An Evaluation of Indices of Available Nitrogen in Soils of Madras State

Abstract

Soil testing for available N is not comparatively as simple as in the case of soil test for availabe P or K. Many indices of N availability have been followed by different workers. These indices mainly fall under three major categories, namely, measurement of the potential source of mineralisable N, measurement of N mineralised by some chemical treatment and the measurement of N mineralised during incubation. Attempts have been made in the past to correlate the N values obtained by one or the other method with crop yield and N uptake. The alkaline permanganate oxidisable N is being used as an index of available N in Tamil Nadu. The present investi- gation was conducted to evaluate the merits of this soil N availability index and also of the four other indices, namely, total soil N, organic carbon content of the soil, nitrate N and ammoniacal N. The relationships between the alkaline permanganate oxidisable N and the other four indices were also studied in order to find out whether the former index could be substituted by the latter indices.

DOI

https://doi.org/10.29321/MAJ.10.A03464

Pages

69 - 72

Creative Commons

Copyright

© The Author(s), 2025. Published by Madras Agricultural Students' Union in Madras Agricultural Journal (MAJ). This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited by the user.

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