الفهرس 
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Abstract
Tbe aIm of tbis work was to study the p-Zn interaction in
soils and plant. Tbree pots factorial experiments using
Egyptian clover ( Barseem; Trifolium alexandrianum c.v.
Giza I) were carried out using non-calcareous clay loam
(alluvial, from Sharkeya) and a calcareous sandy clay loam
(from Borg EI-Arab). Also a sand soil from tbe Eastern near
Enshas was used p32 and zn65 were used as tracers. One cut
of plant was taken after 45 days growth.
Pot experiment 1:-
Pbospbrus-Zinc interaction: using 24 combinations of 4
P doses (0,5,10, and 20 mg P kg-I) and 3 Zn doses (0,2.5,
and 5.0 mg Zn kg-I) on two 80ils (non-calcareouS clay loam
and the calcareous sandy clay loam) i.e. 4 x 3, x 2.
Results were 8S followS :-
1- In the alluvial soil P caused an increase in plant growtb
(7-13% yield increase), p_uptake (13-55%) and Zn-uptake
(31.-50%). Adding P at all doses increased yield only where
no Zn was present in the 80il; in presence of Zn, P caused no
effeel, especially in presence of the bigb Zn dose wbich
depressed growth generally. In the calcareous soil, yield as
we11 a. Zn-uptake WSB increased by applying P only in the
presence of zn.
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1- Application Zn to the alluvial aoil increaled yield only
when applied at the 1.5 mg Zn kg-I, the higher rate
decreued it. In the caicareoul loil there wu no such
decrealO. Very little part of fertilizer Zn (1-6%) wU
Iblorbed by plant. from about one-fifth to three-quarterB
(18-74%) of Zn-uptake wu of a fertilizer origin. Increuing
Zn rate decreued the part of fertilizer getting into plant, but
increased the part of uptake originating from fertilizer.
Pot experiment 2 :-
Pholphorul-Zinc interaction IR land uaing 17
combination of 3 P-dOIOI (0, 5, and 10 mg P kg-I). 3 ZIldo
se I (0, 1.5. and 5.0 mg Zn kg-I) and 3 CaC03addi Ii 011 to
land (0, 2.5, and 5.0 % CaCO,) i.e. 3 )( , )( 3.
lleBults were as folloWS :-
1- Pholphorul caUled illcreaBe in plant growth (9- 13% yield
increue) with no illieraction with Zn. P in prelence of
CaC
0
3 caused such an increaBe 10 be Imaller. Presence of
CaC
0
3 in itlOlf decreued yield. Allo applyillg P increued
p-uptake due to illcrelled planl growth and increalOd p.
concentration in plant.
1- Zinc caused no effect on plant growth ullder all cOllditionl
of P and\or CaCO, presence or .bsence.
3- Phoaphorul caulOd an illcreued to p-uptake ollly where
fertilizer ZII wu preaent, lillce ill the absellce of added ZII.
there WaB response to p-addition. There WaBIe •• fertilizer P
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In plants given any Zn· fertilizer than in plant given no Znfertilizer,
particularly where CaC03 was present.
Laboratory experiment :-
Experiments on sorption of fertilizer P or Zn by so i]
involved alluvial and calcareous soils, as well as the land
Boil. Soils were treated by adding p32 and Zn65 at the same
rates used in the pot experiments 1and 2. Treated soils were
left 24, 48, and 72 hours to determine the adsorption of p32
and Zn65 on lolid phase of the soil by measuring p32 and
Zn65 in liquid phase of the soil water luspension (the water
extract of the HoiI).
Results were as follows :-
(A) Within 72 hours, between 92 to 100% of loluble applied
p and between 82 to 100% of applied Zn were retained by
the alluvial soil. Comparable figures for the calcareous soil
were 94 to 100% applied P, 82 to 100% of applied Zn.
(B) Fixed, precipitated and/or adsorbed P by land loil
ranged between 74 to 98% within 72 bours of addition,
comparable portions of fixed, precipitated andlor adsorbed
Zn were 65 to 100% within 72 bours of addition (particularly
where CaCO, was added). The addition of CaC03 to land
greatly enhanced adsorption of fertilizer P.