NITROGEN-SUPPLYING POWER OF SOILS FROM LAKE CHAD BASIN
NITROGEN-SUPPLYING POWER OF SOILS FROM LAKE CHAD BASIN
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Date
1980
Authors
Omeje, Michael. U.
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Abstract
Laboratory and greenhousee studies were carried
out with soils sampled from Lake Chad Basin in Sudan
and Sahel savanna zones of Nigeria to assess their
nitrogen-supplying potentials. Soil-nitrogen availability
indices that were evaluated included two
Chemical methods - acidified KMn04 and alkaline KMnC04
solution extractions and microbiological procedure -
(incubation).
For the upland soils the average N uptake
(N-supplying power) from the first, second and third
crops of wheat were 27, 16 and 12 mg/pot respectively.
The respective values for "fadama" soils were 28, 15
and 13 mg/pot.
The NH4-N extractable by acid KMnC04 method ranged
from 47 to 760 ppm. The minimum and maximum values of
NH4-N extractable by the alkaline KMn04 extraction were
16 and 205 ppm respectively. Total N mineralized by
incubation procedure ranged from 46 to 301 ppm. The
soils ability to supply N was not large and N uptake
tended to decrease with subsequent cropping.
The two chemical soil-N availability tests apart
from being more rapid appeared to be more superior as
indices of soil-N availability than the incubation
procedure whose correlation coefficients with N uptake
and dry matter were not only very poor but erratic.
ii Of the two chemical methods, the acid KMn04
extraction seemed much more promising as indicator
of soil-N availability than the alkaline KMnO4 procedure.
While the alkaline KMnO4 method tended to
have positive and general correlation with yield in
all the various groupings of the 24 soils, the acid
KMnO4 showed significant and positive correlation with
N uptake from first and third crops of wheat for soils
derived from alluvial sand deposits (r = 0.81* and
0.85* respectively) and also with N uptake from first
crop and total dry matter for "fadama" soils (r = 0.60*
and 0.52*, respectively).
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NITROGEN-SUPPLYING POWER OF SOILS FROM LAKE CHAD BASIN, NITROGEN-SUPPLYING POWER OF SOILS FROM LAKE CHAD BASIN