C - Lublin
C - Lublin
C - Lublin
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metal concentrations were determined using the atomic absorption method. To<br />
obtain the HA and FA fractions, the 0.1 N NaOH extracts were acidified to pH 1.5<br />
with 1 N H 2 SO 4 . After the separation of precipitated HA from acid FA solution, the<br />
P content in two fractions was determined by the Murphy-Riley method. The<br />
contents of C, Fe, and Al were determined as noted above.<br />
Difference electronic spectra of the alkaline extracts, HA and FA were<br />
obtained using the solvent (0.1 N NaOH for soil extracts and HA, a mixture of 0.1<br />
N NaOH and 1 N H 2 SO 4 for FA) as a reference.<br />
The HA obtained from initial soil was used to prepare Fe-HA complex. The<br />
treatment of HA with FeCl 3 provided C:Fe ratio of 1:6. The Fe-HA complex<br />
prepared was treated for five weeks with KH 2 PO 4 solution added to have a C:P<br />
ratio of 1:17. The pH value for systems was 4.1. Control complex and its P-<br />
modified organic product were used for the IR examination (KBr – technique). IR<br />
spectra of HA and FA from initial soil were also obtained.<br />
RESULTS AND DISCUSSION<br />
Table 1 shows that extractability of C and M by 0.1 N NaOH tended to<br />
increase with increase in incubation period of P-enriched soil. Under these<br />
conditions, the difference in distribution of alkali-soluble C and M between the HA<br />
and FA fractions became more and more obvious. The amount of C associated with<br />
HA was greater, the greater was the incubation period of P-enriched soil. On the<br />
contrary, the amount of M associated with HA decreased sharply after one-year<br />
incubation of soil enriched in P.<br />
Table 1. The contents of C org , metals (Fe+Al), and P, mg/100 g soil<br />
Soil treatment<br />
1 year incubation<br />
without P<br />
with added P<br />
0.1 N NaOH<br />
extract<br />
HA<br />
FA<br />
C org M C org M P C org M P<br />
628<br />
570<br />
170<br />
210<br />
369<br />
365<br />
87<br />
114<br />
10<br />
24<br />
259<br />
205<br />
83<br />
96<br />
10<br />
29<br />
3 years incubation<br />
without P<br />
with added P<br />
657<br />
745<br />
190<br />
250<br />
403<br />
552<br />
107<br />
73<br />
4<br />
3<br />
254<br />
193<br />
83<br />
177<br />
11<br />
58<br />
99