Increasing Rice Production Using Different Lime Sources on an
Acid Sulphate Soil in Merbok, Malaysia
ABSTRACT
Acidity is released in high amounts when pyrite-bearing sediments in the coastal plains of
Malaysia are drained for development, either agriculture or otherwise. The soils formed
from these materials are called acid sulphate soils, which are characterized by low pH
and high exchangeable Al that adversely affect plant growth. A study was conducted with
the objective of increasing rice yields on these soils under rain-fed condition in Merbok,
Kedah, Malaysia, using various lime sources. The acid sulphate soil was treated with
ground magnesium limestone (GML), hydrated lime and liquid lime at specified rates.
Paddy variety MR 219 was tested in a field experiment as this variety is the most common
variety grown in Malaysia. Prior to treatments, the pH of water sample in the rice field was
3.7, while Al concentration was 878 μM. Thus, rice plants grown under these conditions
would suffer from H
+
and Al
3+
stress without amelioration, thus retard and/or minimize rice
growth and yield. In the first season (1
st
season) rice plants were affected by drought during
the vegetative period, while in the subsequent season (2
nd
season), they were infested with
rice blast fungus (
Magnaporthe grisea
). In spite of that, however, the rice yield was 3.5 t
ha
-1
based on the application of 4 t GML ha
-1
, which was almost equivalent to the average
national yield of 3.8 t ha
-1
. As a result, it was noted that the ameliorative effects of lime
application in the 1
st
season had continued to the 2
nd
season. Liming at 4 t GML ha
-1
incurs
high cost to the farmers. However, the yield obtained is worth the effort and cost.