Nitrogen mineralization and maize yield from a three years fallow of prosopis chilensis
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Date
1997
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
The study was conducted to assess the effect of three-year
old fallow of Prosopis chilensis (Molina Stuntz) on general
soil properties, nitrogen mineralization and maize yield
an
Tanzania.
experiment
agroforestry
on-going
The
design
of
the
at
experiment
Gairo,
was
a
on
Morogoro,
completely
randomized block design with three treatments: Trees alone
(T) ,
Maize
(M)
alone
replicated four times.
and
Trees
plus
maize
(T+M)
each
Soil samples were collected at the
beginning and at the end of the experiment at 0-15 and 15-30
cm depth. Soil samples for N mineralization were collected at
three weeks
intervals
from maize sowing up to tasselling
stage.
The results from the soil analysis at the beginning of the
experiment
showed
that
K+
differed
significantly
between
treatments. The trees alone treatment had the highest level
(1.0 cmol ( + ) kg1) than other treatments which had the lowest
level
(0.7 cmol
(+) kg'1). Magnesium differed significantly
between treatments, with the maize alone treatment having the
highest level of Mg2+ (2.0 cmoles(+) kg'1)
and the treatment
with trees alone having the least (1.6 cmoles (+) kg'1). Total
P differed significantly between (P<0.05) treatments with theiii
trees-alone treatment having the highest total P (229.6 ppm)
and treatment with maize alone having lowest value (159 ppm) .
Total N, organic C, available P, inorganic P, organic P, Na+
and Ca2+ were not significantly affected by treatments. Total
N and available P decreased significantly (P<0.05) with soil
depth. In contrast, Mg2+ and Ca2+ were higher in the subsoil
than in the top soil. At the end of the experiment, none of
the
nutrient
analyzed
differed
significantly
between
treatments. Results from N mineralization under laboratory
conditions in
significant
all
sampling
difference
periods
between
did
treatments.
not
In
show
any
contrast,
changes in mineral N under field conditions showed that the
treatment with trees alone had the highest release of mineral
N and was dominated by nitrate. Maize yield did not differ
significantly between treatments.
It is concluded that a three-year fallow of P. chilensis was
not long enough for soil fertility improvement even though
there was a significant difference on total P and release of
mineral N.
Description
Dissertation
Keywords
Nitrogen mineralization, Soil properties, Prosopis chilensis (Molina Stuntz), Maize yield, Agroforestry