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FIXED AMMONIUM IN NIGERIAN SOILS I. SELECTION OF A METHOD AND AMOUNTS OF NATIVE FIXED AMMONIUM
Author(s) -
OPUWARIBO E.,
ODU C. T. I.
Publication year - 1974
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1974.tb01122.x
Subject(s) - ammonium , soil water , nitrogen , chemistry , environmental chemistry , zoology , mathematics , soil science , environmental science , biology , organic chemistry
Summary Three of the common methods for the determination of native fixed ammonium in soils‐the Rodrigues modified, the Bremner KOH method, and the Silva Bremner method‐were evaluated and the Silva‐Bremner method was chosen. Native fixed ammonium in 212 profile samples representing different soil types and sampling localities in Nigeria was found to range from 4 to 98 ppm. Fixed ammonium accounted for 1‐7 per cent of total nitrogen in surface soils and 3‐48 per cent in the sub‐soils. More than half of the values fell within the ranges 2‐4 and 8‐20 per cent respectively. The results do not agree with the high values reported earlier for four Nigerian soil profiles. Fixed ammonium, both in absolute amounts and as a percentage of total nitrogen, increased with depth in most profiles though maximum amounts were not necessarily attained in the lowest horizons. Fixed ammonium values were lower in soils derived from sandy parent material than in those derived fromigneous or metamorphic rock and were generally less in the more humid southern parts of the country than in the drier north. Fixed ammonium, especially in subsoils, contributes to the nitrogen economy in these soils.