Abstract:
Phosphorus (P) is an essential element for plant and animal growth; although plant roots are
capable of absorbing P from the soil solution at low P concentrations, most soils cannot
supply sufficient amounts of P to the plant due to various factors. Knowledge of the effect of
the P remaining in the soil (residual effect) is of great importance for fertilization
recommendation. Phosphorous fixation to soil results in less P available to plants. Nano
technology addresses the development of solutions to the existing environmental problems.
For this purpose, Fe-Al-Zr ternary mixed oxide Nano composite adsorbent with 70, 25 and 5
percentage composition of Fe, Al, and Zr respectively was synthesized by co-precipitation
method. The as-synthesized adsorbent was characterized by X-ray diffraction (XRD), Fourier
transform-infrared (FT-IR), flame atomic absorption spectroscopy (FAAS) studies and
Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX). The study of
phosphate desorption was carried out on four soil samples collected from West Wollega Zone,
Oromia region namely, Kiltu Kara, Nedjo Boji, Dirmeji and Mana Sibu which were incubated
with 0, 50, 100 and 150 ppm phosphate. Selected physicochemical properties of soil were
determined. The simulation of phosphate desorption from soil to plant was predicted by
dialysis membrane tube filled with Iron-aluminum-Zirconium oxide (DMT-Fe-Al-Zr). The results suggest that the phosphorus treatment and desorption time had significant effect on the
amount of desorbed phosphorus from the soils. The phosphate desorbed was found to be
highest at Kiltu Kara soil with 150 mg/Kg treatment which has the value ranging (4.51-
32.62.mg/Kg) and lowest in the control (1.42-15.591 mg kg-1
) at all levels of extraction time
for all soil types. The releasing rate of phosphate from soil followed first order kinetics having
highest desorption rate found on day 1 for Kiltu Kara soil sample with the value of 4.63
mg/Kg day-1 and the lowest was observed on day 28th of Boji Dirmeji (B) with the value of
0.44 mg/Kg day-1
. Therefore, the DMT- Fe-Al-Zr method can serve as analytical tool to assess
the availability of residual P in soil, which is essential to estimate available P for plants.
