative action of acid dichromate is determined by distilling a suitable aliquot from the known volume with 50% of NaOH solution. The ammonium released by this method with 15 surface soils showed highly positive correlations with organic C (r=0.969**), total N (r=0.976**) and the NH4 + produced under waterlogged conditions (r=0.985**). The modification is very simple and is easily adaptable for estimation of potentially mineralizable N in soils alongwith organic C determination.

Item Type: Article
Divisions: UNSPECIFIED
CRP: UNSPECIFIED
Uncontrolled Keywords: Acid dichromate - Anaerobic incubation - Release of ammonium - Total N
Subjects: Others > Soil Science
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 16 Nov 2011 13:18
Last Modified: 23 Jan 2012 08:17
URI: http://oar.icrisat.org/id/eprint/3994
Official URL: http://dx.doi.org/10.1007/BF02185705
Projects: UNSPECIFIED
Funders: International Rice Research Institute
Acknowledgement: I gratefully thank the International Rice Research Institute, Los Banos, Philippines for financial support and Dr. F. N. Ponnamperuma, Principal Soil Chemist for his interest in the work.
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