MAGNITUDES OF BASIC SLAG ON IRON DYNAMICS IN TWO ACID SULFATE SOILS DURING 30-MONTHS OF INCUBATION UNDER VARIOUS MOISTURE REGIM

Abstract

The magnitudes of basic slag (BS) at 0, 10, 20 and 30 t ha-1 on iron dynamics in
two acid sulfate soils (ASSs) under moisture at field capacity, saturated condition
and wetting-drying cycle were studied during 30 months of incubation (25-30
0C). The impacts of BS in Sarisabari ASS were almost similar as those obtained
in Purbapukuria ASS under various treatments, but the increments of pHs in
Sarisabari ASS were not as pronounced as those observed in Purbapukuria ASS. The
pH valueswere increased by about 1.0, 1.5 and 1.2 units in Sarisabari and 2.0, 1.7 and
1.5 in Purbapukuria ASSs, those received BS30 at field capacity, saturated condition
and wetting-drying cycle, respectively and followed by BS20 > BS10 treatments. The
contents of basic cations in the studiedASSswere low to medium, while acidic cations
were very high in relation to the amounts found in the ASSs elsewhere. Magnesium
contents were about 2 to 3 -folds than those of Ca but Fe contents were very high.
The application of basic slag in the ASSs was found to reduce the acidity problems
noticeably and decreased the Fe contents remarkably. Neutralization of acidity by
BS30 at saturation moisture level was determined to be the best for both the ASSs
followed by moisture at field capacity and wetting-drying cycle. The soil pH was
found to have strong positive relationship with time, while the Fe contents showed
strong negative relationship with the corresponding pHs of the ASSs. These indicate
that the amelioration of ASSs by the application of BS is a sustainable reclamation
and improvement measures regarding Fe toxicity of the soils.