MAGNESIUM STATUS OF THE SAVANNAH SOILS OF NIGERIA IN RELATION TO TOBACCO PRODUCTION
MAGNESIUM STATUS OF THE SAVANNAH SOILS OF NIGERIA IN RELATION TO TOBACCO PRODUCTION
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Date
1983-11
Authors
ELKASED, FARAG AHMED
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Abstract
Under a system of continuous cultivation in
northern Nigeria, a number of nutrients which were
hitherto considered adequately supplied by the soil are
becoming deficient, one such nutrient is Mg. There is
need to establish the various availability indices for
the nutrient under the semi-arid savannah conditions.
Six extraction procedures of analysis involving
two extractants (Ammonium acetate and Calcium chloride)
were used. The amounts of magnesium extracted by these
various methods differed significantly. Increasing
extraction time or the concentration of the extractant
tended to increase the Mg extracted. Plant uptake of
Mg correlated well with Mg extracted by all methods,
though, repeated and single extraction with 1 N NH4 OAc
appeared the most suitable.
Magnesium status of the surface soils of different
locations as assessed by the single extraction with
ammonium acetate procedure showed that the savannah
soils of northern Nigeria are generally low in Mg. The
mean values of Mg of the Sudan savannah, Guinea savannah,
and southern savannah zones were 0.54; 0.96 and 0,56 meq/
lOOg respectively. Regression analysis showed linear
relationships between exchangeable Mg and soil CEC, clay
Ca, organic matter and silt in descending order indicating
their relative importance in predicting Mg levels of these
soils.
Profile sampling in some tobacco growing areas
revealed that Mg content increased with depth, the top
soil containing the lowest amount. This distribution
pattern is attributed to leaching and clay illuviation.
High correlation existing between Mg content and each
of organic matter and clay at all depths stresses their
importance and the need to maintain the organic matter
content of these soils. Magnesium content of field
tobacco was considered low averaging about 0.26% and
there was no correlation between plant and soil Mg which
suggests that the latter may not be the only factor
controlling Mg uptake under field condition. However,
in the green house, Mg uptake was largely dependent upon
soil Mg status.
Application of Mg to generally acid scils, sandy to
silty loam, low in organic matter, CEC, and nutrient
status, particularly Mg and K improved the growth of
tobacco plants and increased the leaf yield most
especially at 24 kg Mg/ha, Magnesium content of leaves
was increased but that of calcium, potassium, nicotine,
total nitrogen and reducing sugar were not significantly
affected, though there was a tendency tof decrease of
reducing sugar with Mg application. There was no
interaction between Mg and K on the chemical components
of tobacco leaves and yield within the range of
application of both elements.
The generally low level of plant - available Mg in
the soils studied coupled with the significant response
obtained to Mg application suggest that Mg deficiency
may attain wide scale importance in the semi-arid
savannah zone of Nigeria in no distant future
Description
A Dissertation submitted to the Faculty of Agriculture
in partial fulfillment of the requirements for
the degree of Doctor of Philosophy of Ahmadu
Bello University.
NOVEMBER, 1983
Keywords
MAGNESIUM,, STATUS,, SAVANNAH,, SOILS,, NIGERIA, RELATION,, TOBACCO,, PRODUCTION.