Increasing Rice Production Using Different Lime Sources on an Acid Sulphate Soil in Merbok, Malaysia

Acidity is released in high amounts when pyrite-bearing sediments in the coastal plains ofMalaysia are drained for development, either agriculture or otherwise. The soils formedfrom these materials are called acid sulphate soils, which are characterized by low pHand high exchangeable Al that adversely affect plant growth. A study was conducted withthe 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 withground 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 commonvariety grown in Malaysia. Prior to treatments, the pH of water sample in the rice field was3.7, while Al concentration was 878 μM. Thus, rice plants grown under these conditionswould suffer from H+ and Al3+ stress without amelioration, thus retard and/or minimize ricegrowth and yield. In the first season (1st season) rice plants were affected by drought duringthe vegetative period, while in the subsequent season (2nd season), they were infested withrice blast fungus (Magnaporthe grisea). In spite of that, however, the rice yield was 3.5 tha^-1 based on the application of 4 t GML ha^-1, which was almost equivalent to the averagenational yield of 3.8 t ha^-1. As a result, it was noted that the ameliorative effects of limeapplication in the 1st season had continued to the 2nd season. Liming at 4 t GML ha^-1 incurshigh cost to the farmers. However, the yield obtained is worth the effort and cost.