The strongly acid salty paddy soils derived from noncalcareous allitic sediment are widely distributed in the estuary of Chu-Kiang of Kwangtung province. Before recent sediments have deposited, the whole areas were densely covered by mangrove populations. A buried layer of decomposed products from residual plants is often underlaid at varied depth of present soil profiles. This layer contains large quantities of sulphide compounds. Oxidation of sulphides under acid conditions during dry period results the formation of sulfuric acid, which reacts with the kaolinitic clay to form aluminium sulfates. Periodical floodings of sea water add salinity of the soil and upon hydrolysis of the aluminium sulphate give a strongly acid reaction. The toxicity of the soil is mitigated with the increasing thickness of overlaid sediments. However, large areas of strongly acid salty soil with underlaid organic matter layer less than 25 cm below the sulface appear very harmful to rice growth. Reclamation of the soil can be accomplished by: a) irrigation of river water, b) keep the soil in a permanent moistened condition, c) liming, and d) addition of surface soil.