CHEMICAL CHARACTERISTICS OF ACID SULFATE SOILS AS AFFECTED BY ADDITION
OF CALCIUM SILICATE IN-COMBINATION WITH AND/OR WITHOUT GROUND MAGNESIUM
This study was conducted to evaluate the integral effect of ground
magnesium limestone (GML) and calcium silicate on acid sulfate soils in
Malaysia and to determine the optimal combination of GML and calcium
silicate, with consideration on the cost incurred by the farmers and the
positive soil chemical characteristics improvement on acid sulfate soil.
The acid sulfate soils were incubated under the submerged condition for
120 days with GML (0, 2, 4, 6 t ha-1) in combination with calcium
silicate (0, 1, 2, 3 t ha-1). A total of 9 out of 16 combination rates
met the desired requirement of chemical soil characteristics. The
chemical soil characteristics are soil pH > 4, exchangeable
Al < 2 cmolc kg-1, exchangeable Ca > 2 cmolc
kg-1, exchangeable Mg > 1 cmolc kg-1 and Si content
> 43 mg kg-1. Furthermore, 2 out of 9 combination rates (i.
2 t ha-1 calcium silicate + 2 t ha-1 GML, and ii. 3 t ha-1 calcium
silicate + 2 t ha-1 GML) cost were below the cost of 4 t ha-1 GML value
of USD 668, which is a common rate used by the farmers in Malaysia.
Thus, possible recommendation are, i) 2 t ha-1 calcium silicate + 2 t
ha-1 GML cost USD 484 and, ii) 3 t ha-1 calcium silicate + 2 t ha-1 GML
cost USD 559. These combination rates met the desired requirement of
soil chemical characteristics and could reduce the liming cost of
rice-farmers in Malaysia under acid sulfate soil.