RECOVERY OF SORBED FERTILIZER PHOSPHORUS BY THREE
WATER EXTRACTION METHODS
Anas,
W.& Füleky, GY.and Tolner, L., University of Agricultural Sciences,
ABSTRACT
The replenishment
of P in the soil solution is of considerable importance from the standpoint of
plant nutrition, for the reason that the quantity of inorganic P in the
solution phase at any time, is usually insufficient to meet crop requirements
over the whole of the growing season.
Through this
study we are concerned in the phosphorus recovery from the soil solid phase
that have received different levels of P-additions and of acidification
applying three different water extraction methods.
A calcareous loamy soil of pHH20
=7.9 was incubated with 0, 80 and 320 mgP.kg-1 soil for one month.
Different four levels of acidification (pH 7.9; 7.3; 6.0 and 4.5) were adjusted
by adding calculated volumes of HCl and incubating the soil samples for further
one month, then equilibrated with different rates of phosphorus as 0; 80; 160
and 240 µgP.10cm
. The desorbed quantity of
phosphorus was determined applying EUF, HWP and multistep desorption methods.
Some part of the
added phosphorus can be recovered by all methods, depending on the dose and
time of P addition (previous or recent), on acidity of the soil and on the
method used. The desorbable phosphorus amounts are in average 19% of the sum of
P-loading at 0 mgP.kg
level, and 31 and 64% at 80 and 320 mgP.kg levels, respectively.
Key words: Aqueous system, phosphorous fertilization;
P desorption, soil reaction pH.