الفهرس 
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Abstract
The study concerned assessment of the response of sudan
grass (Sorghum Sudanese) to addition of each of Mn (0, 5 and 10 J.Lg
g-1) or Zn (0, 2 and 5 ).1Qg-1)or.Cu (0, 1 and 2 J..LQg-1) to a clay soil (51)
and a loamy sand one (52) in presence of various rates of P (0, 15, 30,
45 and 60 J.LQg-1). Contents of NH4HC03~DTPA~extractable Mn, Zn
and Cu in soils were respectively 7.9,12.5 and 2.1 in 51; and 0.9,3.6
and 0.8 J..LQs’’ in 52. Factorial pot experiments were conducted
involving P and each of the concerned micronutrients. Response of
adding Mn, Zn, or Cu was assessed with regard to plant growth and
uptake of nutrients by roots and shoots (in the loamy sand soil), or
shoots only in the clay soil (due to difficulties in removing roots).
Manganese:
Soils needed Mn particularly in absence of P. In presence of P
(particularly at high rates), Mn caused a slight positive response for
plant growth and (in most cases) a depression in absorbance of Mn by
plants. In absence of PI a positive response was pronounced for plant
growth and Mn absorbance. Precipitation of Mn in form of phosphates
in soil and/or a retardation in Mn translocation from roots to shoots may
have occurred due to presence of high P; since roots of Mn-fertilized
plants retained more than half of plant Mn in presence of P, compared
with less than half in absence of P.
Zinc:
Soils needed Zn especialy the loamy sand soil. In presence of
P, Zn caused smaller response for plant growth and a general
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reduction in Zn absorbance by-plants. A probable suppression of Zn
absorbance due to P application may have been the reason; but a
retardation in Zn translocation from roots to shoots within the plant was
not clear: since roots contained less proportlon (39%-46%) of plant Zn
in presence of P than in its absence (46%-50%).
Copper:
The two soils responsed (positively) to Cu addition and this
reflects a need for Cu application in order to increase plant groWth.
Concerning Cu uptake, positive response to Cu was generally marked
although a slight depression of Cu uptake occurred under effect of P
applied at high rates in particular, indicating a ”dilution effect” or a
depression in Cu absorbance by high phosphate concentration in soil.