SOME INTERACTIONS OF ZINC IN SOIL AND PLANT

Abstract

TI1e study concerns the interactions between the element Zn and each of P, Fe, Cd, calciwn carbonate and clay. Zn and Fe added in soluble sulphate fonn, Cd in soluble cWoride form. The main considerations relate to implications on: (i) nutrient availability, and (ii) plant growth (wheat). The soil of the study was a non-calcareous sand collected from a sandy desert land about 40 km east of Cairo along the Cairo I Ismailia road. Calciwn carbonate source was in the form of limestone material applied in particle size of the following diameters: (1) 1.25-2.00 mm "D(, (2) 0.60-1.25 mm "D2", (3) 0.25-0.60 mm "D3" and (4) less than 0.25 mm "D4". The clay used in the study was as follows: (a) clay soil material "soil of 57% clay" taken from a field of the farm of the Agricultural Research Center (ARC), Giza (used in one experiment); and (b) two clay minerals (montmorillonite and kaolinite) used in another experiment. The experimntal work involved 11 experiments (6 laboratory incu-bation experiments and 5 greenhouse pot ones). The 6 incubation experiments were as follows: (1) Zn-P interaction; (2) Zn-Fe interaction; (3) Zn-Cd interaction; (4) Zn­ CaC03 interaction; (5) Zn- clay- CaC03 interaction and (6) Zn­ clay type- clay content interaction. Rates used were as follows: Zn: 0, 5, 10 and 20 Jlg g-1 ; P: 0, 10, 20 and 30 Jlg g- 1 ; Fe: 0, 20, 40 and 60 Jlg g-1 ; Cd: 0, 1, 2 and 4 Jlg g- 1 ; CaC03: 0, 5, 10 and 20 %; rates of clay addition (to the sand soil) were 0, 5, 10 and 20 %. Expeiiments design was a factorial randomized complete